ORCID Profile
0000-0002-7823-7185
Current Organisation
University of Nottingham
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Publisher: Springer Science and Business Media LLC
Date: 07-08-2023
Publisher: Wiley
Date: 27-03-2006
Publisher: Wiley
Date: 08-2010
DOI: 10.1890/08-2019.1
Abstract: Foraging theory predicts that mobile predators should target high profitability areas with plentiful resources and minimize time spent moving between these areas. This has led to a focus in recent literature on the identification of "hotspots" important for migratory marine predators, i.e., regions where predators spend disproportionate amounts of time ostensibly due to high prey abundance and determination of the environmental features characteristic of such areas. We investigated factors predicting foraging success in southern bluefin tuna (SBT Thunnus maccoyii), by integrating telemetry-based feeding and movement data (n = 19 fish, length to caudal fork [LCF] = 99 +/- 3 cm) with environmental data over the scale of their annual oceanic migrations during 1998-2000. We used widely available statistical modeling techniques, generalized linear models, and generalized linear mixed models, formulated to represent feeding as a Markov process. The results showed increased feeding and predictability of feeding occurs in the coastal waters of southern Australia, providing some evidence that this area represents a fixed foraging "hotspot" for juvenile tuna during the austral summer. However, in oceanic waters southern bluefin tuna did not fit the common model of migration, but rather showed a pattern of relatively high foraging success throughout their migratory range, especially during periods of continuous travel. Interestingly, foraging "coldspots" (prolonged low-feeding periods) as well as "hotspots" were apparent across in idual tracks, predicted most strongly by warm ocean temperatures. These results provide a new perspective on the ecology of large-scale feeding migrations within the context of the heterogeneous ocean environment, where the continuous and opportunistic feeding of generalist predators may be more common, particularly in predatory large pelagic fishes, than is currently documented.
Publisher: Wiley
Date: 11-07-2003
Publisher: Oxford University Press (OUP)
Date: 08-2002
Publisher: Oxford University Press (OUP)
Date: 2004
DOI: 10.1016/J.ICESJMS.2004.07.012
Abstract: We examined the relationships between physical oceanography (sea surface temperature – SST, sea surface height anomaly – SSH, ocean colour – OC, bathymetry – BA, sea-ice concentration – SI, and their associated gradients) and the foraging distribution (time at sea) of female southern elephant seals using generalized linear and generalized additive models (GLM and GAM). Using data from 28 separate foraging trips (22 unique in iduals) over two years, we found that during the post-lactation trips (summer), the best GLM demonstrated a negative relationship between time at sea and SST and BA, but a positive relationship with SST gradient and SSH. During the post-moult (winter) trips, there was a negative relationship with OC gradient, SSH, and BA. The best post-lactation GAM identified a positive relationship with OC gradient, negative relationships with OC and SST gradient, and a non-linear relationship with SST. For the post-moult trip there was a negative relationship with OC, SST, BA and BA gradient, and a positive relationship with SST gradient. The relationship between the predicted time and observed time at sea was significant only for the post-lactation GAM, although predictability was low. That SST and its gradient predicted a small, but significant proportion of the variation in time at sea is indicative of the frontal zones within this area that are generally more biologically productive than surrounding regions. It appears that coarse-scale oceanographic configuration influences foraging behaviour in southern elephant seals only subtly. Nonetheless, some of the mechanisms influencing predator foraging are congruent with expectations of distribution of marine food resources at coarse spatial scales.
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.SCITOTENV.2019.02.184
Abstract: Plastic pollution is a modern tragedy of the commons, with hundreds of species affected by society's waste. Birds in particular mistake plastic for prey, and millions of wild birds carry small plastic loads in their stomach and are exposed to potential toxicological effects. It is currently unknown how severely the toxicological and endocrine disrupting chemicals in plastic affect avian development, reproduction and endocrine function. To address this question, we conducted multi-generational plastic feeding experiments to test the toxicological consequences of plastic ingestion at environmentally relevant loads in Japanese quail, Coturnix japonica, investigating parental and two filial generations. Contrary to expectations, we found no evidence of lasting toxicological effects on mortality, adult body weight, organ histology, hormone levels, fertility, hatch rates and eggshell strength in birds experimentally fed plastic. However, we found plastic ingestion causes higher frequencies of male reproductive cysts and minor delays in chick growth and sexual maturity, though without affecting ultimate survival or reproductive output. We report that although plastic ingestion causes detectable endocrine effects in our model species, our lack of finding mortality, morbidity and adverse reproductive outcomes may challenge the common hypothesis of severe toxicological harm and population-level effects when environmentally relevant loads of plastic are ingested.
Publisher: Wiley
Date: 09-10-2023
DOI: 10.1111/MMS.13078
Publisher: Frontiers Media SA
Date: 27-04-2021
DOI: 10.3389/FPUBH.2021.610245
Abstract: Regular physical activity has a range of benefits for children's health, academic achievement, and behavioral development, yet they face barriers to participation. The aim of the study was to systematically develop an intervention for improving Chinese children's physical activity participation, using the Behavior Change Wheel (BCW) and Theoretical Domains Framework (TDF). The BCW and TDF were used to (i) understand the behavior (through literature review), (ii) identify intervention options (through the TDF-intervention function mapping table), (iii) select content and implementation options [through behavior change technique (BCT) taxonomy and literature review], and (iv) finalize the intervention content (through expert consultation, patient and public involvement and engagement, and piloting). A systematic iterative process was followed to design the intervention by following the steps recommended by the BCW. This systematic process identified 10 relevant TDF domains to encourage engagement in physical activity among Chinese children: knowledge, memory, attention and decision processes, social influences, environmental context and resources, beliefs about capabilities, beliefs about consequences, social rofessional role and identity, emotions, and physical skills. It resulted in the selection of seven intervention functions (education, persuasion, environmental restricting, modeling, enablement, training, and incentivization) and 21 BCTs in the program, delivered over a period of 16 weeks. The BCW and TDF allowed an in-depth consideration of the physical activity behavior among Chinese children and provided a systematic framework for developing the intervention. A feasibility study is now being undertaken to determine its acceptability and utility.
Publisher: Elsevier BV
Date: 10-2013
Publisher: Springer Science and Business Media LLC
Date: 16-02-2018
DOI: 10.1038/S41598-018-21388-9
Abstract: Antarctic coastal polynyas are regions of persistent open water and are thought to be key bio-physical features within the sea-ice zone. However, their use by the upper trophic levels of ecosystems remains unclear. A unique bio-physical dataset recorded by southern elephant seals reveals that East Antarctic polynyas are a key winter foraging habitat for male seals. During their post-moult trips from Isles Kerguelen to the Antarctic continental shelf, a total of 18 out of 23 seals visited 9 different polynyas, spending on average 25 ± 20% (up to 75%) of their total trip time inside polynyas. Changes in seal foraging and ing behaviours are observed inside polynyas as compared to outside polynyas. Two polynya usages by seals are observed for the inactive and active polynya phases, pointing to different seasonal peaks in prey abundance. During the active polynya phase, we link seal foraging behaviour to changes in the physical stability of the water-column, which likely impact the seasonal biological dynamics within polynyas.
Publisher: American Geophysical Union (AGU)
Date: 29-11-2022
DOI: 10.1029/2022JC018804
Abstract: Coastal polynyas are key formation regions for dense shelf water (DSW) that ultimately contributes to the ventilation of the ocean abyss. However, not all polynyas form DSW. We examine how the physiographic setting, water‐mass distribution and transformation, water column stratification, and sea‐ice production regulate DSW formation in four East Antarctic coastal polynyas. We use a salt budget to estimate the relative contribution of sea‐ice production and lateral advection to the monthly change in salinity in each polynya. DSW forms in Mackenzie polynya due to a combination of physical features (shallow water depth and a broad continental shelf) and high sea‐ice production. Sea‐ice formation begins early (March) in Mackenzie polynya, counteracting fresh advection and establishing a salty mixed layer in autumn that preconditions the water column for deep convection in winter. Sea‐ice production is moderate in the other three polynyas, but saline DSW is not formed (a fresh variety is formed in the Barrier polynya). In the Shackleton polynya, brine rejection during winter is insufficient to overcome the very fresh autumn mixed layer. In Vincennes Bay, a strong inflow of modified Circumpolar Deep Water stratifies the water column, hindering deep convection and DSW formation. Our study highlights that DSW formation in a given polynya depends on a complex combination of factors, some of which may be strongly altered under a changing climate, with potentially important consequences for the ventilation of the deep ocean, the global meridional overturning circulation, and the transport of ocean heat to Antarctic ice shelves.
Publisher: Elsevier BV
Date: 03-2022
Publisher: The Company of Biologists
Date: 12-02-2016
DOI: 10.1242/BIO.016659
Abstract: Dive characteristics and e shape are often used to infer foraging success in pinnipeds. However, these inferences have not been directly validated in the field with video, and it remains unclear if this method can be applied to benthic foraging animals. This study assessed the ability of e characteristics from time-depth recorders (TDR) to predict attempted prey capture events (APC) that were directly observed on animal-borne video in Australian fur seals (Arctocephalus pusillus doriferus, n=11). The most parsimonious model predicting the probability of a e with ≥1 APC on video included only descent rate as a predictor variable. The majority (94%) of the 389 total APC were successful, and the majority of the es (68%) contained at least one successful APC. The best model predicting these successful es included descent rate as a predictor. Comparisons of the TDR model predictions to video yielded a maximum accuracy of 77.5% in classifying es as either APC or non-APC or 77.1% in classifying es as successful verses unsuccessful. Foraging intensity, measured as either total APC per e or total successful APC per e, was best predicted by bottom duration and ascent rate. The accuracy in predicting total APC per e varied based on the number of APC per e with maximum accuracy occurring at 1 APC for both total (54%) and only successful APC (52%). Results from this study linking verified foraging es to e characteristics potentially opens the door to decades of historical TDR datasets across several otariid species.
Publisher: Public Library of Science (PLoS)
Date: 25-03-2015
Publisher: Cold Spring Harbor Laboratory
Date: 04-05-2018
DOI: 10.1101/314690
Abstract: Like many species, movement patterns of southern elephant seals ( Mirounga leonina ) are being influenced by long-term environmental change. These seals migrate up to 4000 km from their breeding colonies, foraging for months in a variety of Southern Ocean habitats. Understanding how movement patterns vary with environmental features and how these relationships differ among in iduals employing different foraging strategies can provide insight into foraging performance at a population level. We apply new fast-estimation tools to fit mixed effects within a random walk movement model, rapidly inferring among-in idual variability in southern elephant seal environment-movement relationships. We found that seals making foraging trips to the sea-ice on or near the Antarctic continental shelf consistently reduced speed and directionality (move persistence) with increasing sea ice coverage and had variable responses to chlorophyll a concentration, whereas seals that foraged pelagically reduced move persistence in regions where circumpolar deep water shoaled. Given future climate scenarios, pelagic foragers may encounter more productive habitat but sea-ice foragers may see reduced habitat availability. Our approach is scalable to large telemetry data sets and allows flexible combinations of mixed effects to be evaluated via model selection, thereby illuminating the ecological context of animal movements that underlie habitat use.
Publisher: Wiley
Date: 06-2011
DOI: 10.1890/09-1299.1
Abstract: Predators are thought to reduce travel speed and increase turning rate in areas where resources are relatively more abundant, a behavior termed "area-restricted search." However, evidence for this is rare, and few empirical data exist for large predators. Animals exhibiting foraging site fidelity could also be spatially aware of suitable feeding areas based on prior experience changes in movement patterns might therefore arise from the anticipation of higher prey density. We tested the hypothesis that regions of area-restricted search were associated with a higher number of daily speed spikes (a proxy for potential prey encounter rate) and foraging success in southern elephant seals (Mirounga leonina), a species exhibiting both area-restricted searches and high interannual foraging site fidelity. We used onshore morphological measurements and ing data from archival tags deployed during winter foraging trips. Foraging success was inferred from in situ changes in relative lipid content derived from measured changes in buoyancy, and first-passage time analysis was used to identify area-restricted search behavior. Seals exhibited relatively direct southerly movement on average, with intensive search behavior predominantly located at the distal end of tracks. The probability of being in search mode was positively related to changes in relative lipid content thus, intensively searched areas were associated with the highest foraging success. However, there was high foraging success during the outward transit even though seals moved through quickly without slowing down and increasing turning rate to exploit these areas. In addition, the probability of being in search mode was negatively related to the number of daily speed spikes. These results suggest that movement patterns represent a response to prior expectation of the location of predictable and profitable resources. Shelf habitat was 4-9 times more profitable than the other habitats, emphasizing the importance of the East Antarctic shelf for this and other predators in the region. We have provided rare empirical data with which to investigate the relationship between predator foraging strategy and prey encounter/ foraging success, underlining the importance of inferring the timing and spatial arrangement of successful food acquisition for interpreting foraging strategies correctly.
Publisher: Wiley
Date: 13-03-2021
DOI: 10.1002/ECE3.7337
Publisher: Oxford University Press (OUP)
Date: 2004
DOI: 10.1016/J.ICESJMS.2004.07.026
Abstract: Stomach contents were collected from 36 sperm whales (Physeter macrocephalus) involved in two mass stranding events during February 1998 along the west coastline of Tasmania, Australia. Contents were dominated by oceanic cephalopods, with a total of 101 883 cephalopod beaks representing 48 species from 14 families of Teuthids, two species from two families of Octopods, and a single V yromorph species identified. Species ersity was higher in these animals than other sperm whales studied in the southern hemisphere, with s les containing an average of (±s.d.) 28.4 ± 11.1 species per s le. Diet s les were dominated by subtropical and muscular cephalopod species. Members of the family Histioteuthidae were the most important numerically, and were also important in terms of estimated reconstituted mass, although members of the Onychoteuthidae were the most dominant species in s les in terms of estimated reconstituted mass. Other families numerically important to species composition included the cranchiid, lepidoteuthid, onychoteuthid, and pholidoteuthid families, while the architeuthid, pholidoteuthid, and ommastrephid families were also important in terms of reconstituted mass. Cephalopod species composition varied with stranding site and with sex, but not with age. However, differences did not represent systemic variation with groups marked by high in idual variability. Lower rostral lengths of all cephalopod species ranged from 1.3 to 40.7 mm. Calculated dorsal mantle lengths from all species ranged from 10.7 to 2640.7 mm (mean ± s.d. = 233.7 ± 215.7 mm) and estimated wet weights of cephalopod prey ranged from 2.7 to 110 233.1 g (mean ± s.d. = 828.3 ± 3073.6 g). While there were differences in the size of some cephalopod species between stranding sites and with age, this was marked by high in idual variability. Differences in diet composition and prey size between sperm whales reflect in idual variability in foraging success and perhaps also foraging groups related to the social structure of this species.
