Survival and molting of the pea crab larvae Tunicotheres moseri Rathbun 1918 (Brachyura, Pinnotheridae) exposed to copper

The acute lethal toxicity of copper, as well as its sublethal effect on mol ting, was studied on larval and postlarval stages of the pinnotherid crab T unicotheres moseri. The most sensitive stage was zoea I, presenting a signi ficant mortality above 0.5 mug . L-1. Abnormal setation of the maxillipeds was observed in zoeae II moulted from zoeae I exposed to 100 mug . L-1 and higher copper concentrations, causing a reduced swimming activity of the la rvae. This pathology could be reverted after molting of affected zoea II to megalopa, which would be the first report in crustacean larvae that states the possibility of reverting morphological abnormalities after molting. Fo r zoeae II and megalopae, the inhibition of molting and high mortality was registered at 1,000 mug . L-1. The effect of copper on the duration of the larval and postlarval stages was differential: It retarded the duration of the stage zoea I, did not modify that of zoea LT, and accelerated the ecdys is of the megalopae to first crab. However, precocious molting to megalopae was associated with a smaller body size at the concentration of 100 mug . L-1. This differential effect of copper on the larval stages throughout the larval development could be ecologically relevant. Because of their lecith otrophia, their short developmental period, their good survival in control conditions, and the high sensitivity showed to copper (especially zoea I), larvae of T. moseri have shown that they are an excellent model for studyin g the effect of pollutant on survival, molting rate, growth, and morphogene tic changes during development.