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Patterns of feeding and growth of Atlantic salmon Salmo salar L. in the marine environment are critical to understanding how observed declines in recruitment may reflect warming or other oceanic drivers. The isotopic composition of scales can provide insight into differences in marine feeding location and possibly temperature regime. The authors used archived scale samples to measure δ13C and δ15N deposited in the scales of one sea‐winter (1SW) salmon during their last season of growth at sea before they returned to five Irish rivers. δ13C values were related statistically to observed salmon body condition (Fulton's K), and fish with higher δ13C values tended to show significantly better condition. In contrast, δ15N values were negatively related to body condition. There was no important effect on condition of length at smolt migration, and the effect of duration of marine residence varied among rivers. It is likely that δ13C values partly reflected ambient ocean temperature and recent marine feeding environment before return migration, such that the observed relationship between higher δ13C values and increased body condition may express an advantage for adult fish feeding in warmer, potentially closer, waters. If greater body condition influences fitness, then a changing temperature regime in the Northeast Atlantic may drive shifts in salmon survival and reproduction. This study provides evidence that there is spatial and trophic variation at sea between salmon from rivers of origin that are located relatively close to each other, with potential consequences for body condition and, consequently, fitness and life history; this suggests that salmon populations from geographically proximate rivers within regions may exhibit differential responses to ocean‐scale climatic changes across the Northeast Atlantic. [ABSTRACT FROM AUTHOR]

Seasonal differences in the availability of resources potentially result in the food web architecture also varying through time. Stable isotope analyses are a logistically simple but powerful tool for inferring trophic interactions and food web structure, but relatively few studies quantify seasonal variations in the food web structure or nutrient flux across multiple trophic levels. We determined the temporal dynamics in stable isotope compositions (carbon, nitrogen and sulphur) of a fish community from a highly seasonal, temperate estuary sampled monthly over a full annual cycle. Sulphur isotope values in fish tissues discriminated among consumers exploiting pelagic and benthic resources but showed no seasonal variation. This implied limited change in the relative consumption of pelagic and benthic resources by the fish community over the study period despite major seasonal changes in phytoplankton biomass. Conversely, carbon and nitrogen isotope values exhibited seasonality marked by the commencement of the spring phytoplankton bloom and peak chlorophyll concentration, with δ13C values following expected trends in phytoplankton growth physiology and variation in δ15N values coinciding with changes in major nitrogen sources to plankton between nitrate and ammonium. Isotope shifts in fish muscle were detected within 2 weeks of the peak spring phytoplankton bloom, suggesting a rapid trophic transfer of carbon and nitrogen along food chains within the estuarine food web during periods of high production. Therefore we caution against the assumption that temporal averaging effectively dampens isotopic variability in tissues of higher trophic‐level animals in highly dynamic ecosystems, such as temperate estuaries. This work highlights how stable isotope analyses can be combined with environmental data to gain a broader understanding of ecosystem functioning, while emphasising the need for temporally appropriate sampling in stable isotope‐based studies. [ABSTRACT FROM AUTHOR]

Animal movements and resource utilization are essential factors for effective environmental management, but they are difficult to quantify in extensive natural ecosystems such as the aquatic environment.Stable isotope analysis is an ecological tracer technique that reveals information about links between trophic levels, movement patterns of migratory species or geographical variations due to the different aquatic processes that influence them. The Caspian kutum is an important commercial endemic species on the southern coasts of the Caspian Sea and can be used as a proxy to gain information on how different spatiotemporal, environmental and biological—variables can influence ecological tracers such as stable isotopes at the sea basin level. Thus, the main objective of this study is to investigate how spatiotemporal, isotopic baseline and environmental factors influence the distribution of stable isotopes in the Caspian kutum.The results showed that although there are individual variations, there is an overall increasing trend in δ13C and a decreasing trend in δ15N from the western to the eastern regions. In addition, there is a decreasing trend in δ13C and an increasing trend in δ15N with increasing age. It seems that among other migration routes of this species from the northern part of the southern Caspian Sea to the southern coasts, one of the main migration routes of this fish on the coasts of Iran is west‐east mobility, which may affect the efficiency of sustainable management of the catch in various fishing areas.This was the first study to establish a migratory pattern of the Caspian kutum based on stable isotopes. We advocate the wider stable isotopes to effectively investigate fish migratory, as the results from this study provided important contributions to the development of valuable insights for the management and sustainability for this threatened and declining species fish populations. [ABSTRACT FROM AUTHOR]

