Acute Toxicity of Copper to Three Species of Pacific Salmon Fry in Water with Low Hardness and Low Dissolved Organic Carbon

Drew E Porter; Jeffrey M Morris; Michelle P Trifari; Matthew J Wooller; Peter A H Westley; Kristen B Gorman; Benjamin D Barst

doi:10.1002/etc.5724

Acute Toxicity of Copper to Three Species of Pacific Salmon Fry in Water with Low Hardness and Low Dissolved Organic Carbon

Environ Toxicol Chem. 2023 Nov;42(11):2440-2452. doi: 10.1002/etc.5724. Epub 2023 Aug 28.

Authors

Drew E Porter^{1

2}, Jeffrey M Morris³, Michelle P Trifari^{1

2}, Matthew J Wooller^{1

2

4}, Peter A H Westley¹, Kristen B Gorman¹, Benjamin D Barst²

Affiliations

¹ College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, USA.
² Water and Environment Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska, USA.
³ Abt Associates, Boulder, Colorado, USA.
⁴ Alaska Stable Isotope Facility, University of Alaska Fairbanks, Fairbanks, Alaska, USA.

PMID: 37493065
DOI: 10.1002/etc.5724

Abstract

Proposed development of a mine within Alaska's Bristol Bay watershed (USA) has raised concerns about the potential impact of copper (Cu) on Pacific salmon (Oncorhynchus spp.). We conducted 96-h flow-through bioassays using low-hardness and low dissolved organic carbon water to determine the acute lethal toxicity of Cu to sockeye (Oncorhynchus nerka), Chinook (Oncorhynchus tshawytscha), and coho salmon (Oncorhynchus kisutch) fry. We aimed to determine Cu toxicity under field-relevant water quality conditions and to assess three methods of calculating ambient Cu criteria: the biotic ligand model (BLM), a multiple linear regression model endorsed by the US Environmental Protection Agency, and the hardness-based model currently used by the State of Alaska. The criteria generated by all models were below 20% lethal Cu concentrations by factors ranging from 2.2 to 54.3, indicating that all criteria would be protective against mortality. The multiple linear regression-based criteria were the most conservative and were comparable to BLM-based criteria. The median lethal concentrations (LC50s) for sockeye, Chinook, and coho were 35.2, 23.9, and 6.3 µg Cu/L, respectively. We also used the BLM to predict LC50s for each species. Model predictions differed from empirical LC50s by factors of 0.7 for sockeye and Chinook salmon, and 1.1 for coho salmon. These differences fell within the acceptable range of ±2, indicating the model's accuracy. We calculated critical lethal Cu accumulation values for each species to account for differing water chemistry in each bioassay; the present study revealed that coho salmon were most sensitive to Cu, followed by sockeye and Chinook salmon. Our findings underscore the importance of considering site- and species-specific factors when modeling Cu toxicity. The empirical data we present may enhance Cu risk assessments for Pacific salmon. Environ Toxicol Chem 2023;42:2440-2452. © 2023 SETAC.

Keywords: Bioavailability; Copper; Dissolved organic matter; Fish; Metals; Water quality criteria.

MeSH terms

Animals
Copper / toxicity
Dissolved Organic Matter
Hardness
Oncorhynchus*
Salmon
Water Pollutants, Chemical* / toxicity

Substances

Dissolved Organic Matter
Copper
Water Pollutants, Chemical