1,721,129 research outputs found
Field metabolic rates of wild marine fishes: reviewing old questions with new data
No full textTime integrated Field Metabolic Rate (FMR) is arguably the most ecologically relevant measure of the energetics of wild animals, but the relative complexity of determining FMR routinely means that we have relatively few large datasets describing variation in energy use in free-living wild animals, particularly for aquatic ectotherms where double labelled water methods cannot be used. Emerging proxies based on stable isotope systematics associated with respiration allow retrospective estimation of time integrated field metabolic rate, experienced temperature and growth in any free living marine teleost fish. We have estimated FMR in over 1000 individual fish, across nearly 100 species. Here we draw on our data compilation to explore predictions for two contentious topics in fish ecophysiology: (1) Metabolic cold adaptation: We show that polar species have higher FMR than temperate but not tropical species at equivalent body sizes and temperatures, and that, within species, populations at the cold edge of the range express higher FMR but lower growth rates than populations at the warm edge of the species range. (2) Gill oxygen limitation theory: FMR data covering 4 orders of magnitude body size within single species show no strong evidence for reduction in metabolic capacity at large body sizes as predicted by the GOLT
Baleen stable isotope data
No full textThis dataset contains d13C and d15N stable isotope data from northern hemisphere rorqual whale (Balaenoptera) baleen taken from our collections. This includes data from the baleen of the Hintze Hall blue whale. The data has been used in various research papers. Additional data allow the analyses in these papers to be carried out and mostly encompass environmental datasets or the outputs of various simulation models. **Note that if trying to link these data to analyses in GitHub, an update to this site has changed all "." in column headers to "_". These will need to be changed before the code will work. Apologies.**</span
Chemical taphonomy of biomineralized tissues
No full textBiomineralized tissues are chemically altered after death, and this diagenetic alteration can obscure original biological chemical features or provide new chemical information about the depositional environment. To use the chemistry of fossil biominerals to reconstruct biological, environmental or taphonomic information, a solid appreciation of biomineralization, mineral diagenesis and biomineral–water interaction is needed. Here, I summarize the key recent developments in the fields of biomineralization and post-mortem trace element exchange that have significant implications for our understanding of the diagenetic behaviour of biominerals and the ways in which biomineral chemistry can be used in palaeontological and taphonomic research
Dataset: Otolith-derived field metabolic rates (C_resp values), experience temperatures and stable isotopes (δ13C and δ18O)
No full textThis dataset supports the Southampton Doctoral thesis entitled Macroecological study of otolith-derived field metabolic rates of marine fishes by Sarah R. Alewijnse
Otolith-derived field metabolic rates, reported as C_resp values; the proportion of metabolic carbon in a fishes blood (see Chung et al. 2019 Mar. Freshw. Res.), and otolith-derived experienced temperatures in degrees Celcius.
Also included are the δ13C and δ18O used to derive C_resp values and experienced temperature.
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Why do crystallinity values fail to predict the extent of diagenetic alteration of bone mineral?
No full textSpectroscopic indicators of bone crystallinity such as the infrared splitting factor (IRSF) are commonly used to determine the general state of preservation of ancient bone. In principle such indices might be expected to act as a proxy for alteration of bone mineral and thus could be used to screen bones (or portions of bones) for likely preservation of in vivo biogenic trace element and stable isotope signals. We tested the relationship between IRSF and bone mineral composition in two suites of well-characterised recent and Pleistocene bones. Initially, crystallinity change and trace element uptake are correlated, apparently both controlled by decomposition of the organic phase and exposure of bone crystal surfaces. This relationship breaks down in older bones where authigenic phosphate growth and mineral–pore water interactions are no longer rate-limited by the breakdown of collagen and exposure of crystal surfaces. In these conditions the extent of chemical alteration of bone will be controlled by site specific conditions, and thus while FTIR spectra of bone provide a broad indication of organic content and apatite recrystallisation, they are not reliable proxies for the degree of diagenetic alteration in terms of biogenic geochemical signals.<br/
Traceability of the Norway Lobster nephrops norvegicus in UK Shelf Seas: A stable isotope approach