Accurate age estimates are crucial for assessing the life‐histories of fish and providing management advice, but validation studies are rare for many species. We corroborated age estimates with annual cycles of oxygen isotopes (δ18O) in otoliths of 86 northern pike (Esox lucius) from the southern Baltic Sea, compared results with visual age estimates from scales and otoliths, and assessed bias introduced by different age‐estimation structures on von Bertalanffy growth models and age‐structured population models. Age estimates from otoliths were accurate, while age estimates from scales significantly underestimated the age of pike older than 6 years compared to the corroborated reference age. Asymptotic length (L∞) was larger, and the growth coefficient k was lower for scale ages than for corroborated age and otolith age estimates. Consequentially, scale‐informed population models overestimated maximum sustainable yield (MSY), biomass at MSY (BMSY), relative frequency of trophy fish (≥100cm), and optimal minimum length limit but underestimated fishing mortality at MSY (FMSY). Using scale‐based ages to inform management regulations for pike may therefore result in conservative management and lost yield. The overestimated asymptotic length may instill unrealistic expectations of trophy potential in recreational anglers targeting large pike, while the overestimation in MSY would cause unrealistic expectations of yield potential in commercial fishers. [ABSTRACT FROM AUTHOR]

Copyright of Methods in Ecology & Evolution is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A rapidly warming Arctic Ocean and associated sea‐ice decline is resulting in changing sea‐ice protist communities, affecting productivity of under‐ice, pelagic, and benthic fauna. Quantifying such effects is hampered by a lack of biomarkers suitable for tracing specific basal resources (primary producers and microorganisms) through food webs. We investigate the potential of δ13C values of essential amino acids (EAAs) (δ13CEAA values) to estimate the proportional use of diverse basal resources by organisms from the under‐ice (Apherusa glacialis), pelagic (Calanus hyperboreus) and benthic habitats (sponges, sea cucumber), and the cryo‐pelagic fish Boreogadus saida. Two approaches were used: baseline δ13CEAA values, that is, the basal resource specific δ13CEAA values, and δ13CEAA fingerprints, or mean‐centred baseline δ13CEAA values. Substantial use of sub‐ice algae Melosira arctica by all studied organisms suggests that its role within Arctic food webs is greater than previously recognized. In addition, δ13CEAA fingerprints from algae‐associated bacteria were clearly traced to the sponges, with an individually variable kelp use by sea cucumbers. Although mean‐centred δ13CEAA values in A. glacialis, C. hyperboreus, and B. saida tissues were aligned with microalgae resources, they were not fully represented by the filtered pelagic‐ and sea‐ice particulate organic matter constituting the spring diatom‐dominated algal community. Under‐ice and pelagic microalgae use could only be differentiated with baseline δ13CEAA values as similar microalgae clades occur in both habitats. We suggest that δ13CEAA fingerprints combined with microalgae baseline δ13CEAA values are an insightful tool to assess the effect of ongoing changes in Arctic basal resources on their use by organisms. [ABSTRACT FROM AUTHOR]

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, individuals 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 sampled 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 individual 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 individual females throughout their breeding cycle. Finally, individual specialization indices revealed that each of the study populations contain specialist individuals that utilize only a small subset of the total population niche width. The degree of individual 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 individual variability when assessing the foraging ecology of marine predators. [ABSTRACT FROM AUTHOR]

