MEPS 601:97-108 (2018)  -  DOI: https://doi.org/10.3354/meps12647

ABSTRACT: Bottom-up changes in the abundance and composition of primary producers and primary consumers can cascade through ecosystems. Zooplankton stable isotopes (δ¹³C and δ¹⁵N) can be used to determine the linkages between these bottom-up processes, as nutrients, community composition, and physical oceanographic variables can influence zooplankton stable isotopes. However, the expression and variability in zooplankton stable isotopes remain poorly constrained and understood in many systems. Here, we explored how environmental and community variability influences zooplankton stable isotope ratios in the eastern Bering Sea across a wide range of ocean conditions. We tested whether there were interannual, spatial, or climate-driven shifts in the δ¹⁵N and δ¹³C of zooplankton. We found considerable variability across the eastern Bering Sea, with significant differences in isotopes among years, regions, and depths. These patterns were driven by differences in zooplankton community and physical oceanographic variables such as sea surface temperature. Effects were consistent across isotopes, and reflect the shared influences of oceanographic parameters and nutrients on δ¹³C and δ¹⁵N at the base of the food web.

KEY WORDS: Stable isotope · Isoscape · Chlorophyll a · Nitrate · Climate change