Publisher: Springer Science and Business Media LLC
Date: 24-02-2013
DOI: 10.1038/NGEO1738
Publisher: The Oceanography Society
Date: 06-2017
Publisher: American Geophysical Union (AGU)
Date: 03-12-2013
DOI: 10.1002/2013GL058304
Abstract: Over the last decade, several hundred seals have been equipped with conductivity‐temperature‐depth sensors in the Southern Ocean for both biological and physical oceanographic studies. A calibrated collection of seal‐derived hydrographic data is now available, consisting of more than 165,000 profiles. The value of these hydrographic data within the existing Southern Ocean observing system is demonstrated herein by conducting two state estimation experiments, differing only in the use or not of seal data to constrain the system. Including seal‐derived data substantially modifies the estimated surface mixed‐layer properties and circulation patterns within and south of the Antarctic Circumpolar Current. Agreement with independent satellite observations of sea ice concentration is improved, especially along the East Antarctic shelf. Instrumented animals efficiently reduce a critical observational gap, and their contribution to monitoring polar climate variability will continue to grow as data accuracy and spatial coverage increase.
Publisher: Wiley
Date: 22-02-2016
Publisher: Wiley
Date: 12-07-2017
DOI: 10.1111/GCB.13776
Abstract: Understanding ergent biological responses to climate change is important for predicting ecosystem level consequences. We use species habitat models to predict the winter foraging habitats of female southern elephant seals and investigate how changes in environmental variables within these habitats may be related to observed decreases in the Macquarie Island population. There were three main groups of seals that specialized in different ocean realms (the sub-Antarctic, the Ross Sea and the Victoria Land Coast). The physical and climate attributes (e.g. wind strength, sea surface height, ocean current strength) varied amongst the realms and also displayed different temporal trends over the last two to four decades. Most notably, sea ice extent increased on average in the Victoria Land realm while it decreased overall in the Ross Sea realm. Using a species distribution model relating mean residence times (time spent in each 50 × 50 km grid cell) to 9 climate and physical co-variates, we developed spatial predictions of residence time to identify the core regions used by the seals across the Southern Ocean from 120°E to 120°W. Population size at Macquarie Island was negatively correlated with ice concentration within the core habitat of seals using the Victoria Land Coast and the Ross Sea. Sea ice extent and concentration is predicted to continue to change in the Southern Ocean, having unknown consequences for the biota of the region. The proportion of Macquarie Island females (40%) utilizing the relatively stable sub-Antarctic region, may buffer this population against longer-term regional changes in habitat quality, but the Macquarie Island population has persistently decreased (-1.45% per annum) over seven decades indicating that environmental changes in the Antarctic are acting on the remaining 60% of the population to impose a long-term population decline in a top Southern Ocean predator.
Publisher: Wiley
Date: 23-11-2017
Abstract: In iteroparous species, intermittent breeding is an important life-history tactic that can greatly affect animal population growth and viability. Despite its importance, few studies have quantified the consequences of breeding pauses on lifetime reproductive output, principally because calculating lifetime reproductive output requires knowledge of each in idual's entire reproductive history. This information is extremely difficult to obtain in wild populations. We applied novel statistical approaches that account for uncertainty in state assessment and in idual heterogeneity to an 18-year capture-recapture dataset of 6,631 female southern elephant seals from Macquarie Island. We estimated survival and breeding probabilities, and investigated the consequences of intermittent breeding on lifetime reproductive output. We found consistent differences in females' demographic performance between two heterogeneity classes. In particular, breeding imbued a high cost on survival in the females from the heterogeneity class 2, assumed to be females of lower quality. In idual quality also appeared to play a major role in a female's decision to skip reproduction with females of poorer quality more likely to skip breeding events than females of higher quality. Skipping some breeding events allowed females from both heterogeneity classes to increase lifetime reproductive output over females that bred annually. However, females of lower quality produced less offspring over their lifetime. Intermittent breeding seems to be used by female southern elephant seals as a tactic to offset reproductive costs on survival and enhance lifetime reproductive output but remains unavoidable and driven by in idual-specific constraints in some other females.
Publisher: Oxford University Press (OUP)
Date: 13-04-2004
Publisher: Elsevier BV
Date: 04-2020
Publisher: Wiley
Date: 31-08-2017
DOI: 10.1002/AQC.2805
Publisher: Public Library of Science (PLoS)
Date: 07-12-2017
Publisher: Frontiers Media SA
Date: 10-04-2015
Publisher: Proceedings of the National Academy of Sciences
Date: 26-02-2018
Abstract: Understanding the key drivers of animal movement is crucial to assist in mitigating adverse impacts of anthropogenic activities on marine megafauna. We found that movement patterns of marine megafauna are mostly independent of their evolutionary histories, differing significantly from patterns for terrestrial animals. We detected a remarkable convergence in the distribution of speed and turning angles across organisms ranging from whales to turtles (epitome for the slowest animals on land but not at sea). Marine megafauna show a prevalence of movement patterns dominated by search behavior in coastal habitats compared with more directed, ballistic movement patterns when the animals move across the open ocean. The habitats through which they move will therefore need to be considered for effective conservation.
Publisher: Wiley
Date: 20-05-2021
DOI: 10.1002/EAP.2343
Abstract: Quantifying the links between the marine environment, prey occurrence, and predator distribution is the first step towards identifying areas of biological importance for marine spatial planning. Events such as marine heatwaves result in an anomalous change in the physical environment, which can lead to shifts in the structure, biomass, and distribution of lower trophic levels. As central‐place foragers, seabirds are vulnerable to changes in their foraging grounds during the breeding season. We first quantified spatiotemporal variability in the occurrence and biomass of prey in response to an abrupt change in oceanography as a result of a marine heatwave event. Secondly, using multivariate techniques and machine learning, we investigated if differences in the foraging technique and prey of seabirds resulted in varying responses to changes in prey occurrence and the environment over a 2.5‐yr period. We found that the main variables correlated with seabird distribution were also important in structuring the occurrence and biomass of prey sea‐surface temperature (SST), current speed, mixed‐layer depth, and bathymetry. Both zooplankton biomass and the occurrence of fish schools exhibited negative relationships with temperature, and temperature was subsequently an important variable in determining seabird distribution. We were able to establish correlations between the distribution of prey and the spatiotemporal distribution of albatross, little penguins and common‐ ing petrels. We were unable to find a correlation between the distribution of prey and that of short‐tailed shearwaters and fairy prions. For high‐use coastal areas, the delineation of important foraging regions is essential to balance human use of an area with the needs of marine predators, particularly seabirds.
Publisher: Springer Science and Business Media LLC
Date: 27-03-2007
Abstract: Determining the relative contribution of intrinsic and extrinsic factors to fluctuations in population size, trends and demographic composition is analytically complex. It is often only possible to examine the combined effects of these factors through measurements made over long periods, spanning an array of population densities or levels of food availability. Using age-structured mark-recapture models and datasets spanning five decades (1950–1999), and two periods of differing relative population density, we estimated age-specific probabilities of survival and examined the combined effects of population density and environmental conditions on juvenile survival of southern elephant seals at Macquarie Island. First-year survival decreased with density during the period of highest population size, and survival increased during years when the Southern Oscillation Index (SOI) anomaly (deviation from a 50-year mean) during the mother's previous foraging trip to sea was positive (i.e., El Niño). However, when environmental stochasticity and density were considered together, the effect of density on first-year survival effectively disappeared. Ignoring density effects also leads to models placing too much emphasis on the environmental conditions prevailing during the naïve pup's first year at sea. Our analyses revealed that both the state of the environment and population density combine to modify juvenile survival, but that the degree to which these processes contributed to the variation observed was interactive and complex. This underlines the importance of evaluating the relative contribution of both the intrinsic and extrinsic factors that regulate animal populations because false conclusions regarding the importance of population regulation may be reached if they are examined in isolation.
Publisher: Springer Science and Business Media LLC
Date: 15-03-2016
Publisher: Springer Science and Business Media LLC
Date: 18-05-2020
DOI: 10.1038/S41598-020-64662-5
Abstract: Invasive species present a major conservation threat globally and nowhere are their affects more pronounced than in island ecosystems. Determining how native island populations respond demographically to invasive species can provide information to mitigate the negative effects of invasive species. Using 20 years of mark-recapture data from three sympatric species of albatrosses (black-browed Thalassarche melanophris , grey-headed T. chrysostoma , and light-mantled albatrosses Phoebetria palpebrata ), we quantified the influence of invasive European rabbits Oryctolagus cuniculus and extreme weather patterns on breeding probability and success. Temporal variability in rabbit density explained 33–76% of the variability in breeding probability for all three species, with severe decreases in breeding probability observed after a lag period following highest rabbit numbers. For black-browed albatrosses, the combination of extreme rainfall and high rabbit density explained 33% of total trait variability and dramatically reduced breeding success. We showed that invasive rabbits and extreme weather events reduce reproductive output in albatrosses and that eliminating rabbits had a positive effect on albatross reproduction. This illustrates how active animal management at a local breeding site can result in positive population outcomes even for wide ranging animals like albatrosses where influencing vital rates during their at-sea migrations is more challenging.
Publisher: American Geophysical Union (AGU)
Date: 12-2021
DOI: 10.1029/2021JC017748
Abstract: We provide a detailed description of the spatial distribution, seasonality and transformation of the main water masses within MacKenzie Polynya (MP) in Prydz Bay, East Antarctica, using data from instrumented southern elephant seals. Dense Shelf Water (DSW) formation in MP shows large spatial variability that is related to the (a) local bathymetry, (b) water column preconditioning from the presence/absence of different water masses, and (c) proximity to the Amery Ice Shelf meltwater outflow. MP exhibits sustained sea ice production and brine rejection (thus, salinity increase) from April to October. However, new DSW is only formed from June onward, when the mixed layer deepens and convection is strong enough to break the stratification set by Antarctic Surface Water above and Ice Shelf Water below. We found no evidence of DSW export from MP to Darnley polynya, as previously suggested. Rather, our observations suggest some DSW formed in Darnley Polynya may drain toward the western Prydz Bay. Then, DSW is exported offshore from Prydz Bay through the Prydz Channel. The interplay between sea ice formation, meltwater input, and sea floor topography is likely to explain why some coastal polynyas form more DSW than others, as well as the temporal variability in DSW formation within a particular polynya.
Publisher: Elsevier BV
Date: 05-0008
Publisher: University of Chicago Press
Date: 1998
DOI: 10.1086/515890
Abstract: Heart rate, swimming speed, and ing behaviour were recorded simultaneously for an adult female southern elephant seal during her postbreeding period at sea with a Wildlife Computers heart-rate time depth recorder and a velocity time depth recorder. The errors associated with data storage versus real-time data collection of these data were analysed and indicated that for events of short duration (i.e., less than 10 min or 20 s ling intervals) serious biases occur. A simple model for estimating oxygen consumption based on the estimated oxygen stores of the seal and the assumption that most, if not all, es were aerobic produced a mean ing metabolic rate of 3.64 mL O2 kg-1, which is only 47% of the field metabolic rate estimated from allometric models. Mechanisms for reducing oxygen consumption while ing include cardiac adjustments, indicated by reductions in heart rate on all es, and the maintenance of swimming speed at near the minimum cost of transport for most of the submerged time. Heart rate during ing was below the resting heart rate while ashore in all es, and there was a negative relationship between the duration of a e and the mean heart rate during that e for es longer than 13 min. Mean heart rates declined from 40 beats min-1 for es of 13 min to 14 beats min-1 for es of 37 min. Mean swimming speed per e was 2.1 m s-1, but this also varied with e duration. There were slight but significant increases in mean swimming speeds with increasing e depth and duration. Both ascent and descent speeds were also higher on longer es.
Publisher: Elsevier BV
Date: 02-2016
Publisher: Wiley
Date: 26-04-2012
Publisher: Wiley
Date: 06-02-2019
Abstract: Age structure is a fundamental aspect of animal population biology. Age is strongly related to in idual physiological condition, reproductive potential and mortality rate. Currently, there are no robust molecular methods for age estimation in birds. Instead, in iduals must be ringed as chicks to establish known-age populations, which is a labour-intensive and expensive process. The estimation of chronological age using DNA methylation (DNAm) is emerging as a robust approach in mammals including humans, mice and some non-model species. Here, we quantified DNAm in whole blood s les from a total of 71 known-age Short-tailed shearwaters (Ardenna tenuirostris) using digital restriction enzyme analysis of methylation (DREAM). The DREAM method measures DNAm levels at thousands of CpG dinucleotides throughout the genome. We identified seven CpG sites with DNAm levels that correlated with age. A model based on these relationships estimated age with a mean difference of 2.8 years to known age, based on validation estimates from models created by repeated s ling of training and validation data subsets. Longitudinal observation of in iduals re-s led over 1 or 2 years generally showed an increase in estimated age (6/7 cases). For the first time, we have shown that epigenetic changes with age can be detected in a wild bird. This approach should be of broad interest to researchers studying age biomarkers in non-model species and will allow identification of markers that can be assessed using targeted techniques for accurate age estimation in large population studies.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2006
Publisher: Informa UK Limited
Date: 02-07-2016
Publisher: Inter-Research Science Center
Date: 10-10-2019
DOI: 10.3354/MEPS13113
Publisher: Wiley
Date: 26-01-2023
Abstract: Animal tracking data are indispensable for understanding the ecology, behaviour and physiology of mobile or cryptic species. Meaningful signals in these data can be obscured by noise due to imperfect measurement technologies, requiring rigorous quality control as part of any comprehensive analysis. State–space models are powerful tools that separate signal from noise. These tools are ideal for quality control of error‐prone location data and for inferring where animals are and what they are doing when they record or transmit other information. However, these statistical models can be challenging and time‐consuming to fit to erse animal tracking data sets. The R package aniMotum eases the tasks of conducting quality control on and inference of changes in movement from animal tracking data. This is achieved via: (1) a simple but extensible workflow that accommodates both novice and experienced users (2) automated processes that alleviate complexity from data processing and model specification/fitting steps (3) simple movement models coupled with a powerful numerical optimization approach for rapid and reliable model fitting. We highlight aniMotum 's capabilities through three applications to real animal tracking data. Full R code for these and additional applications is included as Supporting Information, so users can gain a deeper understanding of how to use aniMotum for their own analyses.
Publisher: Elsevier BV
Date: 02-2015
Publisher: Springer Science and Business Media LLC
Date: 04-07-2023
DOI: 10.1038/S41467-023-38900-Z
Abstract: Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with in idual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.
Publisher: Elsevier BV
Date: 11-2007
Publisher: The Royal Society
Date: 07-05-2014
Abstract: As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal ( Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change ( r ) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from −0.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced ( R = 0.51) and (iii) was associated with sea-ice duration (SID) within the seals’ foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.
