Effects of carbaryl (SEVIN) on the state I zoeae of the red-jointed fiddler crab,Uca minax (LeConte)

Shortly after spawning, zoeae of the red-jointed fiddler crab,Uca minax, were exposed to 1.0, 0.5 and 0.1 mg l^?1 of the insecticide carbaryl. Exposed zoeae were observed for fatalities, changes in phototaxis, and altered swimming behavior. Fifty per cent mortalities in these concentrations occurred after 12.5, 14.5 and 25 h, respectively. Zoeae displayed a rapid loss of positive phototaxis, which occurred after 2, 4 and 16 h, respectively. Abnormal swimming behavior was observed in all exposed groups, with total cessation of swimming activity occurring in 6 hours in groups I and II and 16 hours in group III.