Protein, nucleic acid and adenylate levels in Daphnia magna during chronic exposure to chlordecone

The relationships between levels of several biomolecules and survival and reproduction were investigated in Daphnia magna exposed for 21 days to chlordecone concentrations ranging from zero to 60 μg litre⁻¹. Biomolecules, which included total protein, ribonucleic acid, deoxyribonucleic acid, adenosine diphosphate and adenosine triphosphate, were monitored on days 7 and 21. The highest no observable effect concentration (NOEC) based on survival and reproduction was 11·2 μg litre⁻¹ chlordecone. Although the level of each biomolecule per individual daphnid was decreased in a concentration-dependent manner by exposure to chlordecone, protein was most sensitive and had the same NOEC as survival and reproduction. The relative sensitivity of these three parameters when expressed as percent of control was survival > reproduction > protein. RNA/DNA and ADP/ATP ratios were not significantly affected by chlordecone exposure; however, ratios of protein/RNA/DNA and ATP/DNA were significantly increased in daphnia exposed to 48·4 μg litre⁻¹ chlordecone.