Robinson, Dwight E.; Henry, C.; Mansingh, Ajai
Author Affiliation, Ana.
Department of Life Sciences
Toxicity, bioaccumulation and tissue partitioning of dieldrin by the shrimp, macrobrachium faustinum de sassure, in fresh and brackish waters of Jamaica
Date of Publication
The 2-week no observed effect (NOEC) and lowest observed effect (LOEC) concentrations of dieldrin were determined for macrobrachium faustinum de sasure in fresh and brackish waters. LOEC 1, 10, 50, 95 values in fresh water were 0.001, 0.003, 0.011 and 0.058 µg 1-1, respectively, and in brackish water, 0.00006, 0.00027, 0.00165, and 0.0172 µg 1-1, respectively. The 96-hr LC10, LC50 and LC95 values were 0.029, 0.123 and 0.771 µg 1-1, respectively. It is proposed that NOEC and LOEC be redefined to take into account the percentage of individuals affected, the severity of symptoms and the recovery of poisoned individuals. Two new terms are proposed - Median Observable Effect Concentration (MOEC) for pronounced toxic symptoms in most individuals but mortality in <50%, and Pronounced Observed Effect Concentration (POEC), which inflicts mortality in >50% individuals. Bioaccumulation of dieldrin by M. faustinum from surrounding fresh and brackish waters were rapid and fairly uniform for the first 48 h when the bioconcentration equilibrium (14.4 ± 0.42 ng g-1 at 0.001 µg 1-1 and 42.5 ± 1.72 ng g-1 at 0.01jg 1-1) was achieved. Relative partitioning of residues (ng g-1 wet wt.), after 24 h exposure to 0.001 µg 1-1 of dieldrin in fresh water, in the different tissues was hepatopancreas > gonads > gills > large claws > muscle and exoskeleton. Shrimp which had accumulated 10.5 ± 0.52 ng g-1 dieldrin in fresh and brackish water, eliminated only about 52% of the residues after eight days in uncontaminated water.....