Effects of short-term exposure to xylenes on the early cleavage stages of cod eggs (Gadus morhuaL.)

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Abstract
Seawater solutions of the three isomers of xylenes were analysed both by gas chromatography (GLC) and ultra-violet spectroscopy (UV), and the two methods were compared. Cod eggs were exposed to seawater solutions of the xylenes. Concentrations ranged from less than 1 ppm to c. 35 ppm. Treatment during fertilization with ortho-xylene had no significant effect upon fertilization capacity, while meta-and para-xylene induced significant decreases in fertilization rate at concentrations above 10 ppm (p < 0.05). Fertilized cod eggs were exposed to xylenes 3 or 6 hours before the first cleavage. There was no significant difference in effect between the xylenes, and treatment for 3 and 6 hours gave similar effects. Effects upon the early cleavage pattern were significant from a concentration interval of 2–7 ppm (p < 0.01). Characteristic effects included inhibition of the formation, of the cleavage furrow. ‘Small cells’ or total absence of cleavage occurred in the highest concentrations (16–35 ppm), while in the concentration range 8–15 ppm, incomplete or uneven cleavage was usual. Exposure to lower concentrations could give a very wrinkled cleavage membrane.