ORCID Profile
0000-0002-4995-736X
Current Organisation
University of Southampton
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Ecological Impacts of Climate Change | Ecological Applications | Behavioural Ecology
Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) | Antarctic and Sub-Antarctic Oceanography | Ecosystem Assessment and Management of Antarctic and Sub-Antarctic Environments |
Publisher: Wiley
Date: 07-09-2022
DOI: 10.1111/FAF.12703
Abstract: Identifying the source of seafood is critical for combatting seafood fraud, but current tools are predominantly developed and applied on a species‐specific basis. This study investigates how multiple marine taxa could be geolocated at global scales by exploiting stable oxygen isotope compositions in carbonate biominerals (δ 18 O biomin ), where we expect to see universally expressed and predictable spatial variation in δ 18 O biomin values across taxa. We constructed global ocean isoscapes of predicted δ 18 O biomin values specific to fish (otoliths), cephalopod (statoliths) and shellfish (shells), and a fourth combined “universal” isoscape, and evaluated their capacity to derive δ 18 O biomin values among known‐origin s les. High correspondence between isoscape‐predicted δ 18 O biomin values and a compiled database of measured, georeferenced values (3954 datapoints encompassing 68 species) indicated that this δ 18 O biomin approach works effectively, particularly in regions with highly resolved projections of seawater δ 18 O composition. When compared to taxon‐specific isoscapes, the universal isoscape demonstrated similar accuracy, indicating exciting potential for universal provenance applications. We tested the universal framework via a case study, using machine‐learning models to identify s le origins amongst regions of ergent (Tropical Asia vs Temperate Australasia) and similar (Temperate Asia vs Temperate Australasia) climates and latitudes. Classification accuracy averaged 75.3% between ergent regions, and 66% between similar regions. When endothermic tuna species were excluded from the analysis, the accuracy between ergent regions increased up to 90% between ergent regions. This study presents the first empirical step towards developing universal chemical markers, which have the potential to support a more inclusive and global approach of validating provenance of seafood.
Publisher: Elsevier BV
Date: 02-2013
Publisher: Springer Science and Business Media LLC
Date: 07-08-2022
DOI: 10.1007/S11160-022-09720-Z
Abstract: Chemical analysis of calcified structures continues to flourish, as analytical and technological advances enable researchers to tap into trace elements and isotopes taken up in otoliths and other archival tissues at ever greater resolution. Increasingly, these tracers are applied to refine age estimation and interpretation, and to chronicle responses to environmental stressors, linking these to ecological, physiological, and life-history processes. Here, we review emerging approaches and innovative research directions in otolith chemistry, as well as in the chemistry of other archival tissues, outlining their value for fisheries and ecosystem-based management, turning the spotlight on areas where such biomarkers can support decision making. We summarise recent milestones and the challenges that lie ahead to using otoliths and archival tissues as biomarkers, grouped into seven, rapidly expanding and application-oriented research areas that apply chemical analysis in a variety of contexts, namely: (1) supporting fish age estimation (2) evaluating environmental stress, ecophysiology and in idual performance (3) confirming seafood provenance (4) resolving connectivity and movement pathways (5) characterising food webs and trophic interactions (6) reconstructing reproductive life histories and (7) tracing stock enhancement efforts. Emerging research directions that apply hard part chemistry to combat seafood fraud, quantify past food webs, as well as to reconcile growth, movement, thermal, metabolic, stress and reproductive life-histories provide opportunities to examine how harvesting and global change impact fish health and fisheries productivity. Ultimately, improved appreciation of the many practical benefits of archival tissue chemistry to fisheries and ecosystem-based management will support their increased implementation into routine monitoring. Graphical abstract
Publisher: Wiley
Date: 02-2023
DOI: 10.1002/ECE3.9790
Abstract: Information on resource use and trophic dynamics of marine predators is important for understanding their role in ecosystem functioning and predicting population‐level responses to environmental change. Where separate populations experience different local environmental conditions, geographic variability in their foraging ecology is often expected. Within populations, in iduals also vary in morphology, physiology, and experience, resulting in specialization in resource use. In this context, isotopic compositions of incrementally grown tissues such as keratinous hairs offer a valuable opportunity to study long‐term variation in resource and habitat use. We investigated the trophic ecology of female Cape fur seals ( Arctocephalus pusillus pusillus ) using carbon and nitrogen isotopic compositions of serially s led whiskers collected at four breeding sites along the coast of South Africa. Drawing on over 900 isotopic measurements, we assessed geographic variability in isotopic niche width between colonies and the degree of in idual specialization. We found slight, but clear geographic differences in isotopic ratios and isotopic niche widths, seemingly related to ecological setting, with niche widths being proportional to the area of available shelf and shelf‐slope habitat surrounding the colony. We further identified periodic oscillations in isotopic ratios, which likely reflect temporal patterns in foraging distribution and prey type, linked to shifts in the availability of prey resources and their interaction with constraints on in idual females throughout their breeding cycle. Finally, in idual specialization indices revealed that each of the study populations contain specialist in iduals that utilize only a small subset of the total population niche width. The degree of in idual specialization was, however, not consistent across colonies and may reflect an interactive influence between density‐dependent effects and habitat heterogeneity. Overall, this study provides important information on the trophic ecology of Cape fur seals breeding in South Africa and highlights the need to consider geographic and in idual variability when assessing the foraging ecology of marine predators.
