* TOXICITY OF SOIL DISPERSING AGENTS DETERMINED IN A CIRCULATING AQUARIUM SYSTEM

Abstract

ABSTRACT The toxicity of two non-ionic oil-dispersing agents was determined on a number of marine species: the edible mussel Mytilis edulis, winter flounder, soft shell clam, mummichog, Atlantic silversides and fourth stage lobster larvae. The bioassay system used consisted of a series of storage reservoirs and exposure tanks with a total volume of 112 liters. Water movement was provided by a series of marine aquarium pumps which circulated water at a rate of 4 liters/min. Additional aeration was not required for the mummichog, mussel or fourth stage lobster larvae. At 20°C, TL 50's calculated from 24 to 96 hours fell between 30 and 75 mg/1, with no significant difference in toxicity between the two dispersants. At 5°C, toxicity in the mummichog was significantly lower; this may be explained by the accompanying higher oxygen levels. The advantages of the circulating aquarium system in relation to the static and continuous-flow bioassay systems are discussed.