Publisher: Springer Science and Business Media LLC
Date: 11-09-2019
DOI: 10.1186/S12898-019-0252-X
Abstract: To understand and predict the distribution of foragers, it is crucial to identify the factors that affect in idual movement decisions at different scales. In iduals are expected to adjust their foraging movements to the hierarchical spatial distribution of resources. At a small local scale, spatial segregation in foraging habitat happens among in iduals of closely situated colonies. If foraging segregation is due to differences in distribution of resources, we would expect segregated foraging areas to have ergent habitat characteristics. We investigated how environmental characteristics of preferred foraging areas differ between two closely situated Subantarctic fur seal ( Arctocephalus tropicalis ) colonies and a single Antarctic fur seal ( A. gazella ) colony that forage in different pelagic areas even though they are located well within each other’s foraging range. We further investigated the influence of the seasonal cycle on those environmental factors. This study used tracking data from 121 adult female Subantarctic and Antarctic fur seals, collected during summer and winter (2009–2015), from three different colonies. Boosted Regression Tree species distribution models were used to determine key environmental variables associated with areas of fur seal restricted search behaviour. There were no differences in the relative influence of key environmental variables between colonies and seasons. The variables with the most influence for each colony and season were latitude, longitude and magnitude of sea-currents. The influence of latitude and longitude is a by-product of the species’ distinct foraging areas, despite the close proximity ( 25 km) of the colonies. The predicted potential foraging areas for each colony changed from summer to winter, reflecting the seasonal cycle of the Southern Ocean. The model predicted that the potential foraging areas of females from the three colonies should overlap, and the fact they do not in reality indicates that factors other than environmental are influencing the location of each colony’s foraging area. The results indicated that small scale spatial segregation of foraging habitats is not driven by bottom-up processes. It is therefore important to also consider other potential drivers, e.g. competition, information transfer, and memory, to understand animal foraging decisions and movements.
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/MF01218
Abstract: Antarctic Arctocephalus gazella and subantarctic Arctocephalus tropicalis fur seals breed sympatrically at Macquarie Island. The two species have different lactation strategies, the former rearing its pup in 4 months and the latter taking 10 months. The diet and at-sea foraging behaviour of these sympatric species was compared during the austral summer period when their pup rearing period overlapped. The prey of the two fur seal species was very similar, with fish dominating the diet. The myctophid, Electrona subaspera, was the main prey item (93.9%) in all months of the study. There were no major differences in the ing behaviour between species. Both species foraged north of the island parallel to the Macquarie Ridge. Foraging activity was concentrated at two sites: (i) within 30�km north of the island and (ii) at 60 km north. Most locations for overnight foraging trips were within 10 km of the colonies. The different lactation strategies of A. gazella and A. tropicalis allowed for flexibility in foraging behaviour. At Macquarie Island, the local marine environmental conditions have resulted in similar foraging behaviour for both species.
Publisher: Wiley
Date: 2005
Publisher: Wiley
Date: 12-2007
DOI: 10.1002/AQC.915
Publisher: Proceedings of the National Academy of Sciences
Date: 19-08-2008
Abstract: Polar regions are particularly sensitive to climate change, with the potential for significant feedbacks between ocean circulation, sea ice, and the ocean carbon cycle. However, the difficulty in obtaining in situ data means that our ability to detect and interpret change is very limited, especially in the Southern Ocean, where the ocean beneath the sea ice remains almost entirely unobserved and the rate of sea-ice formation is poorly known. Here, we show that southern elephant seals ( Mirounga leonina ) equipped with oceanographic sensors can measure ocean structure and water mass changes in regions and seasons rarely observed with traditional oceanographic platforms. In particular, seals provided a 30-fold increase in hydrographic profiles from the sea-ice zone, allowing the major fronts to be mapped south of 60°S and sea-ice formation rates to be inferred from changes in upper ocean salinity. Sea-ice production rates peaked in early winter (April–May) during the rapid northward expansion of the pack ice and declined by a factor of 2 to 3 between May and August, in agreement with a three-dimensional coupled ocean–sea-ice model. By measuring the high-latitude ocean during winter, elephant seals fill a “blind spot” in our s ling coverage, enabling the establishment of a truly global ocean-observing system.
Publisher: SAGE Publications
Date: 15-05-2022
DOI: 10.1177/17579139221094750
Abstract: Development and rollout of vaccines offers the best opportunity for population protection against the SARS-CoV-2 (COVID-19) virus. However, hesitancy towards the vaccines might impede successful uptake in the United Kingdom, particularly in young adults who demonstrate the highest rates of hesitancy. This prospective study explored COVID-19 vaccine hesitancy in young adults and whether the reasons behind these attitudes changed during the initial stages of the United Kingdom’s vaccine rollout. Data on vaccination intention were collected from a British university student cohort at three time points: October 2020, February 2021, and March 2021. This online survey included items on intention to receive a vaccine and a free-text response for the reasons behind this intention. Cochran’s Q tests examined changes in rates of hesitancy and acceptance over time and free-text responses were analysed thematically. At baseline, 893 students provided data, with 476 participants completing all three time points. Hesitancy declined over time, with 29.4% of participants expressing hesitancy at baseline, reducing to 9.1% at wave 2 and 5.9% at wave 3. The most commonly endorsed themes for those willing to accept a vaccine were self-protection against COVID-19 and pro-social reasons, including protecting the population or unspecific others, and ending the pandemic/returning to normal life. The most commonly endorsed hesitancy themes related to ‘confidence’ in the vaccines and potential personal risk, including insufficient testing/scientific evidence, concern about side effects, and long-term effects. These reasons remained the most commonly endorsed at both waves 2 and 3. While a decline in hesitancy was observed over time, the key reasons behind both vaccine acceptance and hesitancy remained consistent. Reasons behind hesitancy aligned with those of the general public, providing support for the use of generalist interventions. Pro-social reasons frequently underpinned vaccine acceptance, so cohort-specific interventions targeting those factors may be of benefit.
Publisher: Elsevier BV
Date: 09-2012
Publisher: Inter-Research Science Center
Date: 17-01-2019
DOI: 10.3354/MEPS12811
Publisher: Wiley
Date: 05-2006
Publisher: Wiley
Date: 11-08-2008
Publisher: Frontiers Media SA
Date: 17-08-2017
Publisher: Elsevier BV
Date: 02-2013
Publisher: Wiley
Date: 30-06-2005
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.DIABRES.2019.01.026
Abstract: The Problem Areas In Diabetes (PAID) questionnaire is widely used to assess emotional distress related to living with diabetes, although it is lengthy for routine clinical use. Our aim was to determine whether the original 20-item PAID questionnaire can be abbreviated, whilst maintaining its reliability, validity and utility. We analysed data from the UK DAFNE (Dose Adjustment For Normal Eating) education programme for adults with Type 1 diabetes. Data were analysed at baseline (n = 1547) and 1-year post intervention (n = 846). Exploratory factor analysis (EFA) with principal axis factoring method was used to examine PAID responses within a random half of the baseline data (n = 746). Then, two confirmatory factor analyses (CFA) were conducted using the remaining baseline (n = 801) and 1-year data. Reliability, predictive validity, convergent validity and responsiveness were also examined. Based on the EFA results, which were corroborated by CFA, an 11-item PAID questionnaire was identified with a cut-off score of 18 indicating severe diabetes distress. In the current s le, this brief version had high internal consistency (Cronbach's α = 0.93). Predictive validity was demonstrated with the PAID-11 identifying severe diabetes distress from the original 20-item measure, with 95% sensitivity and 96% specificity. Convergent validity was demonstrated by strong positive correlations with HADS anxiety and depressive symptoms (average r = 0.65 and r = 0.55, respectively), while ergent validity was shown with weaker correlations with EQ5D health status (average r = 0.37). Based on present results, PAID-11 appears to be a valid and reliable measure, which seems suitable for use as a brief tool for the detection of diabetes distress in adults with type 1 diabetes. Importantly, this tool may reduce participant burden in multi-measure studies. However, further studies are urgently needed to determine the validity and utility of PAID-11 beyond the UK DAFNE population.
Publisher: Wiley
Date: 12-04-2005
Publisher: Oxford University Press (OUP)
Date: 2010
Publisher: Public Library of Science (PLoS)
Date: 13-09-2017
Publisher: IOP Publishing
Date: 12-2020
Abstract: Marine debris is a growing threat to hundreds of marine animal species. To understand the consequences of marine debris to wildlife populations, studies must go beyond reporting the incidence of wildlife and debris interactions and aim to quantify the harm resulting from these interactions. Tubenosed seabirds are globally threatened, with a near universal risk of debris ingestion and an unquantified risk of mortality due to eating plastics. In this paper, we explore the mortality risk narrative due to the acute effects of debris ingestion, and quantify behavioural and ecological factors including age, diet and foraging method. We examined ingested debris loads, types and mortality of 972 adult and immature seabirds across 17 albatross, shearwater and prion species in a global seabird bio ersity hotspot. Though age and foraging method interact to influence the incidence and number of items ingested, age and diet were the most important factors influencing mortality. Mortality is influenced by debris load and type of debris ingested and there is selectivity for items that visually resemble a seabird’s prey. Immature birds that forage on cephalopods are more likely to ingest and die from eating debris than are adults. Conversely, the risk of death to seabirds that forage on crustaceans is linked to the number of plastic items ingested and is higher in adults. Debris ingestion is an under-recognised cause of tubenose mortality and is likely negatively affecting rare and threatened species.
Publisher: Inter-Research Science Center
Date: 03-04-2006
DOI: 10.3354/MEPS310077
Publisher: Inter-Research Science Center
Date: 18-04-2019
DOI: 10.3354/MEPS12922
Publisher: Inter-Research Science Center
Date: 29-05-2018
DOI: 10.3354/MEPS11947
Publisher: Elsevier BV
Date: 02-2008
Publisher: American Geophysical Union (AGU)
Date: 19-06-2021
DOI: 10.1029/2020GL091206
Abstract: Antarctic krill (krill) are important within Southern Ocean ecosystems and support an expanding fishery. Toward understanding krill's response to environmental change, it is necessary to identify regions that support high krill larval production (spawning habitat). We develop a mechanistic model combining thermal and food requirements for krill egg production, with predation pressure post‐spawning, to predict regions of high‐quality spawning habitat. We optimize our model regionally and generate circumpolar predictions of spawning habitat quality. Our results indicate the southwest Atlantic accounts for almost half of all predicted high‐quality spawning habitat. Small‐scale management units (SSMUs) around the Antarctic Peninsula had high coverage of high‐quality spawning habitat. In contrast, the remaining SSMUs (except around South Georgia) were poorly covered, suggestive of population sinks reliant on input from external sources upstream. This implies strong potential for downstream impacts of fishing in key spawning areas, with implications for management of SSMUs and the krill fishery.
Publisher: Springer Science and Business Media LLC
Date: 22-06-2017
Abstract: Predicting population declines is a key challenge in the face of global environmental change. Abundance-based early warning signals have been shown to precede population collapses however, such signals are sensitive to the low reliability of abundance estimates. Here, using historical data on whales harvested during the 20th century, we demonstrate that early warning signals can be present not only in the abundance data, but also in the more reliable body size data of wild populations. We show that during the period of commercial whaling, the mean body size of caught whales declined dramatically (by up to 4 m over a 70-year period), leading to early warning signals being detectable up to 40 years before the global collapse of whale stocks. Combining abundance and body size data can reduce the length of the time series required to predict collapse, and decrease the chances of false positive early warning signals.
Publisher: Springer Science and Business Media LLC
Date: 18-04-2020
Publisher: Wiley
Date: 20-10-2016
DOI: 10.1002/ECE3.2530
Publisher: Canadian Science Publishing
Date: 02-2005
DOI: 10.1139/Z05-013
Abstract: Some phocid seal ing-behaviour studies have identified es characterised by a period of passive drifting through the water column, rather than active locomotion. During these "drift es" seals are thought to preferentially direct energy towards processing of food, lactate, or renal metabolites rather than to active propulsion. We describe the first drift es reported in an otariid, the New Zealand fur seal (Arctocephalus forsteri (Lesson, 1828)), studied at Kangaroo Island in South Australia. Not all males in the study undertook drift es and those that did were significantly heavier than those that did not, suggesting that body size may influence the propensity to drift e in New Zealand fur seals. Drift es lasted 6.0 ± 1.78 min and had passive drift segments of 3.5 ± 1.5 min, during which seals showed a negative change in depth (i.e., sinking) of 0.14 ± 0.05 m/s. Drift es occurred at night and were possibly undertaken to avoid near-surface predators and to process food, lactate, or renal metabolites while resting.
Publisher: Springer Science and Business Media LLC
Date: 06-11-2008
Publisher: Wiley
Date: 13-08-2008
DOI: 10.1111/J.1365-2656.2008.01407.X
Abstract: 1. Identifying the spatial scales at which top marine predators forage is important for understanding oceanic ecosystems. Several methods quantify how in iduals concentrate their search effort along a given path. Among these, First-Passage Time (FPT) analysis is particularly useful to identify transitions in movement patterns (e.g. between searching and feeding). This method has mainly been applied to terrestrial animals or flying seabirds that have little or no vertical component to their foraging, so we examined the differences between classic FPT and a modification of this approach using the time spent at the bottom of a e for characterizing the foraging activity of a ing predator: the southern elephant seal. 2. Satellite relayed data loggers were deployed on 20 in iduals during three successive summers at the Kerguelen Islands, providing a total of 72 978 es from eight juvenile males and nine adult females. 3. Spatial scales identified using the time spent at the bottom of a e ( = 68.2 +/- 42.1 km) were smaller than those obtained by the classic FPT analysis ( = 104.7 +/- 67.3 km). Moreover, foraging areas identified using the new approach clearly overlapped areas where in iduals increased their body condition, indicating that it accurately reflected the foraging activity of the seals. 4. These results suggest that incorporating the vertical dimension into FPT provides a different result to the surface path alone. Close to the Antarctic continent, within the pack-ice, sinuosity of the path could be explained by a high sea-ice concentration (restricting elephant seal movements), and was not necessarily related to foraging activity. 5. Our approach distinguished between actual foraging activity and changes in behaviour induced by the physical environment like sea ice, and could be applied to other ing predators. Inclusion of ing parameters appears to be essential to identify the spatial scale of foraging areas of ing animals.
Publisher: Wiley
Date: 20-12-2016
DOI: 10.1002/ECE3.2652
Publisher: Elsevier BV
Date: 06-2002
DOI: 10.1016/S1095-6433(02)00030-2
Abstract: The estimation of milk consumption in free-ranging seals using tritium dilution techniques makes the key assumption that the animals drink no pre-formed water during the experimental period. However, frequent observations of unweaned Antarctic fur seal pups drinking water at Iles Kerguelen necessitated the testing of this assumption. We estimated water flux rates of 30 pups (10.7+/-0.3 kg) in four experimental groups by isotopic dilution over 4 days. The groups were: (1) pups held in an open air enclosure without access to water to estimate fasting metabolic water production (MWP) (2) free-ranging pups not administered additional water (3) pups held in an open air enclosure and given a total of 300 ml of fresh water to verify technique accuracy and (4) free-ranging pups given 200 ml of fresh water. Pups without access to water exhibited water flux rates (20.5+/-0.8 ml kg(-1)d(-1)), which were significantly lower than those observed for the free-ranging group (33.0+/-1.7 ml kg(-1) d(-1)). Mean estimated pre-formed water intake for the free-ranging experimental groups was 12.6 ml kg(-1) d(-1). Thus, MWP, measured as total water intake during fasting, may be significantly over-estimated in free-ranging Antarctic fur seal pups at Iles Kerguelen and at other sites and subsequently milk intake rates may be underestimated.