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 (δ18Obiomin), where we expect to see universally expressed and predictable spatial variation in δ18Obiomin values across taxa. We constructed global ocean isoscapes of predicted δ18Obiomin values specific to fish (otoliths), cephalopod (statoliths) and shellfish (shells), and a fourth combined "universal" isoscape, and evaluated their capacity to derive δ18Obiomin values among known‐origin samples. High correspondence between isoscape‐predicted δ18Obiomin values and a compiled database of measured, georeferenced values (3954 datapoints encompassing 68 species) indicated that this δ18Obiomin approach works effectively, particularly in regions with highly resolved projections of seawater δ18O 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 sample origins amongst regions of divergent (Tropical Asia vs Temperate Australasia) and similar (Temperate Asia vs Temperate Australasia) climates and latitudes. Classification accuracy averaged 75.3% between divergent regions, and 66% between similar regions. When endothermic tuna species were excluded from the analysis, the accuracy between divergent regions increased up to 90% between divergent 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. [ABSTRACT FROM AUTHOR]

Summary: The traditional separation between primary producers (autotrophs) and consumers (heterotrophs) at the base of the marine food web is being increasingly replaced by the paradigm that mixoplankton, planktonic protists with the nutritional ability to use both phago(hetero)trophy and photo(auto)trophy to access energy are widespread globally. Thus, many 'phytoplankton' eat, while 50% of 'protozooplankton' also perform photosynthesis. Mixotrophy may enhance primary production, biomass transfer to higher trophic levels and the efficiency of the biological pump to sequester atmospheric CO2 into the deep ocean. Although this view is gaining traction, science lacks a tool to quantify the relative contributions of autotrophy and heterotrophy in planktonic protists. This hinders our understanding of their impacts on carbon cycling within marine pelagic ecosystems. It has been shown that the hydrogen (H) isotopic signature of lipids is uniquely sensitive to heterotrophy relative to autotrophy in plants and bacteria. Here, we explored whether it is also sensitive to the trophic status in protists. The new understanding of H isotope signature of lipid biomarkers suggests it offers great potential as a novel tool for quantifying the prevalence of mixotrophy in diverse marine microorganisms and thus for investigating the implications of the 'mixoplankton' paradigm. [ABSTRACT FROM AUTHOR]

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 (>40°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 δ13C and δ15N 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. Key Points: First carbon and nitrogen isoscape predictions of the entire Southern Ocean, based on particulate organic matter isotope dataClear spatial gradients in δ13C and δ15N values were predicted, consistent with previously reported isotopic variability in this regionKey implications for the use of isoscape baselines in animal studies attempting to document seasonal migratory or foraging behaviors [ABSTRACT FROM AUTHOR]

Fishes are the dominant vertebrates in the ocean, yet we know little of their contribution to carbon export flux at regional to global scales. We synthesize the existing information on fish‐based carbon flux in coastal and pelagic waters, identify gaps and challenges in measuring this flux and approaches to address them, and recommend research priorities. Based on our synthesis of passive (fecal pellet sinking) and active (migratory) flux of fishes, we estimated that fishes contribute an average (± standard deviation) of about 16.1% (± 13%) to total carbon flux out of the euphotic zone. Using the mean value of model‐generated global carbon flux estimates, this equates to an annual flux of 1.5 ± 1.2 Pg C yr−1. High variability in estimations of the fish‐based contribution to total carbon flux among previous field studies and reported here highlight significant methodological variations and observational gaps in our present knowledge. Community‐adopted methodological standards, improved and more frequent measurements of biomass and passive and active fluxes of fishes, and stronger linkages between observations and models will decrease uncertainty, increase our confidence in the estimation of fish‐based carbon flux, and enable identification of controlling factors to account for spatial and temporal variability. Better constraints on this key component of the biological pump will provide a baseline for understanding how ongoing climate change and harvest will affect the role fishes play in carbon flux. [ABSTRACT FROM AUTHOR]

