RESPONSE OF MUSSEL BRACHIDONTES STRIATULUS TO CHLORINATION - AN EXPERIMENTAL-STUDY

Though the brackish-water mussel, Brachidontes striatulus (Hanley) (sy n. Modiolus str iatulzrs) is an important fouling animal in power stat ion cooling circuits, there are no published studies on the tolerance of this species to chlorination. Mortality pattern as well as physiolo gical behaviour (byssus thread production, foot activity index and fil tration rate) of three different size groups (7, 18 and 25 mm shell le ngth) of B. striatulus, were studied at different chlorine concentrati ons (0-5 mg l(-1)). At 1 mg l(-1) chlorine residual, 7 mm size group m ussels showed 100% mortality in 468 h (20 days) and 25 mm size group m ussels in 570 h (24 days). At relatively high levels of chlorine resid uals (5 mg l(-1)), 100% mortality in 7 and 25 mm size groups took 102 and 156 h, respectively. The exposure time to chlorine required for 10 0% mortality of B. striatulus is much lower than that reported for som e other common fouling mussels. Chlorine concentration significantly a ffected the mean time of death for all size groups of mussels. All siz e groups showed progressive reduction in physiological activities such as filtration rate, foot activity index and byssus thread production when chlorine residuals were increased from 0 to 1.5 mg l(-1). Reducti on in physiological activities of mussels was strongly correlated with the concentration of chlorine. (C) 1997 Elsevier Science B.V.