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Copper avoidance and mortality of juvenile brown trout (Salmo trutta) in tests with copper-sulfate-treated water from West Branch Reservoir, Putnam County, New York

Water-Resources Investigations Report 99-4237
Prepared in cooperation with the New York City Department of Environmental Protection
By:  and 
https://doi.org/10.3133/wri994237

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Abstract

Copper-avoidance tests and acute-toxicity (mortality) tests on hatchery-reared, young-of- the-year brown trout (salmo trutta) were conducted with water from West Branch Reservoir to assess the avoidance response to copper sulfate treatment, which is used occasionally by New York City Department of Environmental Protection to decrease phytoplankton populations in the reservoir. Avoidance-test results indicate that juvenile brown trout tend to avoid dissolved copper concentrations greater than about 55 μg/L (micrograms per liter), which is the approximate avoidance-response threshold. The mean net avoidance response of brown trout to dissolved copper concentrations of 70 and 100 μg/L, and possibly 80 μg/L, was significantly different (at α= 0.1) from the mean net avoidance response of fish to control (untreated) water and to treated water at most other tested concentrations. Mortality-test results indicate that the 96-hr median lethal concentration (LC50) of dissolved copper was 61.5 μg/L. All (100 percent) of the brown trout died at a dissolved copper concentration of 85 μg/L, many died at concentrations of 62 μg/L and 70 μg/L, and none died in the control waters (7 μg/L) or at concentrations of 10, 20, or 45 μg/L. The estimated concentration of dissolved copper that caused fish mortality (threshold) was 53.5 μg/L, virtually equivalent to the avoidance-response threshold.

Additional factors that could affect the copper-avoidance and mortality response of individual brown trout and their populations in West Branch Reservoir include seasonal variations in certain water-quality parameters, copper-treatment regimes, natural fish distributions during treatment, and increased tolerance due to acclimation. These warrant additional study before the findings from this study can be used to predict the effects that copper sulfate treatments have on resident fish populations in New York City reservoirs.

Suggested Citation

Baldigo, B.P. and Baudanza, T.P., 2001, Copper avoidance and mortality of juvenile brown trout (Salmo trutta) in tests with copper-sulfate-treated water from West Branch Reservoir, Putnam County, New York: U.S. Geological Survey Water-Resources Investigations Report 1999–4237, 25 p., https://pubs.er.usgs.gov/publication/wri994237.

Table of Contents

  • Abstract
  • Introduction
  • Study Methods
  • Avoidance Response and Mortality of Juvenile Brown Trout in Tests with Copper-Sulfate-Treated Water
  • Conclusions
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Copper avoidance and mortality of juvenile brown trout (Salmo trutta) in tests with copper-sulfate-treated water from West Branch Reservoir, Putnam County, New York
Series title Water-Resources Investigations Report
Series number 99-4237
DOI 10.3133/wri994237
Year Published 2001
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) New York Water Science Center
Description 25 p.
Country United States
State New York
County Putnam County
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details