Publisher: Wiley
Date: 12-01-2017
Abstract: In mammals, maternal expenditure on offspring is a complex mix of several factors including the species' mating system, offspring sex and the condition and age of the mother. While theory suggests that in polygynous species mothers should wean larger male offspring than females when resources and maternal conditions allow, the evidence for this remains equivocal. Southern elephant seals are highly dimorphic, polygynous capital breeders existing in an environment with highly variable resources and should therefore provide clear evidence to support the theoretical expectations of differential maternal expenditure in male and female pups. We quantified maternal size (mass and length) and pup size at birth and weaning for 342 elephant seal mothers at Macquarie Island. The study was conducted over 11 years of contrasting sea-ice and Southern Annular Mode values, both indices of maternal prey resources. Overall, large females weaned male pups that weighed 17 kg (15·5%) more than female pups. Maternal condition varied by as much as 59 kg among years, and was positively related to Southern Annular Mode, and negatively to maximum sea-ice extent. Smaller mothers weaned relatively larger male pups under favourable conditions, this effect was less apparent for larger mothers. We developed a simple model linking environmental variation to maternal masses post-partum, followed by maternal masses post-partum to weaning masses and then weaning masses to pup survival and demonstrated that environmental conditions affected predicted survival so that the pups of small mothers had an estimated 7% increase in first year survival in 'good' vs. 'bad' years compared to 1% for female pups of large mothers. Co-occurrence of environmental quality and conservative reproductive tactics suggests that mothers retain substantial plasticity in maternal care, enhancing their lifetime reproductive success by adjusting reproductive expenditure relative to both prevailing environmental conditions and their own capabilities.
Publisher: Elsevier BV
Date: 09-2016
Publisher: Springer Science and Business Media LLC
Date: 08-03-2017
DOI: 10.1038/S41598-017-00165-0
Abstract: The growing number of large databases of animal tracking provides an opportunity for analyses of movement patterns at the scales of populations and even species. We used analytical approaches, developed to cope with “big data”, that require no ‘ a priori’ assumptions about the behaviour of the target agents, to analyse a pooled tracking dataset of 272 elephant seals ( Mirounga leonina ) in the Southern Ocean, that was comprised of ,000 location estimates collected over more than a decade. Our analyses showed that the displacements of these seals were described by a truncated power law distribution across several spatial and temporal scales, with a clear signature of directed movement. This pattern was evident when analysing the aggregated tracks despite a wide ersity of in idual trajectories. We also identified marine provinces that described the migratory and foraging habitats of these seals. Our analysis provides evidence for the presence of intrinsic drivers of movement, such as memory, that cannot be detected using common models of movement behaviour. These results highlight the potential for “big data” techniques to provide new insights into movement behaviour when applied to large datasets of animal tracking.
Publisher: Wiley
Date: 05-2016
DOI: 10.1002/ECS2.1213
Publisher: American Geophysical Union (AGU)
Date: 30-07-2021
DOI: 10.1029/2020JC016998
Abstract: Antarctic Bottom Water (AABW) production supplies the deep limb of the global overturning circulation and ventilates the deep ocean. While the Weddell and Ross Seas are recognized as key sites for AABW production, additional sources have been discovered in coastal polynya regions around East Antarctica, most recently at Vincennes Bay. Vincennes Bay, despite encompassing two distinct polynya regions, is considered the weakest source, producing Dense Shelf Water (DSW) only just dense enough to contribute to the lighter density classes of AABW found offshore. Here we provide the first detailed oceanographic observations of the continental shelf in Vincennes Bay (104‐111°E), using CTD data from instrumented elephant seals spanning from February to November of 2012. We find that Vincennes Bay has East Antarctica’s warmest recorded intrusions of modified Circumpolar Deep Water (mCDW) and that warm mCDW drives basal melt under Vanderford and Underwood ice shelves. Our study also provides the first direct observational evidence for the inflow of meltwater to this region, which increases stratification and hinders DSW formation, and thus AABW production. The Vincennes Bay glaciers, together with the Totten Glacier, drain part of the Aurora Basin, which holds up to 7 m of sea level rise equivalent. Our results highlight the vulnerability of the East Antarctic Ice Sheet to intrusions of mCDW.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Inter-Research Science Center
Date: 02-02-2010
DOI: 10.3354/ESR00257
Publisher: Springer Science and Business Media LLC
Date: 13-07-2022
DOI: 10.1038/S41597-022-01496-Y
Abstract: The global importance of mesopelagic fish is increasingly recognised, but they remain poorly studied. This is particularly true in the Southern Ocean, where mesopelagic fishes are both key predators and prey, but where the remote environment makes s ling challenging. Despite this, multiple national Antarctic research programs have undertaken regional s ling of mesopelagic fish over several decades. However, data are dispersed, and s ling methodologies often differ precluding comparisons and limiting synthetic analyses. We identified potential data holders by compiling a metadata catalogue of existing survey data for Southern Ocean mesopelagic fishes. Data holders contributed 17,491 occurrence and 11,190 abundance records from 4780 net hauls from 72 different research cruises. Data span across 37 years from 1991 to 2019 and include trait-based information (length, weight, maturity). The final dataset underwent quality control processes and detailed metadata was provided for each s ling event. This dataset can be accessed through Zenodo. Myctobase will enhance research capacity by providing the broadscale baseline data necessary for observing and modelling mesopelagic fishes.
Publisher: Springer Science and Business Media LLC
Date: 29-01-2019
DOI: 10.1038/S41598-018-37324-W
Abstract: Procellariiform seabirds are both the most threatened bird group globally, and the group with the highest incidence of marine debris ingestion. We examined the incidence and ecological factors associated with marine debris ingestion in Procellariiformes by examining seabirds collected at a global seabird hotspot, the Australasian - Southern Ocean boundary. We examined marine debris ingestion trends in 1734 in iduals of 51 Procellariform species, finding significant variation in the incidence of marine debris abundance among species. Variation in the incidence of marine debris ingestion between species was influenced by the taxonomy, foraging ecology, diet, and foraging range overlaps with oceanic regions polluted with marine debris. Among the ecological drivers of marine debris ingestion variability in Procellariiformes, we demonstrate that the combination of taxonomy, foraging method, diet, and exposure to marine debris are the most important determinants of incidence of ingestion. We use these results to develop a global forecast for Procellariiform taxa at the risk of highest incidence of marine debris ingestion. We find seabirds that forage at the surface especially by surface seizing, ing and filtering, those with a crustacean dominant diet, and those that forage in or near marine debris hotspots are at highest risk of debris ingestion. We predict that family with the highest risk are the storm petrels ( Hydrobatidae and Oceanitidae ). We demonstrate that the greater the exposure of high-risk groups to marine debris while foraging, the greater the incidence and number of marine debris items will be ingested.
Publisher: The Royal Society
Date: 22-06-2003
Publisher: The Royal Society
Date: 19-08-2020
Abstract: Changes in the foraging environment and at-sea distribution of southern elephant seals from Kerguelen Islands were investigated over a decade (2004–2018) using tracking, weaning mass, and blood δ 13 C values. Females showed either a sub-Antarctic or an Antarctic foraging strategy, and no significant shift in their at-sea distribution was detected between 2004 and 2017. The proportion of females foraging in sub-Antarctic versus Antarctic habitats did not change over the 2006–2018 period. Pup weaning mass varied according to the foraging habitat of their mothers. The weaning mass of sub-Antarctic foraging mothers' pups decreased by 11.7 kg over the study period, but they were on average 5.8 kg heavier than pups from Antarctic foraging mothers. Pup blood δ 13 C values decreased by 1.1‰ over the study period regardless of their sex and the presumed foraging habitat of their mothers. Together, these results suggest an ecological change is occurring within the Indian sector of the Southern Ocean with possible consequences on the foraging performance of southern elephant seals. We hypothesize that this shift in δ 13 C is related to a change in primary production and/or in the composition of phytoplankton communities, but this requires further multidisciplinary investigations.
Publisher: Elsevier BV
Date: 02-2003
Publisher: Springer Science and Business Media LLC
Date: 13-01-2005
Publisher: Wiley
Date: 30-11-2017
DOI: 10.1111/MMS.12456
Publisher: Wiley
Date: 14-07-2015
DOI: 10.1111/ECOG.01021
Publisher: Wiley
Date: 07-2004
Publisher: Springer Science and Business Media LLC
Date: 23-08-2016
DOI: 10.1038/NCOMMS12577
Abstract: A fourth production region for the globally important Antarctic bottom water has been attributed to dense shelf water formation in the Cape Darnley Polynya, adjoining Prydz Bay in East Antarctica. Here we show new observations from CTD-instrumented elephant seals in 2011–2013 that provide the first complete assessment of dense shelf water formation in Prydz Bay. After a complex evolution involving opposing contributions from three polynyas (positive) and two ice shelves (negative), dense shelf water (salinity 34.65–34.7) is exported through Prydz Channel. This provides a distinct, relatively fresh contribution to Cape Darnley bottom water. Elsewhere, dense water formation is hindered by the freshwater input from the Amery and West Ice Shelves into the Prydz Bay Gyre. This study highlights the susceptibility of Antarctic bottom water to increased freshwater input from the enhanced melting of ice shelves, and ultimately the potential collapse of Antarctic bottom water formation in a warming climate.
Publisher: Elsevier BV
Date: 03-2004
Publisher: Elsevier BV
Date: 05-2020
Publisher: Inter-Research Science Center
Date: 03-2011
DOI: 10.3354/MEPS08769
Publisher: Public Library of Science (PLoS)
Date: 26-11-2014
Publisher: The Royal Society
Date: 07-01-2013
Abstract: A fundamental goal in animal ecology is to quantify how environmental (and other) factors influence in idual movement, as this is key to understanding responsiveness of populations to future change. However, quantitative interpretation of in idual-based telemetry data is h ered by the complexity of, and error within, these multi-dimensional data. Here, we present an integrative hierarchical Bayesian state-space modelling approach where, for the first time, the mechanistic process model for the movement state of animals directly incorporates both environmental and other behavioural information, and observation and process model parameters are estimated within a single model. When applied to a migratory marine predator, the southern elephant seal ( Mirounga leonina ), we find the switch from directed to resident movement state was associated with colder water temperatures, relatively short e bottom time and rapid descent rates. The approach presented here can have widespread utility for quantifying movement–behaviour ( ing or other)–environment relationships across species and systems.
Publisher: Informa UK Limited
Date: 2002
Publisher: Elsevier BV
Date: 04-2013
Publisher: Cambridge University Press (CUP)
Date: 28-04-2008
DOI: 10.1017/S0007485308005993
Abstract: Mitochondrial ribosomal DNA is commonly used in DNA-based dietary analyses. In such studies, these sequences are generally assumed to be the only version present in DNA of the organism of interest. However, nuclear pseudogenes that display variable similarity to the mitochondrial versions are common in many taxa. The presence of nuclear pseudogenes that co- lify with their mitochondrial paralogues can lead to several possible confounding interpretations when applied to estimating animal diet. Here, we investigate the occurrence of nuclear pseudogenes in fecal s les taken from bottlenose dolphins ( Tursiops truncatus ) that were assayed for prey DNA with a universal primer technique. We found pseudogenes in 13 of 15 s les and 1–5 pseudogene haplotypes per s le representing 5–100% of all licons produced. The proportion of licons that were pseudogenes and the ersity of prey DNA recovered per s le were highly variable and appear to be related to PCR cycling characteristics. This is a well-s led system where we can reliably identify the putative pseudogenes and separate them from their mitochondrial paralogues using a number of recommended means. In many other cases, it would be virtually impossible to determine whether a putative prey sequence is actually a pseudogene derived from either the predator or prey DNA. The implications of this for DNA-based dietary studies, in general, are discussed.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/MF15013
Abstract: Despite being critically endangered, the at-sea behaviour of hawksbill turtles (Eretmochelys imbricata) remains insufficiently understood to support a global conservation strategy. Habitat location and spatial use are poorly documented, which is particularly true for the globally important Australian hawksbill population. We equipped 10 adult female hawksbill turtles nesting on Groote Eylandt, northern Australia, with Fastloc GPS and Argos satellite transmitters. We quantified fine-scale habitat use and area-restricted search behaviour, and located potential feeding and developmental habitats by simulating hatchling turtle dispersal patterns by using a particle-tracking hydrological model. During the breeding season, females mostly remained near their nesting site. Post-breeding, all turtles migrated to foraging sites on the Australian continental shelf, primarily in the Gulf of Carpentaria in coastal seagrass pastures, but also offshore near coral-reef platforms. The distribution of adult foraging grounds was similar to simulated dispersal patterns of hatchling turtles from distant rookeries, thus highlighting the ecological significance of the Gulf of Carpentaria for hawksbill turtles. Although this hawksbill turtle population is likely to be endemic to Australian waters, national and international conservation initiatives are required to mitigate sources of anthropogenic mortality (e.g. illegal tortoise-shell trade, incidental captures in fishing gear, marine debris, seabed mining exploitation).
Publisher: American Geophysical Union (AGU)
Date: 25-09-2018
DOI: 10.1029/2018GL079614
Abstract: The location of the Antarctic Polar Front (PF) is mapped in the Southern Indian Ocean by decomposing the shape of temperature and salinity profiles into vertical modes using a functional Principal Component Analysis. We define the PF as the northernmost minimum of temperature at the subsurface and represent it as a linear combination of the first three modes. This method is applied on an ocean reanalysis data set and on in situ observations, revealing a seasonal variability of the PF latitudinal position that is most pronounced between the Conrad Rise and the Kerguelen Plateau. This shift coincides with variations in the transport across the Northern Kerguelen Plateau. We suggest that seasonal changes of the upper stratification may drive the observed variability of the PF, with potentially large implications for the pathways and residence time of water masses over the plateau and the phytoplankton bloom extending southeast of the Kerguelen Islands.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/ZO17036
Abstract: Southern elephant seals typically breed on subantarctic islands and breeding in more temperate regions is rare. This small female (~1.42 m) that weaned after 25 days is smaller than the average weaned female elephant seal and her survival prospects are correspondingly low (20–35%). The fact that the elephant seal was successfully weaned offers some insight into the breeding plasticity in this species.
Publisher: Elsevier BV
Date: 12-2004
Publisher: Springer Science and Business Media LLC
Date: 12-12-2019
DOI: 10.1038/S41598-019-55152-4
Abstract: Mesopelagic fish and squid occupy ocean depths extending below the photic zone and their vertical migrations represent a massive pathway moving energy and carbon through the water column. Their spatio-temporal distribution is however, difficult to map across remote regions particularly the vast Southern Ocean. This represents a key gap in understanding biogeochemical processes, marine ecosystem structure, and how changing ocean conditions will affect marine predators, which depend upon mesopelagic prey. We infer mesopelagic prey vertical distribution and relative abundance in the Indian sector of the Southern Ocean (20° to 130°E) with a novel approach using predator-derived indices. Fourteen years of southern elephant seal tracking and e data, from the open ocean between the Antarctic Polar Front and the southern Antarctic Circumpolar Current front, clearly show that the vertical distribution of mesopelagic prey is influenced by the physical hydrographic processes that structure their habitat. Mesopelagic prey have a more restricted vertical migration and higher relative abundance closer to the surface where Circumpolar Deep Water rises to shallower depths. Combining these observations with a future projection of Southern Ocean conditions we show that changes in the coupling of surface and deep waters will potentially redistribute mesopelagic prey. These changes are small overall, but show important spatial variability: prey will increase in relative abundance to the east of the Kerguelen Plateau but decrease to the west. The consequences for deep- ing specialists such as elephant seals and whales over this time scale will likely be minor, but the changes in mesoscale vertical energy flow have implications for predators that forage within the mesopelagic zone as well as the broader pelagic ecosystem.
