ORCID Profile
0000-0002-2471-7511
Current Organisations
Australian Antarctic Division
,
University of Tasmania
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 29-09-2023
Publisher: American Geophysical Union (AGU)
Date: 21-10-2019
DOI: 10.1029/2019GL084347
Abstract: The emperor penguin, an iconic species threatened by projected sea ice loss in Antarctica, has long been considered to forage at the fast ice edge, presumably relying on large/yearly persistent polynyas as their main foraging habitat during the breeding season. Using newly developed fine‐scale sea icescape data and historical penguin tracking data, this study for the first time suggests the importance of less recognized small openings, including cracks, flaw leads and ephemeral short‐term polynyas, as foraging habitats for emperor penguins. The tracking data retrieved from 47 emperor penguins in two different colonies in East Antarctica suggest that those penguins spent 23% of their time in ephemeral polynyas and did not use the large/yearly persistent, well‐studied polynyas, even if they occur much more regularly with predictable locations. These findings challenge our previous understanding of emperor penguin breeding habitats, highlighting the need for incorporating fine‐scale seascape features when assessing the population persistence in a rapidly changing polar environment.
Publisher: Elsevier BV
Date: 12-2019
Publisher: Wiley
Date: 11-07-2003
Publisher: Oxford University Press (OUP)
Date: 26-05-2017
Abstract: Policy- and decision-makers require assessments of status and trends for marine species, habitats, and ecosystems to understand if human activities in the marine environment are sustainable, particularly in the face of global change. Central to many assessments are statistical and dynamical models of populations, communities, ecosystems, and their socioeconomic systems and management frameworks. The establishment of a national system that could facilitate the development of such model-based assessments has been identified as a priority for addressing management challenges for Australia’s marine environment. Given that most assessments require cross-scale information, in idual models cannot capture all of the spatial, temporal, biological, and socioeconomic scales that are typically needed. Coupling or integrating models across scales and domains can expand the scope for developing comprehensive and internally consistent, system-level assessments, including higher-level feedbacks in social–ecological systems. In this article, we summarize: (i) integrated modelling for marine systems currently being undertaken in Australia, (ii) methods used for integration and comparison of models, and (iii) improvements to facilitate further integration, particularly with respect to standards and specifications. We consider future needs for integrated modelling of marine social–ecological systems in Australia and provide a set of recommendations for priority focus areas in the development of a national approach to integrated modelling. These recommendations draw on—and have broader relevance for—international efforts around integrated modelling to inform decision-making for marine systems.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.CUB.2017.11.072
Abstract: In their 2015 Current Biology paper, Streby et al.[1] reported that Golden-winged Warblers (Vermivora chrysoptera), which had just migrated to their breeding location in eastern Tennessee, performed a facultative and up to ">1,500 km roundtrip" to the Gulf of Mexico to avoid a severe tornadic storm. From light-level geolocator data, wherein geographical locations are estimated via the timing of sunrise and sunset, Streby et al.[1] concluded that the warblers had evacuated their breeding area approximately 24 hours before the storm and returned about five days later. The authors presented this finding as evidence that migratory birds avoid severe storms by temporarily moving long-distances. However, the tracking method employed by Streby et al.[1] is prone to considerable error and uncertainty. Here, we argue that this interpretation of the data oversteps the limits of the used tracking technique. By calculating the expected geographical error range for the tracked birds, we demonstrate that the hypothesized movements fell well within the geolocators' inherent error range for this species and that such deviations in latitude occur frequently even if in iduals remain stationary.
Publisher: Oxford University Press (OUP)
Date: 08-2002
Publisher: Elsevier BV
Date: 09-2019
Publisher: Wiley
Date: 20-07-2018
DOI: 10.1111/GCB.14377
Abstract: The Southern Ocean is currently experiencing major environmental changes, including in sea-ice cover. Such changes strongly influence ecosystem structure and functioning and affect the survival and reproduction of predators such as seabirds. These effects are likely mediated by reduced availability of food resources. As such, seabirds are reliable eco-indicators of environmental conditions in the Antarctic region. Here, based on 9 years of sea-ice data, we found that the breeding success of Adélie penguins (Pygoscelis adeliae) reaches a peak at intermediate sea-ice cover (ca. 20%). We further examined the effects of sea-ice conditions on the foraging activity of penguins, measured at multiple scales from in idual es to foraging trips. Analysis of temporal organisation of es, including fractal and bout analyses, revealed an increasingly consistent behaviour during years with extensive sea-ice cover. The relationship between several e parameters and sea-ice cover in the foraging area appears to be quadratic. In years of low and high sea-ice cover, in iduals adjusted their ing effort by generally ing deeper, more frequently and by resting at the surface between es for shorter periods of time than in years with intermediate sea-ice cover. Our study therefore suggests that sea-ice cover is likely to affect the reproductive performance of Adélie penguins through its effects on foraging behaviour, as breeding success and most ing parameters share a common optimum. Some years, however, deviated from this general trend, suggesting that other factors (e.g. precipitation during the breeding season) might sometimes become preponderant over the sea-ice effects on breeding and foraging performance. Our study highlights the value of monitoring fitness parameters and in idual behaviour concomitantly over the long-term to better characterize optimal environmental conditions and potential resilience of wildlife. Such an approach is crucial if we want to anticipate the effects of environmental change on Antarctic penguin populations.
