DIFFERENTIAL-EFFECTS OF ORGANIC AND INORGANIC MERCURY ON THE MICROPYLE OF THE EGGS OF FUNDULUS-HETEROCLITUS

The eggs of Fundulus heteroclitus from Piles Creek (PC), a polluted en vironment, were compared to those from a reference population from rel atively unpolluted waters on eastern Long Island (LI). We have shown i n a previous study that PC embryos had a higher resistance to meHg (me thylmercuric chloride) than LI embryos but not to Hg (inorganic mercur ic chloride). Twenty minute exposures of eggs prior to insemination li kewise showed PC eggs were more tolerant to 1.0 mg l-1 meHg but more s usceptible to 1.0 mg l-1 Hg and also remained viable in clean sea wate r for a longer time than LI eggs. Scanning electron microscopy reveale d that the reduced insemination success after egg exposure to meHg was due to artificial activation, due to rupture of cortical vesicles and blockage of the micropyle. On the other hand, inorganic mercury produ ced very different morphological effects. Eggs exposed to Hg showed a swelling of the micropylar lip and a decrease in its diameter, which m ay have led to the reduction in insemination.