An evaluation of the toxicity of potassium chloride, active compound in the molluscicide potash, on salmonid fish and their forage base

Open-File Report 2018-1080
Prepared in cooperation with the U.S. Fish and Wildlife Service
By: , and 

Links

Abstract

Potash, with the active ingredient potassium chloride (KCl) is a chemical that is currently being evaluated for potential use as a molluscicide to combat invasive zebra mussels and quagga mussels in Western United States waters. Although data available for other freshwater fishes indicate that recommended treatment levels of potash as a molluscicide are sublethal, this has not been demonstrated for all salmonid species. The objectives of this study were to perform toxicity testing to determine the lethality of potassium chloride against selected species of salmonid fish (brook trout and Chinook salmon) and selected invertebrate forage, and to identify any potential adverse physiological impacts of KCl to these salmonids in water at treatment levels used for mollusk eradication. Minimal mortality (n=1 fish) was observed during 96-hour toxicity testing at KCl concentrations of 0 to 800 milligrams per liter (mg/L), indicating that the lethal concentration (LC50) values in these salmonid species were considerably higher than realistic molluscicide treatment concentrations. Sublethal effects were examined through evaluation of behavioral and morphological (histological) observation as well as specific blood chemistry parameters (electrolytes, osmolality, glucose, and cortisol). There was no strong evidence of significant physiological impairment among the two salmonid species due to KCl exposure. Whereas statistically significant differences in some parameters were observed in association with KCl treatments, it is unlikely that these differences indicate adverse biological impacts. Acute toxicity tests were conducted with invertebrate species at KCl exposure concentrations of 0–3,200 mg/L. Daphniid exposure trials resulted in differences in mortality among the test groups with higher mortality evident among the higher KCl exposure concentrations with a calculated LC50 value of 196 mg/L KCl for a 48-hour exposure. Crayfish exposed to higher concentrations of KCl at or above 800 mg/L as specimens exhibited death or reversible paralysis. Chironomid larvae exposures were largely inconclusive because of cannibalistic behavior among the various test groups.

Suggested Citation

Densmore, C.L., Iwanowicz, L.R., Henderson, A.P., Blazer, V.S., Reed-Grimmett, B.M., and Sanders, L.R., 2018, An evaluation of the toxicity of potassium chloride, active compound in the molluscicide potash, on salmonid fish and their forage base: U.S. Geological Survey Open-File Report 2018–1080, 33 p., https://doi.org/10.3133/ofr20181080.

ISSN: 2331-1258 (online)

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Applied Methodology and Procedures
  • Results
  • Interpretations and Conclusions
  • Selected References
  • Appendix 1. Water Chemistry Analysis
  • Appendix 2. Ionized potassium measurements—96-hour acute toxicity tests
  • Appendix 3A. Water-quality measurements collected daily from all experimental tanks for the 96-hour potassium chloride toxicity test, with brook trout at high baseline water conductivity
  • Appendix 3B. Water-quality measurements collected daily from all experimental tanks for the 96-hour potassium chloride toxicity test with brook trout at low baseline water conductivity
  • Appendix 3C. Water-quality measurements collected daily from all experimental tanks for the 96-hour potassium chloride toxicity test with Chinook salmon at high baseline water conductivity
  • Appendix 3D. Water-quality measurements collected daily from all experimental tanks for the 96-hour potassium chloride toxicity test with Chinook salmon at low baseline water conductivity
  • Appendix 3E. Water-quality parameters for a 24-hour potassium chloride exposure evaluating physiological impacts on brook trout at high baseline water conductivity
  • Appendix 3F. Water-quality parameters for a 24-hour potassium chloride exposure evaluating physiological impacts on brook trout at low baseline water conductivity
  • Appendix 3G. Water-quality parameters for a 10-day potassium chloride exposure for the evaluation of physiological impacts on Chinook salmon
  • Appendix 4. Behavioral and morphological changes observed among acute toxicity tests for Chinook salmon and brook trout
  • Appendix 5. Histological changes noted among brook trout and Chinook salmon in the 96-hour acute toxicity testing
  • Appendix 6. Log probit analysis calculation of the potassium chloride lethal concentration concentrations for daphniid toxicity trials

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title An evaluation of the toxicity of potassium chloride, active compound in the molluscicide potash, on salmonid fish and their forage base
Series title Open-File Report
Series number 2018-1080
DOI 10.3133/ofr20181080
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Leetown Science Center
Description Report: viii, 33 p.; Data release
Online Only (Y/N) Y
Additional Online Files (Y/N) N