Throughout their life history, many animals transition among heterogeneous environments to facilitate behaviours such as reproduction, foraging and predator avoidance. The dynamic environmental and biological conditions experienced by mobile species are integrated in the chemical composition of their tissues, providing retrospective insight into movement.Here, we present a unique application of nitrogen stable isotope clocks ('isotopic clocks'), which integrate tissue turnover rates, consumer stable isotope ratios and habitat‐specific isotope baselines to predict time‐since‐immigration and the timing of habitat shifts in a migratory species. Nitrogen stable isotope values of blood plasma collected from juvenile sand tiger sharks Carcharias taurus, a species known to undertake seasonal movements between ocean and estuarine environments, were used to derive estimates of time‐since‐immigration and the timing of seasonal habitat shifts undertaken by this species.Nitrogen isotopic clocks estimated for 65 juvenile sand tiger sharks sampled across 6 years indicated that individual sharks predominantly arrived to estuarine habitats between June and July, with some individuals arriving as early as mid‐May. These estimates were validated by comparing isotope‐derived estuarine arrival times with those from acoustically tracked individuals. The median estuarine arrival day estimates from our isotopic approach aligned with estimates from acoustic telemetry for each sampling population.Sensitivity analyses indicated that isotopically inferred time‐since‐immigration and estuarine arrival estimates were robust to variation in isotopic turnover rate and diet tissue discrimination factors under multiple modelling scenarios. This suggests that parameterization of the nitrogen isotopic clock provides reliable estimates of time‐since‐immigration and day of arrival into new habitats if isotopic variation exists between origin and new locations.Our study presents a unique application of telemetry‐validated isotope clocks to derive retrospective estimates of time‐since‐immigration and timing of habitat shifts for animals that seasonally traverse heterogeneous environments. This approach can be readily applied across many temporal and spatial scales, and to other species and ecosystems, to facilitate rapid assessment of changes in animal habitat use and broader ecosystem structure. [ABSTRACT FROM AUTHOR]

Tracking habitat use and dietary shifts in migratory species is vital to conservation and management. Yet, conventional animal tracking often precludes tracking small juveniles at critical life stages where recruitment bottlenecks often manifest.Stable isotope analysis (SIA) in consecutive laminae in eye lenses, a protein‐rich depositional tissue, has emerged as a promising tool in fishes to develop long‐term interpretive records of dietary histories using a single archival tissue. Currently, studies using fish eye lenses to study SIA in diets have primarily been conducted in marine environments using δ13C and δ15N to identify resource partitioning, ontogenetic shifts and lifelong trophic histories. To date, no studies have examined freshwater taxa nor used δ34S isotopes.We placed juvenile (Chinook Salmon) Oncorhynchus tshawytscha in experimental enclosures in three different freshwater habitats (hatchery, river and seasonal floodplain), each with isotopically distinct and well‐characterized food webs. This experimental approach allowed us to directly measure diets and quantify tissue turnover rates in eye lenses as well as the isotopic fractionation among fish tissues (fin and muscle tissue) in distinct habitat types using stable isotopes δ13C, δ15N and δ34S.Bulk eye‐lens stable isotope measurements were analysed for juvenile salmon lenses and were found to be consistent with the isotopic values of rearing habitats. Slight additional isotopic fractionation was only found in δ13C. We then successfully applied the method to a larger, reproductively mature adult salmon captured in freshwater and inferred juvenile habitat use.SIA in eye lenses using three dietary isotopes (δ13C, δ15N and δ34S) has significant potential for answering critical questions about migration, diet, foraging ecology and life history of migratory aquatic animals on Earth. Such information would have immediate application towards conservation management of diverse species and habitats at multiple scales. [ABSTRACT FROM AUTHOR]

The relationship between physiology and temperature has a large influence on population‐level responses to climate change. In natural settings, direct thermal effects on metabolism may be exaggerated or offset by behavioural responses influencing individual energy balance. Drawing on a newly developed proxy, we provide the first estimates of the thermal performance curve of field metabolism in a wild fish. We investigate the thermal sensitivity of field metabolic rate in two sympatric, genetically distinct ecotypes of Atlantic cod from the Skagerrak coast of southern Norway. The combined ecotype median of field metabolic rate increased with increasing temperature until around 16°C, coincident with the thermal optimum for growth for juvenile Atlantic cod. Individual cod experienced temperatures in excess of the thermal optimum for field metabolic rate, indicating some degree of thermal limitation of field metabolism in a complex natural environment with the potential for thermal refugia. The two cod ecotypes showed different thermal performance curves for field metabolic rate, revealing that genetic components to temperature sensitivity persist beyond acclimation effects. The cold‐adapted fjord ecotype maintained higher field metabolic rates at cooler temperatures than the warm‐adapted North Sea ecotype, which showed clear preference for warmer waters around the thermal optimum. Field metabolic rates of the two ecotypes were strongly influenced by year and location of sampling, implying more complex behavioural responses to environmental conditions. We emphasise that the energy uses reflecting physiological conditions in the field should be considered in the evaluation of the effect of climatic variables on fish population dynamics and demonstrate that otolith isotopes provide an analytical framework to answer this question. [ABSTRACT FROM AUTHOR]

