Acute Toxicity of Ammonia to Larval Penaeus Japonicus
摘要
Chlorination to eliminate fouling organisms in the cooling system of acoastal power plant may cause undesirable effect on milkfish(Chanos chanos)larvae in the nearby fry collecting area.This study was to find out the effectof residual chlorine on the mortality of milkfish larvae under various temperatureand salinity regimes.Milkfish larvae of two stages,namely 8(H8)and17(H17)days after hatching were exposed to combinations of five chlorineconcentrations(0.924 to 1.596 mg/l)at three temperatures(26°to 34℃)andthree salinities(26 to 34 ppt)for one hour.Up to second order multipleregression models were constructed to evaluate and compare the resistance ofmilkfish to chlorine at both stages under environment of various chlorineat both stages under environmentment of various chlorine concentration(C),temperature(T),and salinity(S).The resulted optimal models were:Sin^(-1)M^(1/2)=-1.3501+2.7089×10^(-2)×S×C+2.7612×10^(-2)×T×CSin^(-1)M^(1/2)=-1.7616+3.7605×10^(-2)×S×T+4.3621×10^(-2)×T×Cfor H8 and H17 stage,respectively.From these models the average one hourLC(subscript 50)s(mg/l)were 1.3092 and 1.7112 for H8 and H17,respectively.For bothstages,mortality increased with chlorine concentration.Both temperatureand salinity had synergistic effect on chlorine toxicity for H8 stage.Onlytemperature had synergistic effect on chlorine toxicity for H17 stage.Duringthe milkfish larva collecting season,chlorine concentration of the effluentfrom power plant should be kept below 0.066-0.085 mg/l to avoid the impacton milkfish larvae.