Study of toxicological sensitivity of three aquatic organisms representing the three major groups of fresh water Zooplankton (Cladocera, Copepoda, Rotifera) to the insecticide Chlorpyrifos

Acute toxicity of the pesticide Chlorpyrifos tests were conducted to determine the Lethal concentration LC50 during 48 hours exposure on three species of fresh water Zooplankton: Brachionus calyciflorus ( Rotifera), Mesocyclops leuskarti (Copepoda) and Daphnia magna ( Cladocera). • It was found that the species Daphnia magna is the most sensitive to the pesticide Chlorpyrifos as the value of 48h-LC50=1.28 μg/L, followed by the species Mesocyclops leuskarti 48h-LC50=28 μg/L while it was observed severe lack of sensitivity of the species Brachionus calyciflorus to the pesticide 48h-LC50=910 μg/L. • Depending on the values of the units of toxicity TU has been shown that the toxicity of the pesticide Chlorpyrifos is from the fourth level = highly toxic (TU = 78.30) for Daphnia, and Level III = acute toxicity (TU = 3.57) for Mesocyclops, while it is the first level = non toxic (TU = 0.11) for Brachionus. • Each increase in the concentration of the pesticide 1.0μg/L lead to increase the mortality rate in the species studied about: Daphnia magna ، % 68.79 Mesocyclops leuskarti ، % 0.22 Brachionus calyciflorus % 0.0468 As a result, we can expect that the arrival of the pesticide to aquatic ecosystems will affect the whole bio-community in these ecosystems and the inter their relationships, which in turn could be the cause of the disruption of the ecological balance with vague consequences that are difficult to understand its dimensions.

Determination of NOECs for the Most Important Toxic Substances to the Rotifer, Brachionus Calyciflorus Using Electrophoresis Method

Sublethal toxicity studies were conducted with a rotifera (Brachionus calyciflorus) to determine the No observed effect concentrations (NOECs) of a different eight toxic substances based on the protein mass reduction. Protein mass (with moleculer weight 43KDa - 67KDa) was quantified using electrophoresis method. Quantitation of protein concentrations demonstrated that toxicant stress reduced protein concentrations. The NOECs-43KDa and NOECs - 67KDa were reported. Since in vivo protein cocentrations can be assessed in a short time, these results can be obtained in only a few hours, which is substantially less than traditional whole animal reproductive tests. NOECs - NOECs - 43KDa test were generally more sensitive end points than NOECs - NOECs-67KDa test and more sensitive than standard whole animal toxicity tests for only four toxicants.