Rationale: The presence of lipids in animal tissues can influence the interpretation of stable isotope data, particularly in lipid‐rich tissues such as the skin and muscle of marine mammals. The traditionally employed chloroform–methanol delipidation protocol has the potential to alter δ15N values in proteinaceous tissues. Our objective was to determine whether the use of cyclohexane could be an alternative extraction method, effectively removing lipids without altering δ15N values. Methods: Kidney, liver, muscle, and skin samples were collected from beach‐cast Sowerby's beaked whales (Mesoplodon bidens). Control subsamples were processed without delipidation extraction, and duplicate subsamples were extracted with either chloroform–methanol or cyclohexane. δ13C, δ15N, and C:N values were determined by continuous‐flow elemental analysis isotope ratio mass spectrometry. Paired Wilcoxon tests were used to evaluate the change in isotope ratios after extraction, and unpaired Wilcoxon tests were used to evaluate differences in isotope ratios between extractions. Results: Use of cyclohexane is an effective delipidation technique for tissues with low and moderate lipid content. Chemical delipidation influenced δ15N values; extracted samples generally showed an increase in δ15N values which varied from 0.0‰ to 1.7‰. Chloroform–methanol extraction resulted in alterations to δ15N values greater than the analytical precision for all analyzed tissues. Changes to δ15N values after cyclohexane extraction were at or near the analytical precision for liver and muscle but greater than the analytical precision for kidney and skin. Conclusions: We recommend processing duplicate subsamples for stable isotope analysis, one with and one without extraction, in order to obtain accurate values for each isotope ratio. Prolonged chemical extractions are not necessary to effectively remove lipids. When samples are limited, we suggest using cyclohexane for tissues with low or moderate lipid content, and chloroform–methanol for lipid‐rich tissues. [ABSTRACT FROM AUTHOR]

Copyright of Methods in Ecology & Evolution is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Migratory animals pose difficult challenges to conservation and management because identifying critical habitats used throughout their lives is rarely possible. Endogenous tracers (e.g. isotope ratios) recorded in sequentially growing biogenic tissues, however, represent a potential source of unique insights at the more elusive temporal and spatial scales central to understanding the ecology of mobile species. To this end, a general probabilistic framework has emerged that quantitatively compares predictive models of isotopic variation across landscapes (called isoscapes) to the isotopic composition recorded in a biological tissue to determine the provenance and movements of animals throughout their lives.Although this spatially continuous approach to isotope‐based geographic assignment is becoming more common across taxa and ecosystems, adopting this framework to take advantage of serial isotope records stored within sequentially growing biogenic tissues (e.g. teeth or otoliths) is less common.Here, we construct a novel space‐time isotope model of provenance (STIMP) that determines the habitat use through time of migratory fish across river basins. To do so, this model integrates: strontium isotope (87Sr/86Sr) ratios across a riverscape, the serial records of 87Sr/86Sr within otoliths, habitat geomorphology and the directional movement patterns of fish through river networks.To illustrate an application of the model, we applied it to a published dataset from Chinook salmon (Oncorhynchus tshawytscha) harvested in 2011 during a coastal fishery in Bristol Bay, Alaska, U.S.A. Using this model, we show how individuals exploit an array of habitat types to achieve their juvenile growth prior to ocean migration, and that the intensity of habitat use among habitat types across the basin shifts spatially over the course of freshwater residence (e.g. from headwaters to migration corridors). The STIMP presented here integrates diverse information sources to reveal the cryptic juvenile movement patterns of a highly migratory species, providing new insights critical to their conservation. This general framework is applicable to any migratory taxa that use isotopically heterogeneous landscapes during their lives and record such variation in sequentially growing biogenic tissues. [ABSTRACT FROM AUTHOR]

