THE EFFECT OF LOW CONCENTRATIONS OF PHENOL AND AMMONIA ON EGG-PRODUCTION RATES, FECAL PELLET PRODUCTION AND EGG VIABILITY OF THE CALANOID COPEPOD ACARTIA-CLAUSI

Estimates of daily fecundity, hatching success and fecal pellet production are reported for Acartia clausi females exposed for 10 d to low levels of phenol and ammonia. Copepods were collected in 1991 and 1992 from a southern coastal area of the Mar Grande of Taranto (southern Italy). A reduction in egg numbers and fecal pellet production was observed for females after 8 d of exposure to 500 mu g l(-1) phenol concentration. Ammonia(120 mu g l(-1)) produced a significant increment in egg production, but hatching success was reduced by about 50% after nine exposure days. A, clausi was more sensitive to ammonia than phenol at high concentrations (24-h LC(50) phenol=32.26 mg l(-1); 24-h LC(50) ammonia=0.91 mg l(-1)). At low concentrations, only long-term exposure to phenol determined a reduction in fecundity.