جستجوی مقالات مرتبط با کلیدواژه « دافنی ماگنا » در نشریات گروه « زیست شناسی »

Fenitrotione is one of the popular organophosphorus insecticides that is using in gardens and farms، which in this research the effects on mortality rate، filtration rate and intake in Daphnia magna، as an important zooplankton in aquatic ecosystems، was investigated. This organism has high feeding value for all fresh water fingerlings especially for marketing fish. Also the culturing of D. magna is one of the necessary purposes in fertilizing of rearing fish ponds. In this study، D. magna was used as indicator organism in ecotoxicological test. This study was done in static method for 24h، a design of 5 treatments (0. 005، 0. 01، 0. 02، 0. 04 and 0. 1) was arranged with three replicates. All water physico-chemical parameters such as temperature، pH، dissolved oxygen، hardness and electrical conduction were controlled. Chrorella volglaris (10 mg/l) was used to detect filtration rate and intake by D. magna and observed that with increasing Fenitrotione concentration، filtration rate and intake were decreased. According to the present research، Ec10 (Effective Concentration 10)، Ec50 (Effective Concentration 50) and Ec90 (Effective Concentration 90) were 0. 004 mg/l، 0. 011 mg/l and 0. 028 mg/l، respectively. Also maximum allowable concentration (MAC)، low observe effect concentration (LOEC) and none observe effect concentration (NOEC) were 0. 0011 mg/l، 0. 005 mg/l and 0. 00011 mg/l، respectively. It means that this insecticide is high toxic for D. magna. Hence we can conclude that Fenitrotione is very toxic for D. magna and the entered amount was more than EC10 in fresh water ecosystems، this phenomenon.

The Daphnia magna is a promising candidate for feeding freshwater fish larvae in cultural media. In this research، the effect of two Cyanophycae strain (Anabaena flosaquae and Oscillatoria africanum) on ingestion، filtration rate and feeding behavioral of Daphnia magna were investigated. Exposure was down at the same condition in three replications. Rate of filtration، ingestion and feeding of Daphnia magna from two investigated Cyanophycae strain were measured according to Gauld equation (1951). The results shown that with increasing of food concentration (Cyanophycae strains)، filtration، ingestion and feeding rate of Daphnia magna significantly decreased (P<0. 05). Maximum of these indices (798±60. 2، 70861± 992 and 0. 4±0. 02 respectively) in 3 mg/lit and minimum of mentioned parameters (100±17/7، 10683±492 and 0. 2±0. 01 respectively) were observed in 12 mg/lit. It means that Daphnia not able to filtered filamentous Cyanophycae makes some difficulty in filtration system of Daphnia، especially in high concentrations. The maximum of specific growth rate (SGR) (0. 5±0. 02) was observed in feeding with Anabaena flosaquae (in 4. 25 mg/l) (P<0. 05)، and survival rate of Daphnia magna not difference among mentioned algae (P>0. 05). According to the results can conclude that it is difficult to use Daphnia magna biological control of algal bloom in fresh water.