ENERGETIC AND BEHAVIORAL-RESPONSES BY THE COMMON GOBY, POMATOSCHISTUS-MICROPS (KROYER), EXPOSED TO LINEAR ALKYLBENZENE SULFONATE

The acute toxicity of linear alkylbenzene sulfonate (LAS) on the commo n goby (Pomatoschistus microps), an estuarine fish, was established du ring a 96-h static exposure. The median lethal concentration was 2.6 /- 0.49 mg LAS/L (mean +/- 95% confidence limit). The acute behavioral responses to LAS at different concentrations were excess mucus secret ion and apathy at 1.0 mg/L; air gulping, distension of the mouth and o percula, change in pigmentation, and erratic swimming at 2.0 to 3.0 mg /L; and loss of balance and reactivity at greater than or equal to 4.0 mg/L. The frequency of operculum opening increased with increasing LA S concentrations and appeared at 4.0 mg/L, with a significant doubling in relation to the frequency observed in control fish (p = 0.025). Th e physiological responses by P. microps after prolonged exposure to su blethal and environmentally realistic concentrations of LAS (0.05-1.0 mg/L) were observed under semistatic conditions in the laboratory. Ing estion, respiration, and growth were also measured during 28 d of expo sure. A significant decrease in growth and respiration was found at 0. 1 mg LAS/L (p = 0.049 and 0.033, respectively), but ingestion was not affected. The effect concentrations for growth and respiration represe nt the lowest-observed-effect concentrations, which are both lower tha n values previously reported for fish. Gross conversion efficiency was affected negatively at 1.0 mg LAS/L (p = 0.001). Pomaroschistus micro ps is recommended as a suitable and relevant test organism for ecotoxi cological experiments.