In this paper, we revisit the state of deep‐water fisheries to the west of the British Isles and aim to provide an overview on the key drivers behind community changes along continental margins. The deep‐water fisheries to the west of the British Isles that extend from the shelf‐slope break down to the lower slope and along banks and seamounts of the Rockall Basin, mainly target blue ling Molva dypterygia, roundnose grenadier Coryphaenoides rupestris, orange roughy Hoplostethus atlanticus, with by‐catches of black scabbardfish Aphanopus carbo and tusk Brosme brosme. These fishing grounds experienced a long period of exhaustive exploitation until the early 2000s, but subsequently the implementation of management strategies has helped to relieve excessive fishing pressure. It is widely accepted that a better understanding of the long‐term implications of disturbance is needed to understand patterns in deep‐water communities and what sustainable use and exploitation of resources might look like in this context. [ABSTRACT FROM AUTHOR]

The exchange of energy and nutrients are integral components of ecological functions of benthic shallow‐water ecosystems and are directly dependent on in situ environmental conditions. Traditional laboratory experiments cannot account for the multidimensionality of interacting processes when assessing metabolic rates and biogeochemical fluxes of structurally complex benthic communities. Current in situ chamber systems are expensive, limited in their functionality and the deployment is often restricted to planar habitats (e.g. sediments or seagrass meadows) only.To overcome these constraints, we describe a protocol to build and use non‐invasive, cost‐effective and easy to handle in situ incubation chambers that provide reproducible measurements of biogeochemical processes in simple and structurally complex benthic shallow‐water communities. Photogrammetry tools account for the structural complexity of benthic communities, enabling to calculate accurate community fluxes. We tested the performance of the system in laboratory assays and various benthic habitats (i.e. algae growing on rock, coral assemblages, sediments and seagrass meadows). In addition, we estimated community budgets of photosynthesis and respiration by corals, rock with algae and carbonate sediments, which were subsequently compared to budgets extrapolated from conventional ex situ single‐organism incubations.The tests highlight the transparency (>90% light transmission) of the chambers and minimal water exchange with the surrounding medium on most substrates. Linear dissolved oxygen fluxes in dependence to incubation time showed sufficient mixing of the water by circulation pumps and no organismal stress response. The comparison to single‐organism incubations showed that ex situ measurements might overestimate community‐wide net primary production and underestimate respiration and gross photosynthesis by 20%–90%.The proposed protocol overcomes the paucity of observational and manipulative studies that can be performed in in situ native habitats, thus producing widely applicable and realistic assessments on the community level. Importantly, the tool provides a standardized approach to compare community functions across a wide range of benthic habitats. We identify multiple experimental strategies, including the manipulation of stressors/factors, and discuss how the method may be implemented in a variety of aquatic studies. [ABSTRACT FROM AUTHOR]

Spatial models of variation in the isotopic composition of structural nutrients across habitats (isoscapes) offer information on physical, biogeochemical and anthropogenic processes occurring across space, and provide a tool for retrospective assignment of animals or animal products to their foraging area or geographic origin. The isotopic differences among reference samples used to construct isoscapes may vary spatially and according to non‐spatial terms (e.g. sampling date, or among individual or species effects). Partitioning variance between spatially dependent and spatially independent terms is a critical but overlooked aspect of isoscape creation with important consequences for the design of studies collecting reference data for isoscape creation and the accuracy and precision of isoscape models.We introduce the use of integrated nested Laplace approximation (INLA) to construct isoscape models. Integrated nested Laplace approximation provides a computationally efficient framework to construct spatial models of isotopic variability explicitly addressing additional variation introduced by including multiple reference species (or other recognized sources of variance).We present carbon, nitrogen and sulphur isoscape models extending over c. 1 million km2 of the UK shelf seas. Models were built using seven different species of jellyfish as spatial reference data and a suite of environmental correlates. Compared to alternative isoscape prediction methods, INLA‐spatial isotope models show high spatial precision and reduced variance. We briefly discuss the likely biogeochemical explanations for the observed spatial isotope distributions. We show for the first time that sulphur isotopes display systematic spatial variation across open marine shelf seas and may therefore be a useful additional tool for marine spatial ecology.The INLA technique provides a promising tool for generating isoscape models and associated uncertainty surfaces where reference data are accompanied by multiple, quantifiable sources of uncertainty. [ABSTRACT FROM AUTHOR]

