1,721,063 research outputs found
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
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
Ontogenetic trends in resource partitioning and trophic geography of sympatric skates (Rajidae) inferred from stable isotope composition across eye lenses
No full textResource partitioning is expected in sympatric assemblages of predators as a mechanism that reduces competition between individuals of different species or age classes, which in turn can affect population and community interactions as well as resource distribution and availability. However, for species such as benthic skates (Rajidae), the juveniles of which are cryptic and not easily sampled by traditional survey methods, there is a knowledge gap concerning the spatial and trophic ecology during early life stages. The eye lenses of vertebrates grow over their lifetime providing a chronological biochemical record that can be used to infer differences in diet and/or foraging location (trophic geography) throughout the ontogeny of the animal. For the first time, eye lenses of 4 sympatric Rajidae species from the northeast Atlantic were successfully used to recover stable isotope life histories for individual skates. Isotopic separation among species and across life stages within species suggests that habitat partitioning and differences in trophic ecology are present throughout ontogeny. Isotopic data imply that adults are separated from juveniles both spatially and in terms of their diet and the 4 species appear to partition resources more than expected based on previous studies.</p
Data from: Stable isotope-based location in a shelf sea setting: accuracy and precision are comparable to light-based location methods
No full textRetrospective determination of location for marine animals would facilitate investigations of migration, connectivity and food provenance. Predictable spatial variations in carbon and nitrogen isotopes in primary production across shelf seas provide a basis for stable isotope-based location. Here, we assess the accuracy and precision that can be obtained through dietary-isotope-based location methods. We build isoscapes from jellyfish tissues and use these to assign scallops of fixed and known individual location, and herring with well-understood population-level distributions in the North Sea. Accuracy and precision for retrospective isotope-based location in the North Sea were of a similar order to light-based location devices, with 75% of individual scallops assigned correctly to areas representing c. 30% of the North Sea, with a mean linear error on the order of 102 km. Applying assignment methods to an alternative migratory species (herring) resulted in ecologically realistic assignments consistent with fisheries survey data. Location methods based on dietary isotopes such as carbon and nitrogen recover the spatial origin of nutrients assimilated into tissues, and this may not correspond directly to the physical location if either the test animal or its prey is highly migratory. Stable isotope-based location can be applied to any marine-feeding organism or derived food product, but the ecological meaning of any assigned area will be more difficult to interpret for large, high trophic level, migratory animals with relatively slow isotopic assimilation rates.,TableS1 Stable isotope results C. capillataLatitude, Longitude, Weight, Bell diameter, stable isotope (d15N, d13C) and CN ratio for individual C. capillata sampled across the North Sea in Sept 2015TableS1.txtTableS2 Stable isotope data from herring from the North SeaLocations of capture (lat, long) and stable isotope (d13C d15N) values for herring caught across the North Sea in Sept. 2011TableS2.txtJennings.2001Stable isotope data (lipid corrected d13C, d15N) from queen scallops published in Jennings &amp; Warr 2003 and Barnes et al., 2009</span
Individual trophic specialization in juvenile European seabass: implications for the management of a commercially important species
No full textIndividual differences in diet can play an important role defining a population's ecological niche and its role within food webs and habitats, but individual trophic specialization is rarely considered in a fisheries context. Stocks of European seabass, Dicentrarchus labrax, have declined in recent years, and policy has focused on managing fishing effort. Inshore nursery grounds represent a critical habitat in terms of recruitment to standing stocks, and improved understanding of the ecology of juvenile seabass at the level of the individual may assist the development of management strategies aimed at maximizing their survival and growth. We quantified levels of individual trophic specialization in juvenile seabass using stomach contents and stable isotope analyses at a monthly resolution over an annual cycle. We found significant, seasonally varying levels of individual specialization in stomach contents, with reduced specialization observed in the spring. This was corroborated by stable isotope analyses, where isotopic variance among seabass individuals was significantly higher compared to that in two other concurrently sampled, sympatric bentho-pelagic predators. Our findings suggest that juvenile seabass form trophic-generalist populations composed of specialized individuals. Considering variation in individual behaviours may improve management strategies aimed at protecting the vulnerable life stages of this commercially important species
Ecogeochemistry potential in deep time biodiversity illustrated using a modern deep-water case study
No full textThe fossil record provides the only direct evidence of temporal trends in biodiversity over evolutionary timescales. Studies of biodiversity using the fossil record are, however, largely limited to discussions of taxonomic and/or morphological diversity. Behavioural and physiological traits that are likely to be under strong selection are largely obscured from the body fossil record. Similar problems exist in modern ecosystems where animals are difficult to access. In this review, we illustrate some of the common conceptual and methodological ground shared between those studying behavioural ecology in deep time and in inaccessible modern ecosystems. We discuss emerging ecogeochemical methods used to explore population connectivity and genetic drift, life-history traits and field metabolic rate and discuss some of the additional problems associated with applying these methods in deep time
Visualizing fossilization using laser ablation–inductively coupled plasma–mass spectrometry maps of trace elements in Late Cretaceous bones
No full textElemental maps generated by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) provide a previously unavailable high-resolution visualization of the complex physicochemical conditions operating within individual bones during the early stages of diagenesis and fossilization. A selection of LA-ICP-MS maps of bones collected from the Late Cretaceous of Montana (United States) and Madagascar graphically illustrate diverse paths to recrystallization, and reveal unique insights into geochemical aspects of taphonomic history. Some bones show distinct gradients in concentrations of rare earth elements and uranium, with highest concentrations at external bone margins. Others exhibit more intricate patterns of trace element uptake related to bone histology and its control on the flow paths of pore waters. Patterns of element uptake as revealed by LA-ICP-MS maps can be used to guide sampling strategies, and call into question previous studies that hinge upon localized bulk samples of fossilized bone tissue. LA-ICP-MS maps also allow for comparison of recrystallization rates among fossil bones, and afford a novel approach to identifying bones or regions of bones potentially suitable for extracting intact biogeochemical signals
Data from: Trophic interactions of fish communities at midwater depths enhance long-term carbon storage and benthic production on continental slopes
No full textBiological transfer of nutrients and materials between linked ecosystems influences global carbon budgets and ecosystem structure and function. Identifying the organisms or functional groups that are responsible for nutrient transfer, and quantifying their influence on ecosystem structure and carbon capture is an essential step for informed management of ecosystems in physically distant, but ecologically linked areas. Here, we combine natural abundance stable isotope tracers and survey data to show that mid-water and bentho-pelagic-feeding demersal fishes play an important role in the ocean carbon cycle, bypassing the detrital particle flux and transferring carbon to deep long-term storage. Global peaks in biomass and diversity of fishes at mid-slope depths are explained by competitive release of the demersal fish predators of mid-water organisms, which in turn support benthic fish production. Over 50% of the biomass of the demersal fish community at depths between 500 and 1800 m is supported by biological rather than detrital nutrient flux processes, and we estimate that bentho-pelagic fishes from the UK–Irish continental slope capture and store a volume of carbon equivalent to over 1 million tonnes of CO2 every year.,Trueman 2014 Fish Isotope dataStable isotope data (d13C PDB and d15N air) from white muscle tissue of fishes caught by demersal trawl on the Rockall trough. Associated data are: Species name, feeding type (benthic or benthopelagic), capture (trawl) depth in meters and fish mass in grammes</span
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