Publisher: Springer Science and Business Media LLC
Date: 12-09-2022
Publisher: Inter-Research Science Center
Date: 09-08-2018
DOI: 10.3354/MEPS12667
Publisher: Elsevier BV
Date: 09-2007
DOI: 10.1016/J.ACA.2007.08.015
Abstract: Ten international laboratories participated in an inter-laboratory comparison of a fossil bone composite with the objective of producing a matrix and structure-matched reference material for studies of the bio-mineralization of ancient fossil bone. We report the major and trace element compositions of the fossil bone composite, using in-situ method as well as various wet chemical digestion techniques. For major element concentrations, the intra-laboratory analytical precision (%RSD(r)) ranges from 7 to 18%, with higher percentages for Ti and K. The %RSD(r) are smaller than the inter-laboratory analytical precision (%RSD(R) <15-30%). Trace element concentrations vary by approximately 5 orders of magnitude (0.1 mg kg(-1) for Th to 10,000 mg kg(-1) for Ba). The intra-laboratory analytical precision %RSD(r) varies between 8 and 45%. The reproducibility values (%RSD(R)) range from 13 to 100% was found for the high field strength elements (Hf, Th, Zr, Nb). The rare earth element (REE) concentrations, which vary over 3 orders of magnitude, have %RSD(r) and %RSD(R) values at 8-15% and 20-32%, respectively. However, the REE patterns (which are very important for paleo-environmental, taphonomic and paleo-oceanographic analyses) are much more consistent. These data suggest that the complex and unpredictable nature of the mineralogical and chemical composition of fossil bone makes it difficult to set-up and calibrate analytical instruments using conventional standards, and may result in non-spectral matrix effects. We propose an analytical protocol that can be employed in future inter-laboratory studies to produce a certified fossil bone geochemical standard.
Publisher: Proceedings of the National Academy of Sciences
Date: 31-05-2005
Abstract: Recent claims for continent wide disappearance of megafauna at 46.5 thousand calendar years ago (ka) in Australia have been used to support a “blitzkrieg” model, which explains extinctions as the result of rapid overkill by human colonizers. A number of key sites with megafauna remains that significantly postdate 46.5 ka have been excluded from consideration because of questions regarding their stratigraphic integrity. Of these sites, Cuddie Springs is the only locality in Australia where megafauna and cultural remains are found together in sequential stratigraphic horizons, dated from 36-30 ka. Verifying the stratigraphic associations found here would effectively refute the rapid-overkill model and necessitate reconsideration of the regional impacts of global climatic change on megafauna and humans in the lead up to the last glacial maximum. Here, we present geochemical evidence that demonstrates the coexistence of humans and now-extinct megafaunal species on the Australian continent for a minimum of 15 ka.
