PM14 Pesticides in Pacific Northwest (USA) Watersheds
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(PM213) Toxicity of Herbicides Komeen® and Sonar® to Crayfish, Snail, and Delta Smelt.

Huang, Z.C.1, Trumbo, J1, Finlayson, B1, 1 California Department of Fish and Game, Office of Spill Prevention and Response, Sacramento, CA, USA

ABSTRACT- We determined the acute toxicity of aquatic herbicides Komeen® and Sonar® to larval stage of crayfish (Procambarus clarkii), snail (Physa species), and delta smelt (Hypomesus transpacificus). Komeen® (ethylenediamine complex of copper) and Sonar® (fluoridone) are registered in the United States and California for the control of aquatic weeds. In laboratory water (hardness = 133 mg/L CaCO3) and natural "site" water (hardness = 125 mg/L CaCO3), the acute toxicity (96-h LC50 values) of Komeen® to crayfish ranged from 31,833 to 53,545 g/L (as Cu) and to snail ranged from 327 to 641 g/L (as Cu), respectively. Komeen® to delta smelt produced 96-h LC50 values of 24,400 g/L and 14,995 g/L (as Cu) in Sacramento River water (hardness = 86 mg/L CaCO3) and San Joaquin River water (hardness = 66 mg/L CaCO3), respectively. Compared to the tests with Ceriodaphnia dubia and fathead minnow, crayfish, snail, and delta smelt are less sensitive to Komeen®. Environmental levels of Komeen® (500 to 1000 g Cu/L) used in aquatic weed control programs have no direct impact to crayfish and delta smelt but may be lethal to aquatic snails. In laboratory water (hardness = 133 mg/L CaCO3), the acute toxicity (96-h LC50 values) of Sonar® to crayfish was 105,940 g/L (as fluoridone) and to snail 130,853 g/L (as fluoridone), respectively. These values are higher than maximum concentration by the Sonar® product label (150 g/L as fluoridone). Impacts to crayfish and snail would not expected from the application of Sonar®. Our results suggest that Komeen® and Sonar® would be the herbicides that can be used with reasonable environmental safety toward native fauna.

Key words: crayfish, fish, Toxicity, snail

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