Washington harbor seal stable isotope data ...

• Main Author: Feddern, Megan
• Format: Dataset
• Language: English
• Published: Dryad 2022
• Subjects: compound specific stable isotope analysis; amino acid; trophic position; harbor seal; Washington; FOS Biological sciences; Hake; Pacific
• Online Access: https://dx.doi.org/10.5061/dryad.zs7h44jbg; https://datadryad.org/stash/dataset/doi:10.5061/dryad.zs7h44jbg

Understanding the response of predators to ecological change at multiple temporal scales can elucidate critical predator-prey dynamics that would otherwise go unrecognized. We performed compound-specific nitrogen stable isotope analysis (CSIA) of amino acids on 153 harbor seal museum skull specimens to determine how trophic position of this marine predator has responded to ecosystem change over the past century. The relationships between harbor seal trophic position, ocean condition, and prey abundance, were analyzed using hierarchical modelling of a multi-amino acid framework and applying 1-, 2-, and 3- year temporal lags. We identified delayed responses of harbor seal trophic position to both physical ocean conditions (upwelling, sea surface temperature, freshwater discharge) and prey availability (Pacific hake, Pacific herring and Chinook salmon). However, the magnitude and direction of the trophic position response to ecological changes depended on the temporal delay. For example, harbor seal trophic ... : Collagen samples were analyzed for using 5 mg of purified collagen from approximately 50 mg of bone. Preliminary analyses were conducted to determine the highest rate of collagen return from bone sampled from different parts of the skull to minimize destruction (mandible, internal occipital shelf, temporal process). All produced similar stable isotope measurements. Samples were primarily taken from the internal occipital shelf at the back of the skull to maintain external integrity. Bone was decalcified using 0.2 M HCl for 24-72 hours depending on bone thickness, followed by centrifugation and nanopure water rinse. Removal of humic acids was conducted using 0.125 M NaOH for 20 hours. Samples were washed to a neutral pH, then solubilized in 0.01N HCl. Once solubilized, samples were dried under a stream of N2 and freeze dried. Freeze dried collagen was analyzed for bulk isotopic composition of nitrogen by the UW IsoLab (isolab.ess.washington.edu) using a coupled elemental analyzer-isotope ratio mass ...