Publisher: Cambridge University Press (CUP)
Date: 26-07-2012
DOI: 10.1017/S2040174412000542
Abstract: During foetal development, calcium requirements are met as a consequence of maternal adaptations independent of vitamin D status. In contrast, after birth, dependency on vitamin D appears necessary for calcium metabolism and skeletal health. We used a rodent model (Sprague-Dawley rats), to determine if maternal vitamin D deficiency during pregnancy had a deleterious effect on bone structure at birth. Vitamin D deplete females were maintained under deplete conditions until birth of the pups, whereupon all dams were fed a vitamin D replete diet. Offspring were harvested at birth, and 140 days of age. Bones were analyzed using micro-computed tomography and strength tested to study differences in bone structure, density and strength and subjected to elemental analysis using plasma mass spectrometry to determine strontium, barium and calcium contents. Offspring from deplete mothers displayed altered trabecular parameters in the femur at birth and 140 days of age. In addition, at 140 days of age there was evidence of premature mineralization of the secondary ossification centre of the femoral head. Elemental analysis showed increased strontium uptake in the femur of the developmentally vitamin D-deficient offspring. Vitamin D depletion during development in the offspring may have a long-lasting effect, despite repletion of vitamin D from birth. This may have consequences for human health given the low vitamin D levels seen during pregnancy and current lifestyle of sun avoidance due to the risk of skin cancer.
Publisher: Frontiers Media SA
Date: 03-12-2020
DOI: 10.3389/FMARS.2020.594636
Abstract: Determining the geographic range of widely dispersed or migratory marine organisms is notoriously difficult, often requiring considerable costs and typically extensive tagging or exploration programs. While these approaches are accurate and can reveal important information on the species, they are usually conducted on only a small number of in iduals and can take years to produce relevant results, so alternative approaches may be preferable. The presence of latitudinal gradients in stable carbon isotope compositions of marine phytoplankton offers a means to quickly determine likely geographic population ranges of species that rely on productivity from these resources. Across sufficiently large spatial and temporal scales, the stable carbon isotopes of large coastal or pelagic marine species should reflect broad geographic patterns of resource use, and could be used to infer geographic ranges of marine populations. Using two methods, one based on a global mechanistic model and the other on targeted low-cost latitudinal s ling of fishes, we demonstrate and compare these stable isotope approaches to determine the core population geography of an apex predator, the great hammerhead ( Sphyrna mokarran ). Both methods indicated similar geographic ranges and suggested that S. mokarran recorded in south-eastern Australia are likely to be from more northern Australian waters. These approaches could be replicated in other areas where coastlines span predictable geographic gradients in isotope values and be used to determine the core population geography of highly mobile species to inform management decisions.
Publisher: Elsevier BV
Date: 10-2020
Publisher: American Geophysical Union (AGU)
Date: 09-2021
DOI: 10.1029/2020GB006901
Abstract: Polar marine ecosystems are particularly vulnerable to the effects of climate change. Warming temperatures, freshening seawater, and disruption to sea‐ice formation potentially all have cascading effects on food webs. New approaches are needed to better understand spatiotemporal interactions among biogeochemical processes at the base of Southern Ocean food webs. In marine systems, isoscapes (models of the spatial variation in the stable isotopic composition) of carbon and nitrogen have proven useful in identifying spatial variation in a range of biogeochemical processes, such as nutrient utilization by phytoplankton. Isoscapes provide a baseline for interpreting stable isotope compositions of higher trophic level animals in movement, migration, and diet research. Here, we produce carbon and nitrogen isoscapes across the entire Southern Ocean ( °S) using surface particulate organic matter isotope data, collected over the past 50 years. We use Integrated Nested Laplace Approximation‐based approaches to predict mean annual isoscapes and four seasonal isoscapes using a suite of environmental data as predictor variables. Clear spatial gradients in δ 13 C and δ 15 N values were predicted across the Southern Ocean, consistent with previous statistical and mechanistic views of isotopic variability in this region. We identify strong seasonal variability in both carbon and nitrogen isoscapes, with key implications for the use of static or annual average isoscape baselines in animal studies attempting to document seasonal migratory or foraging behaviors.
Publisher: Springer Science and Business Media LLC
Date: 18-01-2018
DOI: 10.1038/S41559-017-0432-Z
Abstract: Sharks are a erse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain in iduals that forage within additional isotopically erse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.
Publisher: Elsevier BV
Date: 11-2022
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 07-2021
End Date: 12-2024
Amount: $497,000.00
Funder: Australian Research Council
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