Determining the lethal concentration (LC50 96h) of butachlor herbicide for Acipenser persicus and Acipenser stellatus fingerlings

The toxic effects of the herbicide Butachlor were studied using a concentration of 0.4-1.3ppm and 0/1-1ppm on fingerlings of the Persian sturgeon, Acipenser persicus, and Stellatus sturgeon, Acipenser stellatus, respectively in 1999. We carried out six treatments with three replicates and used one control based on the static O.E.C. D. method. Over the experiments, pH ranged between 6.7 -8.2, total hardness was measured to be 230 mg/l, water temperature was 20 plus or minus 1 degrees centigrade and dissolved oxygen was above 6 mg/l. We found that the LC50 96h of the Butachlor on fingerlings of the Persian sturgeon, Acipenser persicus, and Stellatus sturgeon, Acipenser stellatus, weighing 1-3 grams was 0.44 and 0.07 mg/l respectively. Also assessed the LC10, LC50, LC90 of the herbicide on the fingerlings of the sturgeons using the Probit Analysis procedure. We determined the maximum allowable concentration of the Butachlor herbicide for the fingerlings of the Persian sturgeons, Acipenser persicus, and Stellatus sturgeons, Acipenser stellatus, to be 0.044 and 0.007 mg/l. Based on the standards, the herbicide is considered highly toxic for the studied fingerlings

Environmental factors affecting agar extraction from Gracilaria corticata in the coastal areas of Persian Gulf, Bandar-e-Lengeh

The effects of environmental factors and season on agar extraction from Gracilaria corticata were investigated for the period 1993-94 in the coastal areas of Persian Gulf. Water temperature, water salinity and ammonia and phosphate ions were measured monthly. Mean temperature was found to be 27.8 centigrade, mean salinity was 36.38 PPT., mean ammonia ions was 0.154mg/l and mean phosphate ions was 0.029mg/l . After harvesting, Gracilaria were dried and weighed and subjected to the alkali agar extraction method. Maximum and minimum agar yield were obtained in August and December with 10.01% and 5.44% respectively. There was a significant correlation between agar yield, biomass and ammonium fertility. Results showed that the maximum agar yield from Gracilaria was obtained in March and August