Publisher: Elsevier BV
Date: 06-2008
Publisher: Inter-Research Science Center
Date: 21-04-2008
DOI: 10.3354/MEPS07305
Publisher: Public Library of Science (PLoS)
Date: 29-03-2018
Publisher: Oxford University Press (OUP)
Date: 2015
Publisher: Inter-Research Science Center
Date: 05-05-2008
DOI: 10.3354/MEPS07307
Publisher: Elsevier BV
Date: 07-2022
DOI: 10.1016/J.AUCC.2022.07.006
Abstract: The objective of this study was to describe current surveillance platforms which support routine quality measurement in paediatric critical care. Scoping review. The search strategy consisted of a traditional database and grey literature search as well as expert consultation. Surveillance platforms were eligible for inclusion if they collected measures of quality in critically ill children. The search strategy identified 21 surveillance platforms, collecting 57 unique outcome (70%), process (23%), and structural (7%) quality measures. Hospital-associated infections were the most commonly collected outcome measure across all platforms (n = 11 52%). In general, case definitions were not harmonised across platforms, with the exception of nationally mandated hospital-associated infections (e.g., central line-associated blood stream infection). Data collection relied on manual coding. Platforms typically did not provide an evidence-based rationale for measures collected, with no identifiable reports of co-designed, consensus-derived measures or consumer involvement in measure selection or prioritisation. Quality measurement in critically ill children lacks uniformity in definition which limits local and international benchmarking. Current surveillance activities for critically ill children focus heavily on outcome measurement, with process, structural, and patient-reported measures largely overlooked. Long-term outcome measures were not routinely collected. Harmonisation of paediatric intensive care unit quality measures is needed and can be achieved using prioritisation and consensus/co-design methods.
Publisher: Springer Science and Business Media LLC
Date: 24-02-2020
Publisher: Cambridge University Press (CUP)
Date: 02-2012
DOI: 10.7120/096272812799129493
Abstract: Field-based animal researchers need to balance the potential adverse effects of their research activities against the benefits of research outcomes, but the data required to do this are often lacking. Assessing, and subsequently reporting the effects of researcher activities on wild animal populations can be difficult, so that studies to detect these effects sometimes lack rigour or fail to encompass sufficient time to ensure that the effects are tested under a range of environmental stresses. We monitored the effect of investigators working in colonies of two seabirds, the short-tailed shearwater (Puffinus tenuirostris) and the little penguin (Eudyptula minor) . Disturbance of breeding birds while checking nests or the weighing of chicks to monitor growth are very common activities for demographic and ecological studies, but how these activities may influence the birds is rarely measured. We investigated differing levels of disturbance during both activities between 2002-03 and 2008-09 to assess their effect on egg laying, chick survival and growth rate and observed no effect for nest checking or handling of short-tailed shearwaters and indeterminate effects for handling in little penguins. Over a period of several years the study has observed a large-scale decline in the number of breeding shearwaters and includes years when control nests had above and below average breeding success.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/WR12014
Abstract: Wildlife researchers and conservation biologists are encountering growing research difficulties due to strong and effective advocacy of animal welfare concerns. However, collecting information on the basic biology of animals, which is often essential to effective conservation and management, frequently involves invasive research. The latter is unacceptable to some animal welfare advocates, even if it ultimately leads to better conservation outcomes. For effective bio ersity conservation it is imperative that conservation and wildlife researchers lucidly present the case for their research on in idual animals. This requires conservation biologists and the research community in general, to present these arguments in the public domain as well as in peer-reviewed literature. Moreover, it is important to measure how these activities affect animals. Only then can we show that high quality research activities often have little or no effects on animal vital rates and performance.
Publisher: Springer Science and Business Media LLC
Date: 18-03-2020
DOI: 10.1038/S41597-020-0406-X
Abstract: The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Bio ersity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for multiple species of Antarctic meso- and top-predators to identify Areas of Ecological Significance. These datasets and accompanying syntheses provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, support modelling of predator distributions under future climate scenarios and create inputs that can be incorporated into decision making processes by management authorities. In this data paper, we present the compiled tracking data from research groups that have worked in the Antarctic since the 1990s. The data are publicly available through bio ersity.aq and the Ocean Biogeographic Information System. The archive includes tracking data from over 70 contributors across 12 national Antarctic programs, and includes data from 17 predator species, 4060 in idual animals, and over 2.9 million observed locations.
Publisher: Springer Science and Business Media LLC
Date: 04-10-2019
DOI: 10.1186/S40317-019-0182-6
Abstract: Pinnipeds spend large portions of their lives at sea, submerged, or hauled-out on land, often on remote off-shore islands. This fundamentally limits access by researchers to critical parts of pinniped life history and has spurred the development and implementation of a variety of externally attached telemetry devices (ETDs) to collect information about movement patterns, physiology and ecology of marine animals when they cannot be directly observed. ETDs are less invasive and easier to apply than implanted internal devices, making them more widely used. However, ETDs have limited retention times and their use may result in negative short- and long-term consequences including capture myopathy, impacts to energetics, behavior, and entanglement risk. We identify 15 best practice recommendations for the use of ETDs with pinnipeds that address experimental justification, animal capture, tag design, tag attachment, effects assessments, preparation, and reporting. Continued improvement of best practices is critical within the framework of the Three Rs (Reduction, Refinement, Replacement) these best practice recommendations provide current guidance to mitigate known potential negative outcomes for in iduals and local populations. These recommendations were developed specifically for pinnipeds however, they may also be applicable to studies of other marine taxa. We conclude with four desired future directions for the use of ETDs in technology development, validation studies, experimental designs and data sharing.
Publisher: Wiley
Date: 31-01-2017
DOI: 10.1111/MMS.12392
Publisher: JMIR Publications Inc.
Date: 30-10-2023
DOI: 10.2196/51474
Publisher: Frontiers Media SA
Date: 26-06-2019
Publisher: Wiley
Date: 04-2021
Abstract: Bio‐logging data obtained by tagging animals are key to addressing global conservation challenges. However, the many thousands of existing bio‐logging datasets are not easily discoverable, universally comparable, nor readily accessible through existing repositories and across platforms, slowing down ecological research and effective management. A set of universal standards is needed to ensure discoverability, interoperability and effective translation of bio‐logging data into research and management recommendations. We propose a standardisation framework adhering to existing data principles (FAIR: Findable, Accessible, Interoperable and Reusable and TRUST: Transparency, Responsibility, User focus, Sustainability and Technology) and involving the use of simple templates to create a data flow from manufacturers and researchers to compliant repositories, where automated procedures should be in place to prepare data availability into four standardised levels: (a) decoded raw data, (b) curated data, (c) interpolated data and (d) gridded data. Our framework allows for integration of simple tabular arrays (e.g. csv files) and creation of sharable and interoperable network Common Data Form (netCDF) files containing all the needed information for accuracy‐of‐use, rightful attribution (ensuring data providers keep ownership through the entire process) and data preservation security. We show the standardisation benefits for all stakeholders involved, and illustrate the application of our framework by focusing on marine animals and by providing ex les of the workflow across all data levels, including filled templates and code to process data between levels, as well as templates to prepare netCDF files ready for sharing. Adoption of our framework will facilitate collection of Essential Ocean Variables (EOVs) in support of the Global Ocean Observing System (GOOS) and inter‐governmental assessments (e.g. the World Ocean Assessment), and will provide a starting point for broader efforts to establish interoperable bio‐logging data formats across all fields in animal ecology.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.SCITOTENV.2015.01.089
Abstract: The presence and movements of organisms both reflect and influence the distribution of ecological resources in space and time. The monitoring of animal movement by telemetry devices is being increasingly used to inform management of marine, freshwater and terrestrial ecosystems. Here, we brought together academics, and environmental managers to determine the extent of animal movement research in the Australasian region, and assess the opportunities and challenges in the sharing and reuse of these data. This working group was formed under the Australian Centre for Ecological Analysis and Synthesis (ACEAS), whose overall aim was to facilitate trans-organisational and transdisciplinary synthesis. We discovered that between 2000 and 2012 at least 501 peer-reviewed scientific papers were published that report animal location data collected by telemetry devices from within the Australasian region. Collectively, this involved the capture and electronic tagging of 12 656 animals. The majority of studies were undertaken to address specific management questions rarely were these data used beyond their original intent. We estimate that approximately half (~500) of all animal telemetry projects undertaken remained unpublished, a similar proportion were not discoverable via online resources, and less than 8.8% of all animals tagged and tracked had their data stored in a discoverable and accessible manner. Animal telemetry data contain a wealth of information about how animals and species interact with each other and the landscapes they inhabit. These data are expensive and difficult to collect and can reduce survivorship of the tagged in iduals, which implies an ethical obligation to make the data available to the scientific community. This is the first study to quantify the gap between telemetry devices placed on animals and findings/data published, and presents methods for improvement. Instigation of these strategies will enhance the cost-effectiveness of the research and maximise its impact on the management of natural resources.
Publisher: The Royal Society
Date: 03-2017
DOI: 10.1098/RSOS.160290
Abstract: Cetacean energy stores are known to vary according to life history, reproductive status and time of year however, the opportunity to quantify these relationships is rare. Using a unique set of historical whaling records from Western Australia (1952–1963), we investigated energy stores of large cetaceans with differing life histories, and quantified the relationship between total body lipid and length for humpback whales ( Megaptera novaeangliae) ( n = 905) and sperm whales (Physeter macrocephalus) ( n = 1961). We found that total body lipid increased with body length in both humpback and sperm whales, consistent with size-related energy stores. Male humpback whales stored 2.49 kl (15.6 barrels) (31.9–74.9%) more lipid than male sperm whales of equivalent length, to fuel their annual migration. Relative lipid stores of sperm whales (males) were constant throughout the year, while those of humpback whales varied with reproductive class and s ling date. Pregnant female humpback whales had higher relative energy stores than non-pregnant females and males (26.2% and 37.4%, respectively), to fuel the energy demands of gestation and lactation. Those that reached the s ling site later ( en route to their breeding grounds) carried higher lipid stores than those that arrived earlier, possibly reflecting in idual variation in residency times in the Antarctic feeding grounds. Importantly, longer pregnant females had relatively larger energy stores than the shorter pregnant females, indicating that the smaller in iduals may experience higher levels of energetic stress during the migration fast. The relationships we developed between body lipid and length can be used to inform bioenergetics and ecosystem models when such detailed information is not available.
Publisher: MDPI AG
Date: 23-07-2019
DOI: 10.3390/APP9142935
Abstract: The analysis of animal movement from telemetry data provides insights into how and why animals move. While traditional approaches to such analysis mostly focus on predicting animal states during movement, we describe an approach that allows us to identify representative movement patterns of different animal groups. To do this, we propose a carefully designed recurrent neural network and combine it with telemetry data for automatic feature extraction and identification of non-predefined representative patterns. In the experiment, we consider a particular marine predator species, the southern elephant seal, as an ex le. With our approach, we identify that the male seals in our data set share similar movement patterns when they are close to land. We identify this pattern recurring in a number of distant locations, consistent with alternative approaches from previous research.
Publisher: Springer Science and Business Media LLC
Date: 02-09-2014
Abstract: The instrumentation of southern elephant seals with satellite-linked CTD tags has offered unique temporal and spatial coverage of the Southern Indian Ocean since 2004. This includes extensive data from the Antarctic continental slope and shelf regions during the winter months, which is outside the conventional areas of Argo autonomous floats and ship-based studies. This landmark dataset of around 75,000 temperature and salinity profiles from 20–140 °E, concentrated on the sector between the Kerguelen Islands and Prydz Bay, continues to grow through the coordinated efforts of French and Australian marine research teams. The seal data are quality controlled and calibrated using delayed-mode techniques involving comparisons with other existing profiles as well as cross-comparisons similar to established protocols within the Argo community, with a resulting accuracy of ±0.03 °C in temperature and ±0.05 in salinity or better. The data offer invaluable new insights into the water masses, oceanographic processes and provides a vital tool for oceanographers seeking to advance our understanding of this key component of the global ocean climate.
Publisher: Springer Science and Business Media LLC
Date: 05-01-2010
DOI: 10.1007/S00359-009-0501-0
Abstract: Physiological stress responses to capture may be an indicator of welfare challenges induced by animal handling. Simultaneously, blood chemistry changes induced by stress responses may confound experimental design by interacting with the biological parameters being measured. Cortisol elevation is a common indicator of stress responses in mammals and reproductive condition can profoundly influence endocrine response. We measured changes in blood cortisol and testosterone induced by handling reproductively active male Weddell seals (Leptonychotes weddellii) early and late in the breeding season. Weddell seals have the highest resting cortisol levels of all mammals yet showed a clear, prolonged elevation in cortisol in response to capture. Responses were similar when first caught and when caught a second time, later in the breeding season. Baseline testosterone levels declined over the breeding season but were not altered by capture. Administering a light dose of diazepam significantly ameliorated the cortisol response of handled animals without affecting testosterone levels. This may be an effective way of reducing acute capture stress responses. Male breeding success in years males were handled was no different to the years they were not, despite the acute capture response, suggesting no long-term impact of handling on male reproductive output.
Publisher: Springer Science and Business Media LLC
Date: 08-09-2005
DOI: 10.1007/S00442-004-1704-2
Abstract: In highly dynamic and unpredictable environments such as the Southern Ocean, species that have evolved behaviors that reduce the effects of intra-specific competition may have a selective advantage. This is particularly true when juveniles face disadvantages when foraging due to morphological or physiological limitation, which is the case for many marine mammals. We tracked the at-sea movements of 48 juvenile southern elephant seals ( Mirounga leonina) between the ages of 1 and 4 years from the population at Macquarie Island using locations derived from recorded light levels. There were significant differences in the total amount of the Southern Ocean covered by the different age-groups. The younger seals used a smaller area than the older seals. On average, the younger in iduals also made more trips to sea than the older seals and did not travel as far on each trip. Females spent more time at sea than males and there were no significant differences between the total areas used by male and females. In summary, younger seals remained closer to the island at all times, and they spent more time in more northerly regions that older seals. These differences in behavior created temporal and spatial segregation between juveniles of different ages. Therefore, we suggest that these temporal and spatial separations help to avoid intra-specific competition for resources on land, space on beaches, and at-sea foraging areas. Such modifications of haul-out timing and behavior enable them to exploit a patchy and unpredictable environment.
