Stable isotopes reveal food web dynamics of a data-poor deep-sea island slope community (original) (raw)

Deep-sea communities are subject to a growing number of extrinsic pressures, which threaten their structure and function. Here we use carbon and nitrogen stable isotopes to provide new insights into the community structure of a data-poor deep-sea island slope system, the Exuma Sound, the Bahamas. A total of 78 individuals from 16 species were captured between 462 m and 923 m depth, and exhibited a broad range of δ 13 C (9.45‰) and δ 15 N (6.94‰). At the individual-level, δ 13 C decreased strongly with depth, indicative of shifting production sources, as well as potential shifts in community composition, and species-specific feeding strategies. δ 15 N did not follow strong depth relationships, suggesting trophic level and depth are not tightly coupled across individuals. We observed ontogenetic enrichment in δ 13 C and δ 15 N for Squalus cubensis (Cuban dogfish) highlighting a shift to larger, higher trophic level prey through ontogeny. These data provide the first assessment of food-web structure in the Exuma Sound, and suggest inherent complexity associated with deep-sea island slope ecosystems. Such observations are needed to further our understanding and develop contemporary management plans for these systems.