Grantee Research Project Results
Tidal Currents and the Control of Energy Flow in a Marine Food Web
EPA Grant Number: U915017Title: Tidal Currents and the Control of Energy Flow in a Marine Food Web
Investigators: Zamon, Jeannette E.
Institution: University of California - Irvine
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 1996 through January 1, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Fellowship - Marine Biology , Academic Fellowships , Biology/Life Sciences
Objective:
The objective of my research project is to: (1) to test the hypothesis that tidal currents create predictable energy flow to marine predators by controlling the distribution of organisms at the base of the food web; and (2) to develop a conceptual model of energy transfer that allows one to predict how three types of human disturbance (fishery activity, acute pollution, and chronic pollution) are likely to affect the food web in northern Puget Sound, WA.
Approach:
Oceanographers have proposed that tidal currents control energy flow to upper level consumers by causing predictable changes in the distribution of small, drifting organisms (plankton) at the base of the food web. Small fish, which eat plankton, should track these tidal changes in plankton distribution. In turn, fish predators should track changes in fish distribution. To test this hypothesis, I needed to quantify the distribution, abundance, and feeding activity of tertiary consumers (seabirds and seals), secondary consumers (schooling fishes), and primary consumers (plankton) versus tidal phase. Sampling periods were designed to quantify rates and locations of predator feeding activity for each tidal phase. I used a 120 kHz, single-beam echosounder to measure tidal changes in fish distribution and relative abundance along predetermined transects. I used a dip net to capture planktivorous fish for identification and diet analysis. I sampled plankton densities at different tides and locations with a fine-mesh net. I deployed a temperature-salinity probe and surface drifters to determine the origin of water and plankton drifting a fixed location on incoming versus. outgoing tides.