Effect of food availability on the acute toxicity of four chemicals to mysidopsis bahia (mysidacea) in static exposures

Abstract

The effect of nutritionally deficient Artemia nauplii on the growth of the mysid, Mysidopsis bahia, were evaluated in static systems. When Artemia nauplii with or without highly unsaturated fatty acid 20:5 ω 3 were fed to 24‒h‒old M. bahia there was no difference in growth of mysids on either ration after 96 h of feeding. A study comparing amount of available food in static systems necessary for good survival and growth indicated that rations of 5, 10 or 30 Artemia per mysid per day (A/m/d) were different from 50, 70, 90 and 110 A/m/d as measured by dry weight. Static acute 96‒h tests were conducted with ≤24‒h‒old Mysidopsis bahia using either carbophenothion, cypermethrin, malathion, or 4‒(tert‒octyl)phenol. For each chemical, two replicate tests were conducted simultaneously with each of three rations of food provided. The rations chosen were 10 A/m/d, providing survival with minimal growth, a midpoint ration (60 A/m/d), and 110 A/m/d, clearly in excess of that necessary for good survival and growth. Only LC50s obtained in tests using 10 A/m/d were significantly different from other test results. These tests indicate that lack of food does adversely affect results of mysid static tests. In addition, excess food has the potential to reduce dissolved oxygen to nearly unacceptable concentrations.