Publisher: Inter-Research Science Center
Date: 26-09-2019
DOI: 10.3354/MEPS13095
Publisher: Elsevier BV
Date: 02-2003
Publisher: Wiley
Date: 04-09-2011
Publisher: Wiley
Date: 05-09-2007
Publisher: Frontiers Media SA
Date: 14-12-2018
Publisher: Inter-Research Science Center
Date: 13-10-2017
DOI: 10.3354/MEPS12312
Publisher: University of Chicago Press
Date: 09-2008
DOI: 10.1086/590397
Abstract: A major source of energy during lactation in mammals is provided through the mobilization of blubber fatty acids (FAs). We investigated the extent to which FAs were mobilized to support both maternal metabolic requirements and milk production in the Weddell seal and how this was reflected in the FA composition of the pup's blubber at the end of lactation (EL). FA composition of postpartum female blubber was similar in the 2 yr of study (2002 and 2003) but differed markedly by EL. Pup blubber FAs (at EL) were also different between years and did not match that of the mother's milk or blubber. Milk FA composition changed during lactation, which may have been a reflection of an increase in pup energy demands at different stages of development. In addition, there was evidence of feeding by some females during lactation, with higher levels of some FAs in the milk than in the blubber. Our results indicate that differential mobilization of FAs occurred in lactating Weddell seals and that this was related to total body lipid stores at postpartum. Furthermore, growing pups did not store FAs unmodified, providing evidence that selective use does occur and also that using FA composition to elucidate dietary sources may be problematic in growing in iduals.
Publisher: Elsevier BV
Date: 05-2001
Publisher: Elsevier BV
Date: 2014
Publisher: Wiley
Date: 07-2009
Publisher: Springer Science and Business Media LLC
Date: 09-02-2006
Abstract: Chemical immobilization of Weddell seals ( Leptonychotes weddellii ) has previously been, for the most part, problematic and this has been mainly attributed to the type of immobilizing agent used. In addition to in idual sensitivity, physiological status may play an important role. We investigated the use of the intravenous administration of a 1:1 mixture of tiletamine and zolazepam (Telazol ® ) to immobilize adult females at different points during a physiologically demanding 5–6 week lactation period. We also compared performance between IV and IM injection of the same mixture. The tiletamine:zolazepam mixture administered intravenously was an effective method for immobilization with no fatalities or pronounced apnoeas in 106 procedures however, there was a 25 % (one animal in four) mortality rate with intramuscular administration. Induction time was slightly longer for females at the end of lactation (54.9 ± 2.3 seconds) than at post-parturition (48.2 ± 2.9 seconds). In addition, the number of previous captures had a positive effect on induction time. There was no evidence for effects due to age, condition (total body lipid), stage of lactation or number of captures on recovery time. We suggest that intravenous administration of tiletamine and zolazepam is an effective and safe immobilizing agent for female Weddell seals. Although in idual traits could not explain variation in recovery time, we suggest careful monitoring of recovery times during longitudinal studies ( 2 captures). We show that physiological pressures do not substantially affect response to chemical immobilization with this mixture however, consideration must be taken for differences that may exist for immobilization of adult males and juveniles. Nevertheless, we recommend a mass-specific dose of 0.50 – 0.65 mg/kg for future procedures with adult female Weddell seals and a starting dose of 0.50 mg/kg for other age classes and other phocid seals.
Publisher: Inter-Research Science Center
Date: 14-05-2007
DOI: 10.3354/MEPS337265
Publisher: Wiley
Date: 07-08-2013
DOI: 10.1111/J.1365-2656.2012.02021.X
Abstract: Many optimal foraging models for ing animals examine strategies that maximize time spent in the foraging zone, assuming that prey acquisition increases linearly with search time. Other models have considered the effect of patch quality and predict a net energetic benefit if es where no prey is encountered early in the e are abandoned. For deep ers, however, the energetic benefit of giving up is reduced owing to the elevated energy costs associated with descending to physiologically hostile depths, so patch residence time should be invariant. Others consider an asymptotic gain function where the decision to leave a patch is driven by patch-depletion effects - the marginal value theorem. As predator behaviour is increasingly being used as an index of marine resource density and distribution, it is important to understand the nature of this gain function. We investigated the e behaviour of the world's deepest- ing seal, the southern elephant seal Mirounga leonina, in response to patch quality. Testing these models has largely been limited to controlled experiments on captive animals. By integrating in situ measurements of the seal's relative lipid content obtained from drift rate data (a measure of foraging success) with area-restricted search behaviour identified from first-passage time analysis, we identified regions of high- and low-quality patches. Dive durations and bottom times were not invariant and did not increase in regions of high quality rather, both were longer when patches were of relatively low quality. This is consistent with the predictions of the marginal value theorem and provides support for a nonlinear relationship between search time and prey acquisition. We also found higher descent and ascent rates in high-quality patches suggesting that seals minimized travel time to the foraging patch when quality was high however, this was not achieved by increasing speed or e angle. Relative body lipid content was an important predictor of e behaviour. Seals did not schedule their ing to maximize time spent in the foraging zone in higher-quality patches, challenging the widely held view that maximizing time in the foraging zone translates to greater foraging success.
Publisher: Inter-Research Science Center
Date: 16-02-2007
DOI: 10.3354/MEPS331281
Publisher: Elsevier BV
Date: 09-2017
Publisher: Springer Science and Business Media LLC
Date: 24-02-2017
DOI: 10.1038/SREP43236
Abstract: Contrasting regional changes in Southern Ocean sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. Quantifying how Antarctic predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. Over an 11-year time-series, we examine how inter-annual variability in sea ice concentration and advance affect the foraging behaviour of a top Antarctic predator, the southern elephant seal. Females foraged longer in pack ice in years with greatest sea ice concentration and earliest sea ice advance, while males foraged longer in polynyas in years of lowest sea ice concentration. There was a positive relationship between near-surface meridional wind anomalies and female foraging effort, but not for males. This study reveals the complexities of foraging responses to climate forcing by a poleward migratory predator through varying sea ice property and dynamic anomalies.
Publisher: The Royal Society
Date: 03-2023
DOI: 10.1098/RSOS.221635
Abstract: Developmental differences in vital rates are especially profound in polygamous mating systems. Southern elephant seals ( Mirounga leonina ) are highly dimorphic and extremely polygynous marine mammals. A demographic model, supported by long-term capture–mark–recapture records, investigated the influence of sex and age on survival in this species. The study revealed clear differences between female and male age-dependent survival rates. Overall juvenile survival estimates were stable around 80–85% for both sexes. However, male survival estimates were 5–10% lower than females in the same age classes until 8 years of age. At this point, male survival decreased rapidly to 50% ± 10% while female estimates remained constant at 80% ± 5%. Different energetic requirements could underpin intersex differences in adult survival. However, the species' strong sexual dimorphism erges during early juvenile development when sex-specific survival rates were less distinct. Maximizing growth is especially advantageous for males, with size being a major determinant of breeding probability. Maturing males may employ a high-risk high-reward foraging strategy to compensate for extensive sexual selection pressures and sex-specific energetic needs. Our findings suggest sex-specific adult survival is a result of in situ ecological interactions and evolutionary specialization associated with being a highly polygynous marine predator.
Publisher: Wiley
Date: 12-06-2012
DOI: 10.1002/ECE3.281
Publisher: Public Library of Science (PLoS)
Date: 13-10-2009
Publisher: Wiley
Date: 27-09-2018
DOI: 10.1111/ECOG.03080
Publisher: Springer Science and Business Media LLC
Date: 22-07-2004
Publisher: Wiley
Date: 02-2015
DOI: 10.1890/14-0469.1
Abstract: In animal ecology, a question of key interest for aquatic species is how changes in movement behavior are related in the horizontal and vertical dimensions when in iduals forage. Alternative theoretical models and inconsistent empirical findings mean that this question remains unresolved. Here we tested expectations by incorporating the vertical dimension ( e information) when predicting switching between movement states ("resident" or "directed") within a state-space model. We integrated telemetry-based tracking and ing data available for four seal species (southern elephant, Weddell, antarctic fur, and crabeater) in East Antarctica. Where possible, we included e variables derived from the relationships between (1) e duration and depth (as a measure of effort), and (2) e duration and the post e surface interval (as a physiological measure of cost). Our results varied within and across species, but there was a general tendency for the probability of switching into "resident" state to be positively associated with shorter e durations (for a given depth) and longer post e surface intervals (for a given e duration). Our results add to a growing body of literature suggesting that simplistic interpretations of optimal foraging theory based only on horizontal movements do not directly translate into the vertical dimension in dynamic marine environments. Analyses that incorporate at least two dimensions can test more sophisticated models of foraging behavior.
Publisher: The Royal Society
Date: 05-2014
Abstract: When to commence breeding is a crucial life-history decision that may be the most important determinant of an in idual's lifetime reproductive output and can have major consequences on population dynamics. The age at which in iduals first reproduce is an important factor influencing the intensity of potential costs (e.g. reduced survival) involved in the first breeding event. However, quantifying age-related variation in the cost of first reproduction in wild animals remains challenging because of the difficulty in reliably recording the first breeding event. Here, using a multi-event capture–recapture model that accounts for both imperfect detection and uncertainty in the breeding status on an 18-year dataset involving 6637 in iduals, we estimated age and state-specific survival of female elephant seals ( Mirounga leonina ) in the declining Macquarie Island population. We detected a clear cost of first reproduction on survival. This cost was higher for both younger first-time breeders and older first-time breeders compared with females recruiting at age four, the overall mean age at first reproduction. Neither earlier primiparity nor delaying primiparity appear to confer any evolutionary advantage, rather the optimal strategy seems to be to start breeding at a single age, 4 years.
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.MARPOLBUL.2019.04.021
Abstract: Pollution of the world's oceans by marine debris has direct consequences for wildlife, with fragments of plastic <10 mm the most abundant buoyant litter in the ocean. Seabirds are susceptible to debris ingestion, commonly mistaking floating plastics for food. Studies have shown that half of petrel species regularly ingest anthropogenic waste. Despite the regularity of debris ingestion, no studies to date have quantified the dimensions of debris items ingested across petrel species ranging in size. We excised and measured 1694 rigid anthropogenic debris items from 348 petrel carcasses of 20 species. We found that although the size of items ingested by petrels scale positively with the size of the bird, 90% of all debris items ingested across species fall within a narrow "danger zone" range of 2-10 mm, overlapping with the most abundant oceanic debris size. We conclude that this globally profuse size range of marine plastics is an ingestion hazard to petrels.
Publisher: Cambridge University Press (CUP)
Date: 09-2002
DOI: 10.1017/S0954102002000020
Abstract: The water and calorific content of fifteen species of mesopelagic sub-Antarctic fish from Macquarie Island were determined. Mean percent water content was 69–82%. Calorific content was highly variable between species, especially in the Myctophidae, where it ranged between 22.6–59.3 kJ·g −1 dry weight. The water and calorific content varied with size class within a species, with the smallest size classes generally having the lowest water content but highest calorific content. These values will be useful for future assessment of energetic transfer between trophic levels and energetic modelling of Southern Ocean ecosystems.
Publisher: Proceedings of the National Academy of Sciences
Date: 27-02-2023
Abstract: Assessing environmental changes in Southern Ocean ecosystems is difficult due to its remoteness and data sparsity. Monitoring marine predators that respond rapidly to environmental variation may enable us to track anthropogenic effects on ecosystems. Yet, many long-term datasets of marine predators are incomplete because they are spatially constrained and/or track ecosystems already modified by industrial fishing and whaling in the latter half of the 20th century. Here, we assess the contemporary offshore distribution of a wide-ranging marine predator, the southern right whale (SRW, Eubalaena australis ), that forages on copepods and krill from ~30°S to the Antarctic ice edge ( °S). We analyzed carbon and nitrogen isotope values of 1,002 skin s les from six genetically distinct SRW populations using a customized assignment approach that accounts for temporal and spatial variation in the Southern Ocean phytoplankton isoscape. Over the past three decades, SRWs increased their use of mid-latitude foraging grounds in the south Atlantic and southwest (SW) Indian oceans in the late austral summer and autumn and slightly increased their use of high-latitude ( °S) foraging grounds in the SW Pacific, coincident with observed changes in prey distribution and abundance on a circumpolar scale. Comparing foraging assignments with whaling records since the 18th century showed remarkable stability in use of mid-latitude foraging areas. We attribute this consistency across four centuries to the physical stability of ocean fronts and resulting productivity in mid-latitude ecosystems of the Southern Ocean compared with polar regions that may be more influenced by recent climate change.
Publisher: Wiley
Date: 26-12-2017
Publisher: Public Library of Science (PLoS)
Date: 04-06-2010
Publisher: Inter-Research Science Center
Date: 13-10-2008
DOI: 10.3354/MEPS07633
Publisher: Wiley
Date: 25-10-2013
DOI: 10.1002/ECE3.846
Publisher: Elsevier BV
Date: 2014
Publisher: Public Library of Science (PLoS)
Date: 06-06-2017
Publisher: Springer Science and Business Media LLC
Date: 02-08-2015
DOI: 10.1007/S00442-015-3407-2
Abstract: Estimating the degree of in idual specialisation is likely to be sensitive to the methods used, as they record in iduals' resource use over different time-periods. We combined animal-borne video cameras, GPS/TDR loggers and stable isotope values of plasma, red cells and sub-s led whiskers to investigate in idual foraging specialisation in female Australian fur seals (Arctocephalus pusillus doriferus) over various timescales. Combining these methods enabled us to (1) provide quantitative information on in iduals' diet, allowing the identification of prey, (2) infer the temporal consistency of in idual specialisation, and (3) assess how different methods and timescales affect our estimation of the degree of specialisation. Short-term inter-in idual variation in diet was observed in the video data (mean pairwise overlap = 0.60), with the s led population being composed of both generalist and specialist in iduals (nested network). However, the brevity of the temporal window is likely to artificially increase the level of specialisation by not recording the entire diet of seals. Indeed, the correlation in isotopic values was tighter between the red cells and whiskers (mid- to long-term foraging ecology) than between plasma and red cells (short- to mid-term) (R(2) = 0.93-0.73 vs. 0.55-0.41). δ(13)C and δ(15)N values of whiskers confirmed the temporal consistency of in idual specialisation. Variation in isotopic niche was consistent across seasons and years, indicating long-term habitat (WIC/TNW = 0.28) and dietary (WIC/TNW = 0.39) specialisation. The results also highlight time-averaging issues (under-estimation of the degree of specialisation) when calculating in idual specialisation indices over long time-periods, so that no single timescale may provide a complete and accurate picture, emphasising the benefits of using complementary methods.
Publisher: Wiley
Date: 11-05-2007
Publisher: Elsevier BV
Date: 06-2017
Publisher: The Royal Society
Date: 26-01-2022
Abstract: Antarctic polynyas are persistent open water areas which enable early and large seasonal phytoplankton blooms. This high primary productivity, boosted by iron supply from coastal glaciers, attracts organisms from all trophic levels to form a rich and erse community. How the ecological benefit of polynya productivity is translated to the highest trophic levels remains poorly resolved. We studied 119 southern elephant seals feeding over the Antarctic shelf and demonstrated that: (i) 96% of seals foraging here used polynyas, with in iduals spending on average 62% of their time there (ii) the seals exhibited more area-restricted search behaviour when in polynyas and (iii) these seals gained more energy (indicated by increased buoyancy from greater fat stores) when inside polynyas. This higher-quality foraging existed even when ice was not present in the study area, indicating that these are important and predictable foraging grounds year-round. Despite these energetic advantages from using polynyas, not all the seals used them extensively. Factors other than food supply may influence an in idual's choice in their use of feeding grounds, such as exposure to predation or the probability of being able to return to distant sub-Antarctic breeding sites.
