Crustacean Zooplankton Was Studied In Five ponds In AL- Sinn's
Fish farm. As a one Of The Most Important components Fresh
Water Ecosystem . The samples of zooplankton were collected
During Period From November 2013 To March 2015, By One
Sampling a Month.
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.
Zooplankton samples were collected seasonally from three stations in the south of
Al-Hammar Marshes southern Iraq during the period from January to December 2011, by
Plankton net of a mouth aperture of 40 cm and a mesh-size 0.90 mm mounted with a f
low
meter in the mouth. The results showed that the population density of Cladocera ranged
between 79 ind/m3 during winter at station 1 (Al-Mas-hab) and 41971 ind/m3 during spring
at station 2 (Hareer). Density of Cladocera was positively correlated with water
temperature and to a lesser extent with salinity. About 13 species of Cladocera belonging
to 11 genera were recorded at three stations. The high values of diversity were recorded in
winter at all stations (1.68, 1.16, and 1.68 respectively) while the lowest values were
recorded during spring at all stations (0.06, 0.03, and 0.01 respectively).
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.