Publisher: Inter-Research Science Center
Date: 17-01-2019
DOI: 10.3354/MEPS12811
Publisher: Elsevier BV
Date: 2013
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: Wiley
Date: 31-08-2018
DOI: 10.1111/DDI.12830
Publisher: Springer Science and Business Media LLC
Date: 11-12-2017
DOI: 10.1038/S41559-017-0392-3
Abstract: Most seafloor communities at depths below the photosynthesis zone rely on food that sinks through the water column. However, the nature and strength of this pelagic-benthic coupling and its influence on the structure and ersity of seafloor communities is unclear, especially around Antarctica where ecological data are sparse. Here we show that the strength of pelagic-benthic coupling along the East Antarctic shelf depends on both physical processes and the types of benthic organisms considered. In an approach based on modelling food availability, we combine remotely sensed sea-surface chlorophyll-a, a regional ocean model and diatom abundances from sediment grabs with particle tracking and show that fluctuating seabed currents are crucial in the redistribution of surface productivity at the seafloor. The estimated availability of suspended food near the seafloor correlates strongly with the abundance of benthic suspension feeders, while the deposition of food particles correlates with decreasing suspension feeder richness and more abundant deposit feeders. The modelling framework, which can be modified for other regions, has broad applications in conservation and management, as it enables spatial predictions of key components of seafloor bio ersity over vast regions around Antarctica.
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/WR03101
Abstract: Hot-iron brands were used to mark permanently 14 000 six-week-old southern elephant seal (Mirounga leonina L.) pups at Macquarie Island between 1993 and 2000. We assessed temporal changes in the quality of 4932 brands applied in 1998 and 1999 to determine the duration of the brand wound, and the relationships between brand healing, brand readability and the amount of skin and hair damage peripheral to the brand characters. Most (98%) brand wounds were healed within one year. Brand-mark healing, peripheral skin damage and brand readability were significantly (P 0.05) correlated. The proportion of healed and readable brands increased in the population during the first annual moult, and thereafter these proportions remained high ( %) for the marked population. The mean number of brand characters with peripheral skin damage decreased significantly over the same period. The seal’s annual hair and skin moult is the process that contributed most to the healing of brand wounds. We also assessed our branding technique to determine whether any of the features we measured contributed to a poor-quality brand. Excessive pressure used during brand-iron application is the most probable cause of unsightly peripheral skin damage, but this damage is short lived.
Publisher: American Geophysical Union (AGU)
Date: 15-10-2016
DOI: 10.1002/2016GL070846
Abstract: Overwintering of larvae underneath Antarctic pack ice is a critical stage in the life cycle of Antarctic krill. However, there are no circumpolar assessments of available habitat for larval krill, making it difficult to evaluate how climate change may impact this life stage. We use outputs from a circumpolar sea ice model, together with a set of simple assumptions regarding key habitat features, to identify possible regions of larval krill habitat around Antarctica during winter. We assume that the location and suitability of habitat is determined by both food availability and three‐dimensional complexity of the sea ice. A comparison of the combined area of these regions under current conditions with a warm climate scenario indicates that while total areal sea ice extent decreases, there is a consistently larger area of potential larval krill habitat under warm conditions. These findings suggest that decreases in sea ice extent may not necessarily be detrimental for krill populations.
Publisher: Wiley
Date: 25-06-2020
Abstract: Light-level geolocator tags use ambient light recordings to estimate the whereabouts of an in idual over the time it carried the device. Over the past decade, these tags have emerged as an important tool and have been used extensively for tracking animal migrations, most commonly small birds. Analysing geolocator data can be daunting to new and experienced scientists alike. Over the past decades, several methods with fundamental differences in the analytical approach have been developed to cope with the various caveats and the often complicated data. Here, we explain the concepts behind the analyses of geolocator data and provide a practical guide for the common steps encompassing most analyses - annotation of twilights, calibration, estimating and refining locations, and extraction of movement patterns - describing good practices and common pitfalls for each step. We discuss criteria for deciding whether or not geolocators can answer proposed research questions, provide guidance in choosing an appropriate analysis method and introduce key features of the newest open-source analysis tools. We provide advice for how to interpret and report results, highlighting parameters that should be reported in publications and included in data archiving. Finally, we introduce a comprehensive supplementary online manual that applies the concepts to several datasets, demonstrates the use of open-source analysis tools with step-by-step instructions and code and details our recommendations for interpreting, reporting and archiving.