Publisher: Springer Science and Business Media LLC
Date: 06-11-2008
DOI: 10.1007/S00442-008-1205-9
Abstract: Assessing the status and trends in animal populations is essential for effective species conservation and management practices. However, unless time-series abundance data demonstrate rapid and reliable fluctuations, objective appraisal of directionality of trends is problematic. We adopted a multiple-working hypotheses approach based on information-theoretic and Bayesian multi-model inference to examine the population trends and form of intrinsic regulation demonstrated by a long-lived species, the southern elephant seal. We also determined the evidence for density dependence in 11 other well-studied marine mammal species. (1) We tested the type of population regulation for elephant seals from Marion Island (1986-2004) and from 11 other marine mammal species, and (2) we described the trends and behavior of the 19-year population time series at Marion Island to identify changes in population trends. We contrasted five plausible trend models using information-theoretic and Bayesian-inference estimates of model parsimony. Our analyses identified two distinct phases of population growth for this population with the inflexion occurring in 1998. Thus, the population decreased between 1986 and 1997 (-3.7% per annum) and increased between 1997 and 2004 (1.9% per annum). An index of environmental stochasticity, the Southern Oscillation Index, explained some of the variance in r and N. We determined analytically that there was good evidence for density dependence in the Marion Island population and that density dependence was widespread among marine mammal species (67% of species showed evidence for population regulation). This approach demonstrates the potential functionality of a relatively simple technique that can be applied to short time series to identify the type of regulation, and the uncertainty associated with the phenomenon, operating in populations of large mammals.
Publisher: Springer Science and Business Media LLC
Date: 20-06-2019
DOI: 10.1038/S41598-019-44970-1
Abstract: Foraging behaviour of marine predators inferred from the analysis of horizontal or vertical movements commonly lack quantitative information about foraging success. Several marine mammal species are known to perform es where they passively drift in the water column, termed “drift” es. The drift rate is determined by the animal’s buoyancy, which can be used to make inference regarding body condition. Long term e records retrieved via satellite uplink are often summarized before transmission. This loss of resolution h ers identification of drift es. Here, we develop a flexible, hierarchically structured approach to identify drift es and estimate the drift rate from the summarized time-depth profiles that are increasingly available to the global research community. Based on high-resolution e data from southern elephant seals, we classify es as drift/non-drift and apply a summarization algorithm. We then (i) automatically generate e groups based on inflection point ordering using a ‘Reverse’ Broken-Stick Algorithm, (ii) develop a set of threshold criteria to apply across groups, ensuring non-drift es are most efficiently rejected, and (iii) finally implement a custom Kalman filter to retain the remaining es that are within the seals estimated drifting time series. Validation with independent data sets shows our method retains approximately 3% of all es, of which 88% are true drift es. The drift rate estimates are unbiased, with the upper 95% quantile of the mean squared error between the daily averaged summarized profiles using our method (SDDR) and the observed daily averaged drift rate (ODDR) being only 0.0015. The trend of the drifting time-series match expectations for capital breeders, showing the lowest body condition commencing foraging trips and a progressive improvement as they remain at sea. Our method offers sufficient resolution to track small changes in body condition at a fine temporal scale. This approach overcomes a long-term challenge for large existing and ongoing data collections, with potential application across other drift ing species. Enabling robust identification of foraging success at sea offers a rare and valuable opportunity for monitoring marine ecosystem productivity in space and time by tracking the success of a top predator.
Publisher: Wiley
Date: 09-04-2201
DOI: 10.1111/ECOG.04939
Publisher: Public Library of Science (PLoS)
Date: 12-07-2012
Publisher: Cambridge University Press (CUP)
Date: 06-2002
DOI: 10.1017/S095410200200069X
Abstract: Twenty-three juvenile (8–14 months of age) southern elephant seals ( Mirounga leonina L.) from Macquarie Island were tracked during 1993 and 1995. Migratory tracks and ocean areas with concentrated activity, presumed to be foraging grounds, were established from location data gathered by attached geolocation-time depth recorders. The seals ranged widely (811–3258 km) and foraging activity centred on oceanographic frontal systems, especially the Antarctic Polar Front and bathymetric features such as the C bell Plateau region. The seals spent 58.6% of their sea time within managed fishery areas while the remainder was spent on the high seas, an area of unregulated fishing. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) areas 58.4.1, 88.2 and especially 88.1 were important and distant foraging areas for these juvenile elephant seals. From fisheries records, diet and the foraging ecology studies of the seals there appears to be little, if any, overlap or conflict between the seals and commercial fishing operations within the regulated commercial areas. However, attention is drawn to the possibility of future interactions if Southern Ocean fisheries expand or new ones commence.
Publisher: JMIR Publications Inc.
Date: 02-08-2023
Publisher: Elsevier BV
Date: 04-2003
DOI: 10.1016/S1095-6433(03)00045-X
Abstract: Blubber thickness (n=102) and lipid content (n=37) were measured in sperm whales from three mass stranding events on the west and north-west coasts of Tasmania, Australia in February 1998. Blubber thickness was highly variable, ranging from 43.0 to 168.0 mm (mean 98.4+/-18.4 mm) while lipid fat content, also highly variable, ranged from 16.19 to 89.34% (mean 49.2+/-17.9%). Blubber thickness was significantly and positively related to total length, but a blubber thickness index based on the residuals of this relationship was not related to age, sex or reproductive condition. No relationship was found between blubber thickness index and blubber lipid content, indicating that blubber thickness may not provide a comprehensive indication of body fat condition in sperm whales when only measured at a single site. Blubber lipid content was not related to total length, age or sex. Blubber lipid content was stratified vertically throughout the blubber layer, suggesting that the inner blubber layer may be a more active site for lipid deposition and mobilisation, while the outer blubber layer may serve in a structural or thermoregulatory role. The social structure and foraging ecology of this species may serve to minimise the need to rely on stored energy reserves to meet reproductive energy requirements. In addition, the broader role of blubber for structural, buoyancy and insulative functions coupled with high in idual variability may cause a lack of obvious relationships between these variables and body size, age, sex and reproductive state in this species.
Publisher: Wiley
Date: 19-07-2013
Publisher: Informa UK Limited
Date: 03-04-2018
Publisher: Wiley
Date: 14-10-2008
DOI: 10.1111/J.1365-2656.2008.01437.X
Abstract: 1. Seasonal long-distance migrations are often expected to be related to resource distribution, and foraging theory predicts that animals should spend more time in areas with relatively richer resources. Yet for highly migratory marine species, data on feeding success are difficult to obtain. We analysed the temporal feeding patterns of wild juvenile southern bluefin tuna from visceral warming patterns recorded by archival tags implanted within the body cavity. 2. Data collected during 1998-2000 totalled 6221 days, with in idual time series (n = 19) varying from 141 to 496 days. These data span an annual migration circuit including a coastal summer residency within Australian waters and subsequent migration into the temperate south Indian Ocean. 3. In idual fish recommenced feeding between 5 and 38 days after tagging, and feeding events (n = 5194) were subsequently identified on 76.3 +/- 5.8% of days giving a mean estimated daily intake of 0.75 +/- 0.05 kg. 4. The number of feeding events varied significantly with time of day with the greatest number occurring around dawn (58.2 +/- 8.0%). Night feeding, although rare (5.7 +/- 1.3%), was linked to the full moon quarter. Southern bluefin tuna foraged in ambient water temperatures ranging from 4.9 degrees C to 22.9 degrees C and depths ranging from the surface to 672 m, with different targeting strategies evident between seasons. 5. No clear relationship was found between feeding success and time spent within an area. This was primarily due to high in idual variability, with both positive and negative relationships observed at all spatial scales examined (grid ranges of 2 x 2 degrees to 10 x 10 degrees ). Assuming feeding success is proportional to forage density, our data do not support the hypothesis that these predators concentrate their activity in areas of higher resource availability. 6. Multiple-day fasting periods were recorded by most in iduals. The majority of these (87.8%) occurred during periods of apparent residency within warmer waters (sea surface temperature > 15 degrees C) at the northern edge of the observed migratory range. These previously undocumented nonfeeding periods may indicate alternative motivations for residency. 7. Our results demonstrate the importance of obtaining information on feeding when interpreting habitat utilization from in idual animal tracks.
Publisher: Inter-Research Science Center
Date: 24-03-2017
DOI: 10.3354/MEPS12085
Publisher: Springer Science and Business Media LLC
Date: 03-2019
DOI: 10.1038/S41598-018-36585-9
Abstract: Procellariiformes are the most threatened bird group globally, and the group with the highest frequency of marine debris ingestion. Marine debris ingestion is a globally recognized threat to marine bio ersity, yet the relationship between how much debris a bird ingests and mortality remains poorly understood. Using cause of death data from 1733 seabirds of 51 species, we demonstrate a significant relationship between ingested debris and a debris-ingestion cause of death (dose-response). There is a 20.4% chance of lifetime mortality from ingesting a single debris item, rising to 100% after consuming 93 items. Obstruction of the gastro-intestinal tract is the leading cause of death. Overall, balloons are the highest-risk debris item 32 times more likely to result in death than ingesting hard plastic. These findings have significant implications for quantifying seabird mortality due to debris ingestion, and provide identifiable policy targets aimed to reduce mortality for threatened species worldwide.
Publisher: MDPI AG
Date: 15-04-2021
Abstract: We aimed to explore university students’ perceptions and experiences of SARS-CoV-2 mass asymptomatic testing, social distancing and self-isolation, during the COVID-19 pandemic. This qualitative study comprised of four rapid online focus groups conducted at a higher education institution in England, during high alert (tier 2) national COVID-19 restrictions. Participants were purposively s led university students (n = 25) representing a range of gender, age, living circumstances (on/off c us), and SARS-CoV-2 testing/self-isolation experiences. Data were analysed using an inductive thematic approach. Six themes with 16 sub-themes emerged from the analysis of the qualitative data: ‘Term-time Experiences’, ‘Risk Perception and Worry’, ‘Engagement in Protective Behaviours’, ‘Openness to Testing’, ‘Barriers to Testing’ and ‘General Wellbeing’. Students described feeling safe on c us, believed most of their peers are adherent to protective behaviours and were positive towards asymptomatic testing in university settings. University communications about COVID-19 testing and social behaviours need to be timely and presented in a more inclusive way to reach groups of students who currently feel marginalised. Barriers to engagement with SARS-CoV-2 testing, social distancing and self-isolation were primarily associated with fear of the mental health impacts of self-isolation, including worry about how they will cope, high anxiety, low mood, guilt relating to impact on others and loneliness. Loneliness in students could be mitigated through increased intra-university communications and a focus on establishment of low COVID-risk social activities to help students build and enhance their social support networks. These findings are particularly pertinent in the context of mass asymptomatic testing programmes being implemented in educational settings and high numbers of students being required to self-isolate. Universities need to determine the support needs of students during self-isolation and prepare for the long-term impacts of the pandemic on student mental health and welfare support services.
Publisher: Wiley
Date: 14-01-2011
DOI: 10.1111/J.1755-0998.2010.02976.X
Abstract: Chronological age is a fundamental and yet elusive variable in studies of many wild animals. Telomeres are nucleoprotein structures on the ends of chromosomes that change size throughout the life of many animals and because of this property have been advocated as a means to estimate age. In this review, we assess the existing and potential application of using telomeres for age estimation. We argue that there are conceptual and statistical inconsistencies in previous studies and that the basis for telomere change over time is not well understood and affected by several intrinsic and extrinsic process unrelated to chronological time. Furthermore, these processes are likely to vary spatially and temporally for animal populations. We conclude that the current data suggest telomeres should not be used for age estimation. If telomere-based age estimation is to be used, more work in understanding variability in key processes affecting telomere dynamics and rigorous substantiation via blind testing is needed.
Publisher: Springer Science and Business Media LLC
Date: 22-08-2007
Publisher: The Royal Society
Date: 23-06-2013
Abstract: Diet is a fundamental aspect of animal ecology. Cetacean prey species are generally identified by examining stomach contents of stranded in iduals. Critical uncertainty in these studies is whether s les from stranded animals are representative of the diet of free-ranging animals. Over two summers, we collected faecal and gastric s les from healthy free-ranging in iduals of an extensively studied bottlenose dolphin population. These s les were analysed by molecular prey detection and these data compared with stomach contents data derived from stranded dolphins from the same population collected over 22 years. There was a remarkable consistency in the prey species composition and relative amounts between the two datasets. The conclusions of past stomach contents studies regarding dolphin habitat associations, prey selection and proposed foraging mechanisms are supported by molecular data from live animals and the combined dataset. This is the first explicit test of the validity of stomach contents analysis for accurate population-scale diet determination of an inshore cetacean.
Publisher: Cold Spring Harbor Laboratory
Date: 31-07-2021
DOI: 10.1101/2021.07.29.21261196
Abstract: The impact of changing social restrictions on the mental health of students during the COVID-19 pandemic warrants exploration. To prospectively examine changes to university students’ mental health during the pandemic. Students completed repeated online surveys at three time points (October 2020 (baseline), February 2021, March 2021) to explore relationships between demographic and psychological factors (loneliness and positive mood) and mental health outcomes (depression, anxiety, and stress). A total of 893 students participated. Depression and anxiety levels were higher at all timepoints than pre-pandemic normative data ( p .001). Scores on all mental health measures were highest in February, with depression and anxiety remaining significantly higher in March than baseline. Female students and those with previous mental health disorders were at greatest risk of poor mental health outcomes. Lower positive mood and greater loneliness at baseline were associated with greater depression and anxiety at follow-ups. Baseline positive mood predicted improvement of depression and anxiety at follow-ups. Depression and anxiety were significantly higher than pre-pandemic norms, with female students and those with previous mental health difficulties being at greatest risk. Given these elevated rates, universities should ensure adequate support is available to meet potentially increased demand for services.
Publisher: Springer Science and Business Media LLC
Date: 06-2004
Publisher: Public Library of Science (PLoS)
Date: 05-09-2007
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/WR00066
Abstract: The total body water (TBW) and body condition of 86 female southern elephant seals was estimated from tritiated water (HTO) dilution space analysis. HTO blood s les were analysed using two distillation methods (direct serum counts and evaporative freeze capture) that yielded significantly different estimates. Evaporative freeze capture is recommended for use because it is faster, cheaper, and provides a more precise TBW estimate of dilution space. Estimates of TBW were then compared with those derived from bioelectrical impedance analysis (BIA) and morphometric models. There were significant, positive relationships between TBW and BIA variables, but the level of accuracy was inadequate for BIA to be more useful than the other methods trialled. Morphometric models accurately estimated TBW (kg). Models developed from surface area (SA) (TBW = [SA * 82.58] – 86.94) and from a combination of mass (M), length (L), and girth (G) (TBW = [(M * 0.72) + (L * 5.49) + (G * 134.94) + 164.36)] provided the most accurate TBW estimates. In contrast, condition indices did not give accurate or reliable estimates of relative body condition.
