Marine & Environmental Sciences Faculty Reports

Document Type

Report

Publication Date

4-1997

Keywords

Exxon Valdez oil spill, Food webs, Harbor seals, δ13C, δ15N, Isotope ratios, Phoca vitulina, Prince William Sound

Abstract

This project consists of two components: (1) provision of analytical services for the stable isotope ratio investigations associated with Exxon Valdez oil spill projects, and (2) an investigation of food web relationships and trophic interactions of harbor seals and other top consumers of Prince William Sound (PWS). Through the use of harbor seal tissues collected from native harvested animals and tagging programs, seasonal and migrational information has been obtained with regard to prey utilization and trophic status at differing locations within the sound and the adjacent Gulf of Alaska. Preliminary results indicate that within PWS, harbor seals fall at the top of food chains based on locally derived productivity. Isotope ratios along whiskers grown over the past year indicate, however, that some individuals migrate into areas (presumably in the Gulf of Alaska) wherein the food web structure has different carbon and nitrogen isotope ratios. Isotope ratios indicate that offshore primary productivity is lower than in PWS and may reflect long-term declines observed in the western Gulf of Alaska and Bering Sea. Findings from experiments with captive seals to determine whisker growth rates indicate faster whisker growth rates in spring following pupping and molting and slower growth in the winter.

Report Number

Restoration Project 96170

Publication Title

Exxon Valdez Oil Spill Restoration Project Annual Report

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