Taylor'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. This research reveals that aspects of community structure beyond species abundances vary with environment. The authors use Taylor's power law to quantify aggregation behaviour to show how the size‐structured North Sea fish community responds with local hydrography, highlighting its utility as an ecosystem metric. [ABSTRACT FROM AUTHOR]

Retrospective 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. [ABSTRACT FROM AUTHOR]

Trace element concentrations in fish earstones ('otoliths') are widely used to discriminate spatially discrete populations or individuals of marine fish, based on a commonly held assumption that physiological influences on otolith composition are minor, and thus variations in otolith elemental chemistry primarily reflect changes in ambient water chemistry., We carried out a long-term (1-year) experiment, serially sampling seawater, blood plasma and otoliths of mature and immature European plaice ( Pleuronectes platessa L.) to test relationships between otolith chemistry and environmental and physiological variables., Seasonal variations in otolith elemental composition did not track seawater concentrations, but instead reflected physiological controls on metal transport and biokinetics, which are likely moderated by ambient temperature. The influence of physiological factors on otolith composition was particularly evident in Sr/ Ca ratios, the most widely used elemental marker in applied otolith microchemistry studies. Reproduction also triggered specific variations in otolith and blood plasma metal chemistry, especially Zn/ Ca ratios in female fish, which could potentially serve as retrospective spawning indicators., The influence of physiology on the trace metal composition of otoliths may explain the success of microchemical stock discrimination in relatively homogenous marine environments, but could complicate alternative uses for trace element compositions in biominerals of higher organisms. [ABSTRACT FROM AUTHOR]

Over-exploitation of top predators and fish stocks has altered ecosystems towards less productive systems with fewer trophic levels. In the Celtic Sea ( CS), discards and bycatch levels have prompted concern about some fisheries, while fin and humpback whales are recovering from centuries of over-exploitation. A lack of empirical evidence on the preferred diet of some predators such as whales in the CS has hindered the implementation of effective conservation measures using an ecosystem-based approach to fisheries management. Using a Bayesian framework ( SIAR), stable carbon ( δ13C) and nitrogen ( δ15N) isotope mixing models were used to assign proportionate diet solutions to fin and humpback whales (skin biopsies) and putative prey items: herring ( Clupea harengus), sprat ( Sprattus sprattus), and krill ( Meganyctiphanes norvegica and Nyctiphanes couchii) in the CS. Krill was the single most important prey item in the diet of fin whales, but one of the least important for humpback whales (albeit based on a small sample of humpback whale samples). Age 0 sprat and herring comprised a large proportion of the diet of both species, followed by older sprat (age 1-2) and older herring (age 2-4). An ecosystem based approach to fisheries management will be required in the CS if we seek effective conservation of both fin and humpback whales, and sustainable fisheries. [ABSTRACT FROM AUTHOR]

Biomineralized 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. [ABSTRACT FROM AUTHOR]

