[Toxicity evaluation of malathion, carbaryle and glyphosate in common carp fingerlings [Cyprinus carpio, linnaeus, 1758]]

Common carp [Cyprinus carpio] fishes during release into the rivers estuary of the Caspian southern basin are generally exposed to a broad spectrum of agricultural pesticides. The objective of this study was to investigate the effects of three agricultural pesticides including Malathion, Carbaryle and Glyphosate on C. carpio in lethal level by determining LC[50] 96h and sub-lethal levels via cholinesterase [ChE] activity. The median lethal concentration using a standard method which is called OECD No. 203 [1992], was measured. About 300 fingerlings with average weight of 2.0 +/- 0.4 g were randomly selected and were then exposed to each pesticide in three treatments [0.1, 0.2 LC[50] 96h and negative control] in three replications. 5, 10 and 15 days after the test period, sampling from the head and body of fishes was carried out. The ChE activity was assayed with biochemical method described by Ellman. The LC[50] 96h for three glyphosate, malathion and carbaryle pesticides were obtained as 6.75, 1.3 and 12.67 mg/L, respectively. The mean values of ChE for both head and body under control conditions were found 1241.356 and 723.103 mU/min/mg protein, respectively. Therefore, the ChE activity of head was 1.7 times more than the body. During the test period, inhibition activitiy of ChE was significantly observed in the fishes treated by any of three components in comparison with control [p<0.05]. The ChE inhibition potential by carbaryle and glyphosate was lower than malathion as compared with control. The exposure time concentration exhibited a significant effect compared to the fishes treated by the investigated pesticide types. The used pesticide concentrations for non-target species which were ineffective and permissible according to the lethality bioassay test can lead to their enzyme responses and bio-damages

Effect of Temperature on post ovulated oocyte quality maintenance in female rainbow trou, oncorhynchus mykiss

Effect of temperature on the duration of post ovulated oocyte quality maintenance in abdominal cavity of female rainbow trout, Oncorhynchus mykiss, was assessed to determine suitable time of stripping. Egg quality measurement was done through assessing the eying and hatching rates of eggs. Regarding the best temperature range reported for salmonid brood fish in breeding season [3-10 C] the study was undertaken in two temperatures of 2 +/- 0.5 C and 8 +/- 0.5 C. In each of the noted temperatures, 15 female brood fish were used as 15 replicates and stripped 5 times. Time interval of each two spawnings was 7 days. Results indicated that temperature has a significant effect on the suitable time of stripping. When the temperature increased from 2 C to 8 C, the optimum eyeing and hatching rates were transferred from second week to the first one. Also, eyeing rate was decreased from 83% for the fifth treatment at 2 C to 3.6% at 8 C. The same trend was observed for the hatching rates. The decrease of post ovulatory suitable stripping time from 30 days in 2 C to two weeks in 8 C, shows the role of temperature on egg quality maintenance and confirms that the increase of water temperature in optimal living range, shortens the suitable post ovulatory time of stripping. This time duration estimated at least 21 DPO at 2 C and 14 DPO at 8 C. Also the time needed for overripening of the eggs estimated more than 224 Degree-Days. So the time duration of post ovulated oocyte quality maintenance in abdominal cavity of female rainbow trout is highly dependent on water temperature