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: Wiley
Date: 06-09-2020
Abstract: Ecological niche theory predicts sympatric species to show segregation in their spatio-temporal habitat utilization or diet as a strategy to avoid competition. Similarly, within species in iduals may specialize on specific dietary resources or foraging habitats. Such in idual specialization seems to occur particularly in environments with predictable resource distribution and limited environmental variability. Still, little is known about how seasonal environmental variability affects segregation of resources within species and between closely related sympatric species. The aim of the study was to investigate the foraging behaviour of three closely related and sympatrically breeding fulmarine petrels (Antarctic petrels Thalassoica antarctica, cape petrels Daption capense and southern fulmars Fulmarus glacialoides) in a seasonally highly variable environment (Prydz Bay, Antarctica) with the aim of assessing inter- and intraspecific overlap in utilized habitat, timing of foraging and diet and to identify foraging habitat preferences. We used GPS loggers with wet/dry sensors to assess spatial habitat utilization over the entire breeding season. Trophic overlap was investigated using stable isotope analysis based on blood, feathers and egg membranes. Foraging locations were identified using wet/dry data recorded by the GPS loggers and expectation-maximization binary clustering. Foraging habitat preferences were modelled using generalized additive models and model cross-validation. During incubation and chick-rearing, the utilization distribution of all three species overlapped significantly and species also overlapped in the timing of foraging during the day-partly during incubation and completely during chick-rearing. Isotopic centroids showed no significant segregation between at least two species for feathers and egg membranes, and among all species during incubation (reflected by blood). Within species, there was no in idual specialization in foraging sites or environmental space. Furthermore, no single environmental covariate predicted foraging activity along trip trajectories. Instead, best-explanatory environmental covariates varied within and between in iduals even across short temporal scales, reflecting a highly generalist behaviour of birds. Our results may be explained by optimal foraging theory. In the highly productive but spatio-temporally variable Antarctic environment, being a generalist may be key to finding mobile prey-even though this increases the potential for competition within and among sympatric species.
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: Elsevier BV
Date: 12-2017
Publisher: Public Library of Science (PLoS)
Date: 13-09-2017
Publisher: Public Library of Science (PLoS)
Date: 13-10-2009
Publisher: Springer Science and Business Media LLC
Date: 13-11-2017
DOI: 10.1038/S41559-017-0368-3
Abstract: A dominant Antarctic ecological paradigm suggests that winter sea ice is generally the main feeding ground for krill larvae. Observations from our winter cruise to the southwest Atlantic sector of the Southern Ocean contradict this view and present the first evidence that the pack-ice zone is a food-poor habitat for larval development. In contrast, the more open marginal ice zone provides a more favourable food environment for high larval krill growth rates. We found that complex under-ice habitats are, however, vital for larval krill when water column productivity is limited by light, by providing structures that offer protection from predators and to collect organic material released from the ice. The larvae feed on this sparse ice-associated food during the day. After sunset, they migrate into the water below the ice (upper 20 m) and drift away from the ice areas where they have previously fed. Model analyses indicate that this behaviour increases both food uptake in a patchy food environment and the likelihood of overwinter transport to areas where feeding conditions are more favourable in spring.
Publisher: Elsevier BV
Date: 12-2008
Publisher: Inter-Research Science Center
Date: 05-10-2006
DOI: 10.3354/MEPS323263
Publisher: Wiley
Date: 27-09-2018
DOI: 10.1111/ECOG.03080
Publisher: Wiley
Date: 12-04-2010
Publisher: Canadian Science Publishing
Date: 12-2006
DOI: 10.1139/Z06-164
Abstract: Foraging by adult male otariids, a demographic component that often interacts with commercial fisheries, are poorly known. To assess movement patterns and habitat use, nine adult male Australian fur seals ( Arctocephalus pusillus doriferus Wood Jones, 1925) from Seal Rocks, in northern Bass Strait, southeastern Australia, were tracked for periods ranging from 66 to 223 d during 1999–2001. Mean ± SD at-sea and on-land durations were 6.9 ± 2.1 d (range 2.3–10.3 d, n = 9 seals) and 2.4 ± 0.9 d (range 0.8–4.1 d), respectively. All seals foraged almost exclusively in continental shelf waters and mostly (65%–97% of time at sea) in water columns that were between 40 and 100 m deep. Six of nine seals tracked for d spent 64%–98% of their time-at-sea foraging at distances km from Seal Rocks, although the maximum distance achieved from the colony was 1208 km. The seals’ foraging ranges overlapped with the ranges of operation of virtually all fin-fish fisheries in southeastern Australia, but fisheries overlap was low in the most frequented foraging area of central-western Bass Strait.
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: 25-03-2013
Publisher: American Geophysical Union (AGU)
Date: 08-2018
DOI: 10.1029/2018JC013932
Publisher: Frontiers Media SA
Date: 07-08-2019
Publisher: Wiley
Date: 08-01-2018
DOI: 10.1111/DDI.12702
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 05-2011
Publisher: Elsevier BV
Date: 2019
Publisher: Springer Science and Business Media LLC
Date: 17-09-2019
Publisher: Elsevier BV
Date: 12-2004
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: Elsevier BV
Date: 02-2003
No related grants have been discovered for Michael Sumner.