RATIONALE Stable isotope values ( δ13C and δ15N) of darted skin and blubber biopsies can shed light on habitat use and diet of cetaceans, which are otherwise difficult to study. Non-dietary factors affect isotopic variability, chiefly the depletion of 13C due to the presence of 12C-rich lipids. The efficacy of post hoc lipid-correction models (normalization) must be tested. METHODS For tissues with high natural lipid content (e.g., whale skin and blubber), chemical lipid extraction or normalization is necessary. C:N ratios, δ13C values and δ15N values were determined for duplicate control and lipid-extracted skin and blubber of fin ( Balaenoptera physalus), humpback ( Megaptera novaeangliae) and minke whales ( B. acutorostrata) by continuous-flow elemental analysis isotope ratio mass spectrometry (CF-EA-IRMS). Six different normalization models were tested to correct δ13C values for the presence of lipids. RESULTS Following lipid extraction, significant increases in δ13C values were observed for both tissues in the three species. Significant increases were also found for δ15N values in minke whale skin and fin whale blubber. In fin whale skin, the δ15N values decreased, with no change observed in humpback whale skin. Non-linear models generally out-performed linear models and the suitability of models varied by species and tissue, indicating the need for high model specificity, even among these closely related taxa. CONCLUSIONS Given the poor predictive power of the models to estimate lipid-free δ13C values, and the unpredictable changes in δ15N values due to lipid-extraction, we recommend against arithmetical normalization in accounting for lipid effects on δ13C values for balaenopterid skin or blubber samples. Rather, we recommend that duplicate analysis of lipid-extracted ( δ13C values) and non-treated tissues ( δ15N values) be used. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Westbury Formation (Rhaetian) beds of Westbury Garden Cliff, Westbury-on-Severn, west of Gloucester, Britain, show an unusual combination of features. Both deep water and emergent characteristics are present within the sediments and the trace fossils. The ichnoassemblage consists of abundant Selenichnites, Planolites beverlyensis and Lockeia with rarer Oniscoidichnus, Chondrites, Rhizocorallium irregulare, Taenidium serpentium an unusual form of Walcottia and Merostomichnites-like traces. These trace fossils display an interesting relationship with the sediments: low-energy Cruziana ichnofacies is found within high-energy sandstones. The sandstones are interbedded with laminated mudstones, apparently deposited in deep water, but some aspects of the ichnoassemblage, preservation and sedimentation indicate shallower water. One new trace fossil, Radichnus allingtona igen. et isp. nov., closely resembles the traces of modern fiddler crabs and imply emergence, by analogy. This ichnofauna is similar to early stage disaster colonisation in recent experiments in Long Island Sound (south of Connecticut, USA) and with storm-influenced deposits within the Cardium Formation (Seebe, Alberta, Canada). This indicates a lagoonal environment with influxes of sand and oxygen. Total organic carbon levels were found to fluctuate greatly between stratigraphic layers but remained relatively high. This implies low oxygen conditions. The abundance of sulphur (in pyrite) also supports an interpretation of anoxic conditions, and low sedimentation rates within the shale layers. A restricted shallow basin or lagoonal environment is proposed for the palaeoenvironment, with fluctuating oxygen influencing diversity. [ABSTRACT FROM AUTHOR]

Rationale Methods Results Conclusion Increasing demand for fish and seafood means that the traceability of marine products is becoming ever more important for consumers, producers and regulators. Highly complex and globalised supply networks create challenges for verifying a stated catch region. Atlantic cod is one of the most commercially important species in the northeast Atlantic. Several regional fisheries supply cod into the trade network, of which some are at greater risk of overexploitation than others. Tools allowing retrospective testing of spatial origin would significantly assist sustainable harvesting of fish, reducing incentives for illegal fishing and fraud.Here, we investigate whether stable isotope ratios of carbon, nitrogen and sulphur can be used to retrospectively identify the catch region of Atlantic cod (Gadus morhua). We measured the isotopic composition of muscle tissue from 377 cod from 10 catch regions across the northeast Atlantic and then applied three different assignment methods to classify cod by region of most likely origin. The assignment method developed was subsequently tested using independently sourced, known‐origin samples.Individual cod could be traced back to their true origin with an average assignment accuracy of 70–79% and over 90% accuracy for certain regions. Assignment success rates comparable to those using genetic techniques were achieved when assigning among restricted and pre‐selected regions. However, assignment accuracy to the fishery region estimated from independent samples across the whole geographic range of cod averaged ~25% overall, highlighting the need for careful application of isotope‐based approaches.Stable isotope techniques can provide effective tools to test for origin in Atlantic cod, but not all catch regions are isotopically distinct. Stable isotopes could be combined with genetic techniques to result in higher assignment accuracy than could be achieved using either method independently. Assignment potential can be estimated from reference datasets, but estimates of realistic assignment accuracy require independently collected data. [ABSTRACT FROM AUTHOR]