The Interactive Effects of Watershed Condition and Contaminant Biotransport by Introduced Pacific Salmon on the Contaminant Load of Stream- Resident Fish in Great Lakes Basin Tributaries

EPA Grant Number: F13F11071
Title: The Interactive Effects of Watershed Condition and Contaminant Biotransport by Introduced Pacific Salmon on the Contaminant Load of Stream- Resident Fish in Great Lakes Basin Tributaries
Investigators: Gerig, Brandon Scott
Institution: University of Notre Dame
EPA Project Officer: Lee, Sonja
Project Period: August 16, 2014 through August 16, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Fellowship - Aquatic Ecology and Ecosystems , Academic Fellowships

Objective:

This study will evaluate the effects of watershed condition and contaminant biotransport by introduced Pacific salmon on the contaminant load of stream- resident fish in GLB tributaries. The objective is to establish an environmental framework to predict the influence of Pacific salmon spawners on the contaminant load of stream-resident fish (e.g., brook trout) in GLB tributaries. The Great Lakes fishery is especially sensitive to impacts on tributaries, because many fish species use those areas as spawning and rearing habitat and thus represent an indelible ecosystem linkage between the lakes and their tributaries. These fish can transfer effects from lakes to tributaries in ways that are contrary to the normal paradigm of downstream transport of organisms and material.

Approach:

This research will combine field surveys, manipulative experiments and modeling to better understand the relationship between salmon spawners and contaminant levels in stream-resident fish, as well as the role of other factors (such as instream characteristics and watershed condition) in mitigating this relationship. A suite of predictive models will evaluate the influence of watershed and in-stream covariates on stream-resident contaminant levels. This project will also quantify the food web structure in streams affected by salmon runs, using stable isotope analyses to determine the mechanism by which contaminants are transported to fish. Third, analysis of stream food web structure in natural streams will be coupled with manipulative experiments at the Hunt Creek Fisheries Research Station. Using experimental stream reaches, salmon contaminant transfer to stream-resident fish will be directly assessed, while controlling for natural variation. Last, existing ecosystem and bioenergetics models will be used to predict how resident fish populations will respond to varying levels of contaminants, salmon spawner abundance and watershed management. Models will probe complex relationships in stream ecosystems to assess how contaminants are incorporated within the food web and ultimately affect fish.

Expected Results:

The influence of salmon spawners on the contaminant load of stream-resident fish is expected to be most pronounced where (1) salmon-mediated transport of contaminants is highest and (2) background contaminant levels are minimal because of watershed and instream characteristics. Previous research suggests that introduced salmon spawners deliver contaminants to streams through their eggs and carcasses, as indicated by elevated contaminant loads in stream-resident fish from stream reaches supporting salmon runs.

Potential to Further Environmental/Human Health Protection

This research is critically important to assessing the effect of both non-native species (e.g., Pacific salmon) and contaminants (e.g., PCBs, mercury) on stream ecosystems in the GLB. It will assess the ecological benefits and costs of salmon management in the GLB, so that fisheries managers can pursue strategies that mitigate the costs associated with introducing non-native species that bioaccumulate contaminants. This research will also identify areas for salmon stocking where the risks of contaminant biotransport can be minimized. Additionally, it could assist with developing local consumption advisories for sport fish caught in watersheds with high contaminant loads. Local consumption advisories are especially important to underprivileged communities that rely on subsistence harvest of fishery resources to meet their dietary needs.

Supplemental Keywords:

contaminants, ecosystem assessment and modeling, Pacific salmon

Progress and Final Reports:

  • 2015
  • Final