Effect of diatom lipid composition on the toxicity of trichlorobenzene. II. Long-term effects of 1,2,3-trichlorobenzene

Abstract

Exposures of four diatoms, Cyclotella meneghiniana, Melosira italica, Melosira varians , and Synedra filiformis to 0.3 ppm 1,2,3-trichlorobenzene were initiated at the 8th and 11th hours of the light period on a 16:8 h L/D cycle at 20°C. Cell counts, lipid content, and lipid class composition were monitored for 10 days. Melosira italica demonstrated the most long-term effects. Cell counts and chlorophyll a were greatly reduced on the 10th day when exposure was initiated in the 11 th hour of the light period in S. filiformis and in the 8th hour of the light period in M. varians . The data demonstrate that more immediate effects occur when exposures are initiated during periods of high polar lipid content or when polar lipids are being synthesized. Long-term effects are observed when exposure initiation occurs during periods of high neutral lipid content and higher total extractable lipid. The results suggest that the response of diatoms to low levels of chlorinated benzenes is related to normal variation in diel lipid composition. These results are repeatable, they vary with species, and exposures initiated at different times of the day may produce quite different results.