Publisher: University of Chicago Press
Date: 07-2005
DOI: 10.1086/430227
Publisher: Inter-Research Science Center
Date: 28-10-2008
DOI: 10.3354/MEPS07613
Publisher: Public Library of Science (PLoS)
Date: 24-01-2014
Publisher: University of Chicago Press
Date: 11-2000
DOI: 10.1086/318104
Abstract: The ability of air-breathing marine predators to forage successfully depends on their ability to remain submerged. This is in turn related to their total O(2) stores and the rate at which these stores are used up while submerged. Body size was positively related to e duration in a s le of 34 adult female southern elephant seals from Macquarie Island. However, there was no relationship between body size and e depth. This indicates that smaller seals, with smaller total O(2) stores, make shorter es than larger in iduals but operate at similar depths, resulting in less time being spent at depth. Nine adult female elephant seals were also equipped with velocity time depth recorders. In eight of these seals, a plot of swimming speed against e duration revealed a cloud of points with a clear upper boundary. This boundary could be described using regression analysis and gave a significant negative relationship in most cases. These results indicate that metabolic rate varies with activity levels, as indicated by swimming speed, and that there are quantifiable limits to the distance that a seal can travel on a e of a given swimming speed. However, the seals rarely e to these physiological limits, and the majority of their es are well within their aerobic capacity. Elephant seals therefore appear to e in a way that ensures that they have a reserve of O(2) available.
Publisher: PeerJ
Date: 08-08-2018
DOI: 10.7717/PEERJ.5306
Abstract: Over the past five decades, marine mammal interactions with fisheries have become a major human-wildlife conflict globally. The emergence of longline fishing is concomitant with the development of depredation-type interactions i.e., marine mammals feeding on fish caught on hooks. The killer whale ( Orcinus orca ) is one of the species most involved in depredation on longline fisheries. The issue was first reported in high latitudes but, with increasing expansion of this fishing method, other fisheries have begun to experience interactions. The present study investigated killer whale interactions with two geographically isolated blue-eye trevalla ( Hyperoglyphe antarctica ) fisheries operating in temperate waters off Amsterdam/St. Paul Islands (Indian Ocean) and south-eastern Australia. These two fisheries differ in the fishing technique used (vertical vs. demersal longlines), effort, catch, fleet size and fishing area size. Using 7-year (2010–16) long fishing and observation datasets, this study estimated the levels of killer whale interactions and examined the influence of spatio-temporal and operational variables on the probability of vessels to experience interactions. Killer whales interactions occurred during 58.4% and 21.2% of all fishing days, and over 94% and 47.4% of the fishing area for both fisheries, respectively. In south-eastern Australia, the probability of occurrence of killer whale interactions during fishing days varied seasonally with a decrease in spring, increased with the daily fishing effort and decreased with the distance travelled by the vessel between fishing days. In Amsterdam/St. Paul, this probability was only influenced by latitude, with an increase in the southern part of the area. Together, these findings document two previously unreported cases of high killer whale depredation, and provide insights on ways to avoid the issue. The study also emphasizes the need to further examine the local characteristics of fisheries and the ecology of local depredating killer whale populations in as important drivers of depredation.
Publisher: Wiley
Date: 29-01-2021
DOI: 10.1002/ECE3.7147
Publisher: Wiley
Date: 24-12-2018
DOI: 10.1002/ECY.2566
Abstract: Like many species, movement patterns of southern elephant seals ( Mirounga leonina ) are being influenced by long‐term environmental change. These seals migrate up to 4,000 km from their breeding colonies, foraging for months in a variety of Southern Ocean habitats. Understanding how movement patterns vary with environmental features and how these relationships differ among in iduals employing different foraging strategies can provide insight into foraging performance at a population level. We apply new fast‐estimation tools to fit mixed effects within a random walk movement model, rapidly inferring among‐in idual variability in southern elephant seal environment–movement relationships. We found that seals making foraging trips to the sea ice on or near the Antarctic continental shelf consistently reduced speed and directionality (move persistence) with increasing sea‐ice coverage but had variable responses to chlorophyll a concentration, whereas seals foraging in the open ocean reduced move persistence in regions where circumpolar deep water shoaled. Given future climate scenarios, open‐ocean foragers may encounter more productive habitat but sea‐ice foragers may see reduced habitat availability. Our approach is scalable to large telemetry data sets and allows flexible combinations of mixed effects to be evaluated via model selection, thereby illuminating the ecological context of animal movements that underlie habitat usage.
Publisher: The Royal Society
Date: 16-05-2005
Abstract: Cetacean strandings elicit much community and scientific interest, but few quantitative analyses have successfully identified environmental correlates to these phenomena. Data spanning 1920–2002, involving a total of 639 stranding events and 39 taxa groups from southeast Australia, were found to demonstrate a clear 11–13- year periodicity in the number of events through time. These data positively correlated with the regional persistence of both zonal (westerly) and meridional (southerly) winds, reflecting general long-term and large-scale shifts in sea-level pressure gradients. Periods of persistent zonal and meridional winds result in colder and presumably nutrient-rich waters being driven closer to southern Australia, resulting in increased biological activity in the water column during the spring months. These observations suggest that large-scale climatic events provide a powerful distal influence on the propensity for whales to strand in this region. These patterns provide a powerful quantitative framework for testing hypotheses regarding environmental links to strandings and provide managers with a potential predictive tool to prepare for years of peak stranding activity.
Publisher: Cold Spring Harbor Laboratory
Date: 22-12-2020
DOI: 10.1101/2020.12.21.20248467
Abstract: This study examined the COVID-19 risk perceptions and mental health of university students on returning to c us in the midst of the COVID-19 pandemic. An online survey was completed during the first four weeks of the academic year (October 2020) by 897 university students. The survey included demographics and measures of experiences of COVID-19 testing, self-isolation, shielding, perceived risk, mental health and indices capturing related psychological responses to the pandemic. We observed higher levels of depression and anxiety, but not stress, in students compared with pre- pandemic normative data, but lower than levels reported earlier in the pandemic in other similar cohorts. Depression, anxiety and stress were independently associated with greater loneliness and reduced positive mood. Greater worry about COVID-19 was also independently associated with anxiety and stress. Female students and those with pre-existing mental health disorders were at greatest risk of poor mental health outcomes. Although students perceived themselves at only moderate risk of COVID-19, the prevalence of depression and anxiety among university students should remain a concern. Universities should provide adequate support for students’ mental health during term-time. Interventions to reduced loneliness and worry, and improve mood, may benefit students’ overall mental well-being.
Publisher: Public Library of Science (PLoS)
Date: 07-2015
Publisher: Wiley
Date: 04-2009
DOI: 10.2193/2007-461
Publisher: Wiley
Date: 25-11-2020
Publisher: Cambridge University Press (CUP)
Date: 06-2002
DOI: 10.1017/S0954102002000688
Abstract: This study is the first to describe the winter distribution of crabeater seals ( Lobodon carcinophagus ) in East Antarctica. The study was conducted in the Mertz Glacier Polynya region from July to August 1999. In total 89 crabeater seals were seen in 26 groups which ranged in size from 1 to 35 animals (mean = 3.2). The mean observed haulout density along a 200 m wide strip transect was 0.108 seals per km 2 , or 0.042 groups per km 2 . Crabeater seals were not uniformly distributed in the polynya but selected areas of stable ice over shallow ( 1000 m) waters. We used a generalized linear model to assess the relationship of seal distribution to the physical attributes of sea ice concentration, thickness, and ocean depth. We found that ice thickness and ocean depth were the most important determinants of seal distribution. Crabeater seals occurred in areas where the ice affords them a stable haulout platform while allowing them access to Antarctic krill that live directly beneath the ice.
Publisher: Public Library of Science (PLoS)
Date: 09-02-2022
DOI: 10.1371/JOURNAL.PONE.0262901
Abstract: Mechanisms promoting coexistence between closely related species are fundamental for maintaining species ersity. Mechanisms of niche differentiation include allochrony which offsets the peak timing of resource utilisation between species. Many studies focus on spatial and temporal niche partitioning during the breeding season, few have investigated the role allochrony plays in influencing interspecific segregation of foraging distribution and ecology between congeneric species during the non-breeding season. We investigated the non-breeding migrations of Snares ( Eudyptes robustus ) and Fiordland penguins ( Eudyptes pachyrhynchus ), closely related species breeding between 100–350 km apart whose migration phenology differs by two months. Using light geolocation tracking, we examined the degree of overlap given the observed allochrony and a hypothetical scenario where the species commence migration simultaneously. We found that Fiordland penguins migrated to the Sub-Antarctic Frontal Zone and Polar Frontal Zone in the austral autumn whereas Snares penguins disperse westwards staying north of the Sub-Tropical Front in the austral winter. Our results suggest that allochrony is likely to be at the root of segregation because the relative profitability of the different water masses that the penguins forage in changes seasonally which results in the two species utilising different areas over their core non-breeding periods. Furthermore, allochrony reduces relatively higher levels of spatiotemporal overlap during the departure and arrival periods, when the close proximity of the two species’ colonies would cause the birds to congregate in similar areas, resulting in high interspecific competition just before the breeding season. Available evidence from other studies suggests that the shift in phenology between these species has arisen from adaptive radiation and phenological matching to the seasonality of local resource availability during the breeding season and reduced competitive overlap over the non-breeding season is likely to be an incidental outcome.
Publisher: Inter-Research Science Center
Date: 29-05-2009
DOI: 10.3354/MEPS08010
Publisher: Elsevier BV
Date: 08-2007
Publisher: Wiley
Date: 27-07-2021
DOI: 10.1002/ECE3.7919
Abstract: The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food web structure, but long‐term data are required to study these effects. Southern elephant seals ( Mirounga leonina ) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilized or are increasing. Two long‐term mark‐recapture studies (1956–1967 and 1993–2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. Using a 9‐state matrix population model, we estimated climate influences on female survival by incorporating two major climatic indices into our model: The Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Our best model included a 1 year lagged effect of SAM and an unlagged SOI as covariates. A positive relationship with SAM1 (lagged) related the previous year's SAM with juvenile survival, potentially due to changes in local prey availability surrounding Macquarie Island. The unlagged SOI had a negative effect on both juvenile and adult seals, indicating that sea ice dynamics and access to foraging grounds on the East Antarctic continental shelf could explain the different contributions of ENSO events on the survival of females in this population.
Publisher: Springer Science and Business Media LLC
Date: 21-07-2023
DOI: 10.1038/S43247-023-00928-W
Abstract: Poor coverage of the Antarctic continental shelf bathymetry impedes understanding the oceanographic processes affecting Antarctica’s role in global climate. Continental shelf bathymetry influences warm modified Circumpolar Deep Water movement onto the shelf, making it an important factor promoting ice shelf melting and influencing the flow of ice shelves into the ocean. Building on previous work using seal es to redefine bathymetry, our longitudinal study of ocean physics and animal behaviour provided new depth information from over 500,000 in idual seal es on the East Antarctic continental shelf. About 25% of these seal es were 220 m (sometimes over 1000 m) deeper than the interpolated seafloor from IBCSO V2. Focusing on four well-s led regions, we show that the bathymetry of 22% to 60% of the s led area was improved by incorporating seal e data. This revealed new bathymetric features, including troughs off the Shackleton Ice Shelf and Underwood Glacier and a deep canyon near the Vanderford Glacier. This deep canyon, the Mirounga-Nuyina Canyon , was confirmed by a recent multi-beam echo sounder survey. Further acquisitions of seal data will improve our understanding and modelling of Antarctic coastal ocean processes and ice-sheet dynamics.
Publisher: Springer Science and Business Media LLC
Date: 16-04-2018
Publisher: Wiley
Date: 12-04-2010
Publisher: Wiley
Date: 09-11-2022
DOI: 10.1111/GCB.16500
Abstract: Anthropogenic climate change is resulting in spatial redistributions of many species. We assessed the potential effects of climate change on an abundant and widely distributed group of ing birds, Eudyptes penguins, which are the main avian consumers in the Southern Ocean in terms of biomass consumption. Despite their abundance, several of these species have undergone population declines over the past century, potentially due to changing oceanography and prey availability over the important winter months. We used light‐based geolocation tracking data for 485 in iduals deployed between 2006 and 2020 across 10 of the major breeding locations for five taxa of Eudyptes penguins. We used boosted regression tree modelling to quantify post‐moult habitat preference for southern rockhopper ( E. chrysocome ), eastern rockhopper ( E. filholi ), northern rockhopper ( E. moseleyi ) and macaroni/royal ( E. chrysolophus and E. schlegeli ) penguins. We then modelled their redistribution under two climate change scenarios, representative concentration pathways RCP4.5 and RCP8.5 (for the end of the century, 2071–2100). As climate forcings differ regionally, we quantified redistribution in the Atlantic, Central Indian, East Indian, West Pacific and East Pacific regions. We found sea surface temperature and sea surface height to be the most important predictors of current habitat for these penguins physical features that are changing rapidly in the Southern Ocean. Our results indicated that the less severe RCP4.5 would lead to less habitat loss than the more severe RCP8.5. The five taxa of penguin may experience a general poleward redistribution of their preferred habitat, but with contrasting effects in the (i) change in total area of preferred habitat under climate change (ii) according to geographic region and (iii) the species (macaroni/royal vs. rockhopper populations). Our results provide further understanding on the regional impacts and vulnerability of species to climate change.
Publisher: Elsevier BV
Date: 08-2013
Publisher: Public Library of Science (PLoS)
Date: 03-04-2013
Publisher: Wiley
Date: 08-01-2018
DOI: 10.1111/DDI.12702
Publisher: Springer Science and Business Media LLC
Date: 02-2008
DOI: 10.1038/NATURE06518
Abstract: Many free-ranging predators have to make foraging decisions with little, if any, knowledge of present resource distribution and availability. The optimal search strategy they should use to maximize encounter rates with prey in heterogeneous natural environments remains a largely unresolved issue in ecology. Lévy walks are specialized random walks giving rise to fractal movement trajectories that may represent an optimal solution for searching complex landscapes. However, the adaptive significance of this putative strategy in response to natural prey distributions remains untested. Here we analyse over a million movement displacements recorded from animal-attached electronic tags to show that erse marine predators-sharks, bony fishes, sea turtles and penguins-exhibit Lévy-walk-like behaviour close to a theoretical optimum. Prey density distributions also display Lévy-like fractal patterns, suggesting response movements by predators to prey distributions. Simulations show that predators have higher encounter rates when adopting Lévy-type foraging in natural-like prey fields compared with purely random landscapes. This is consistent with the hypothesis that observed search patterns are adapted to observed statistical patterns of the landscape. This may explain why Lévy-like behaviour seems to be widespread among erse organisms, from microbes to humans, as a 'rule' that evolved in response to patchy resource distributions.
Publisher: Elsevier BV
Date: 08-2008
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2003
End Date: 2005
Funder: Australian Research Council
View Funded ActivityStart Date: 2003
End Date: 2003
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 2021
Funder: Australian Research Council
View Funded Activity