No full textEnsuring sustainability of the world fisheries is a key conservation and economic objective. Traceability of seafood from the final sale back to the point of harvest is an important aspect, supporting both fishery management and consumer protection. Stable isotope–based geolocation can be applied to trace the spatial origin of seafood, drawing on comparisons between the isotopic compositions of the product and those of a reference dataset from known spatial locations. This study tests the extent to which stable isotope–based geolocation can be applied to identify catch location of the Norwegian lobster Nephrops norvegicus. Carbon, nitrogen, and sulfur isoscapes across UK shelf seas are used as the reference dataset and test the accuracy of assignment estimates using a variety of bivariate and multivariate stable isotope geolocation approaches. Two alternative Bayesian inversions, one balanced and one weighted, are applied to the outcomes of the statistical models to determine the most accurate methods of assignment. Of all the methods trialed, the multivariate approach using carbon, nitrogen, and sulfur isoscape data produced the most accurate assignments, with c. 60% of samples from each site correctly assigned among six possible fishery origins. Weighted Bayesian approaches resulted in more correct assignments to highly fished sites, but at a cost of reduced correct assignments to sites of low fishing activity. Processed Nephrops samples obtained from supermarkets were assigned to potential fishery location, with results indicating the majority were captured in the west of Scotland. The isoscape methods explored can be calibrated to any marine feeding organism and provide a useful tool for more efficient management of marine stocks
Trace element geochemistry of bonebeds
No full textThe geochemistry of bones within bonebeds can be used to infer aspects of burial history, post burial movement, and paleoenviornmental conditions. To use chemical methods, however, it is important to understand the mechanisms and rates of fossilisation of bone and incorporation of trace elements. This chapter reviews the current opinions concerning the nature of fossilisation, discusses (with reference to published case studies) the ways that trace element chemistry can be used to study bonebeds and provides a brief guide to the analysis of fossil bones
Trophic ecology of black scabbardfish, Aphanopus carbo in the NE Atlantic—Assessment through stomach content and stable isotope analyses
No full textThe black scabbardfish is a deep water species of high commercial interest in the NE Atlantic. Specimens were collected from commercial trawls to the west of the British Isles and from longliners operating near Madeira between September 2008 and May 2010. Stomach content analysis was confined to samples from the northern area, because of a high number of empty stomachs from Madeira. Stable isotope analyses identified that black scabbardfish feeds on species with epipelagic and benthopelagic affinities. For the west of British Isles, the ?N values were significantly different between seasons suggesting a change in the diet throughout the year. Black scabbardfish have higher ?N and ?C values compared with other co-occurring benthopelagic feeders and lower nitrogen values than the true benthic predators and/or scavengers. Comparison with stable isotope analysis in samples from Madeira indicated that black scabbardfish feed at a similar trophic level and has the same trophic niche width in both areas, assuming similar baseline isotope compositions. The diet in the northern area comprised fish (68% N), crustaceans (22% N) and cephalopods (15% N) with blue whiting (Micromesistius poutassou) constituting 40% of the prey. Seasonal shift in diet was observed, with a predominance of blue whiting (70%) in the first quarter of the year, shifting to a more diverse diet in the remainder of the year. These results indicate that the diet of black scabbardfish is closely linked with the seasonal migration of blue whiting and that they likely select prey in proportion to availability. This study demonstrates that the combined used of both methods can elucidate the trophic ecology of black scabbardfish, in situations where conventional methods alone provide insufficient data
Dataset in support of the thesis: Ocean to plate: Tracing the geographic origin of fish products using biochemical forensic techniques
No full textThis dataset contains all research data collected for the PhD thesis entitled 'Ocean to plate: Tracing the geographic origin of fish products using biochemical forensic techniques'. It consists of biochemical data measured in muscle tissue of Atlantic cod, haddock and European hake collected from a range of regions in the Northeast Atlantic Ocean in 2018, as well as in European glass eels collected from four European rivers. Data includes stable isotope ratios, fatty acid compositions and trace element compositions measured by x-ray fluorescence (XRF).</span
Taylor’s power law captures the effects of environmental variability on community structure: an example from fishes in the North Sea
No full textTaylor’s power law (TPL) describes the relationship between the mean and variance in abundance of populations, with the power law exponent considered a measure of aggregation. However the usefulness of TPL exponents as an ecological metric has been questioned, largely due to its apparent ubiquity in various complex systems. The aim of this study was to test whether TPL exponents vary systematically with potential drivers of animal aggregation in time and space, and therefore capture useful ecological information of the system of interest. We derived community TPL exponents from a long term, standardised and spatially dense data series of abundance and body size data for a strongly size-structured fish community in the North Sea. We then compared TPL exponents between regions of contrasting environmental characteristics. We find that, in general, TPL exponents vary more than expected under random conditions in the North Sea for size-based populations compared to communities considered by species. Further, size-based temporal TPL exponents are systematically higher (implying more temporally-aggregated distributions) along hydrographic boundaries. Time-series of size-based spatial TPL exponents also differ between hydrographically distinct basins. These findings support the notion that TPL exponents contain ecological information, capturing community spatio-temporal dynamics as influenced by external drivers
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