Trace me if you can: the use of intrinsic biogeochemical markers in marine top predators

Abstract

Human activities have serious impacts on marine apex predators. Inadequate knowledge of the spatial and trophic ecology of these marine animals ultimately compromises the viability of their populations and impedes our ability to use them as environmental biomonitors. Intrinsic biogeochemical markers, such as stable isotopes, fatty acids, trace elements, and chemical pollutants, are increasingly being used to trace the spatial and trophic ecology of marine top predators. Notable advances include the emergence of the first oceanographic “isoscapes” (isotopic geographic gradients), the advent of compound‐specific isotopic analyses, improvements in diet reconstruction through Bayesian statistics, and tissue analysis of tracked animals to ground‐truth biogeochemical profiles. However, most researchers still focus on only a few tracers. Moreover, insufficient knowledge of the biogeochemical integration in tissues, fractionation and routing processes, and geographic and temporal variability in baseline levels continue to hamper the resolution and potential of these markers in studying the spatial and feeding ecology of top predators.

Spatial and isotopic niche partitioning during winter in chinstrap and Adélie penguins from the South Shetland Islands

“…This suggests that large-scale migration patterns in Adélie and chinstrap penguins may be estimable from SIA of tail feathers. However, linking animal movement patterns with variation in tissue stable isotope values relies on an understanding of the timing of tissue synthesis and any possible lags between resource acquisition and mobilization for tissue growth (Bearhop et al 2002, Martínez del Rio et al 2009, Ramos and González-Solís 2012. Nonetheless, there are several lines of evidence to support our inference.…”

“…Feathers are metabolically inert following synthesis and therefore encapsulate an isotopic record of avian diets and foraging habitat use from when and where they were grown (Hobson 1999, Ramos andGonzález-Solís 2012). Therefore, we used data on the timing and rate of growth of tail feathers from a captive study, detailed in Appendix B, of Adélie penguins to select a 0.5-cm section from the shaft of each tail feather from GLS tracked individuals that was grown approximately 59611 and 69620 days following the onset of molt for chinstrap and Adélie penguins, respectively.…”

Seabirds as regional biomonitors of legacy toxicants on an urbanized coastline

“…However, tissues from migratory seabirds may have toxicants incorporated from both breeding and overwintering foraging areas, which hinders tracing the source of toxicants (Braune et al, 2002;Bond and Diamond, 2010). Additional samples from tissues formed at different times within the life cycle, such as feathers or otoliths formed overwinter outside of the breeding season, can further clarify geographic sources of contamination (Ramos and González-Solís, 2012;Lavoie et al, 2015).…”

“…sediment, bivalves, invertebrates, fish, and water to provide greater understanding of the pathway by which seabirds are exposed to toxicants in a food web. Identification of the exposure pathways may be supported using seabird diet, stable isotope, and telemetry data (Braune et al, 2002;Ramos and González-Solís, 2012). Additional efforts are needed to compare the contaminant levels in the SCB across these sample types.…”

Stable isotope analysis of vertebrae reveals ontogenetic changes in habitat in an endothermic pelagic shark

“…Therefore, the stable isotope compositions of different food webs provide the context within which a consumer's stable isotope composition can be used as tracers of habitat use, especially in migratory species [19][20][21]. This approach has been used to understand movements in marine organisms including marine mammals [22,23], seabirds [24], teleosts [25] and elasmobranchs [26].…”