珠江口海域双胞旋沟藻赤潮对卤虫幼体、鱼苗和虾苗的急性毒性

为研究2009年10月下旬在广东珠海海域爆发的双胞旋沟藻赤潮对养殖鱼类及水体中其它生物的影响,实验以卤虫幼体、金鼓鱼苗和凡纳滨对虾苗作为受试生物,在赤潮现场测试双胞旋沟藻对卤虫幼体、鱼苗和虾苗的急性毒性效应。结果显示,24 h双胞旋沟藻对卤虫幼体的LC₅₀(半致死浓度)为9.55×10⁴/mL,藻密度为2.5×10³/mL的双胞旋沟藻对卤虫幼体的LT₅₀(半致死时间)为48.5 h。60 h内该赤潮水体对鱼苗和虾苗的存活无不利影响,卤虫幼体和金鼓鱼苗均可摄食双胞旋沟藻,卤虫幼体对双胞旋沟藻的摄食率低。研究表明,双胞旋沟藻赤潮水体对卤虫幼体有一定的毒性作用,但在低藻密度条件下,卤虫幼体能以该藻为食并维持其生命,双胞旋沟藻对金鼓鱼苗和凡纳滨对虾苗无急性毒性作用。

Acute toxicity of Cochlodinium geminatum bloom waters from Pearl River Estuary on larvae of brine shrimp,fish and shrimp

Dinoflagellate genus Cochlodinium Schütt has been documented to form blooms along the coastlines of many countries and caused mass mortalities of fish or shellfish.From October to November,2009,harmful algal blooms(HABs)caused by dinoflagellate Cochlodinium geminatum broke out in the coastal waters in Zhuhai,Guangdong.The bloom covers more than 300 km².In order to understand the toxicity of the bloom water,and provide some basis to the algae bloom management and further study of this species,acute toxicity of the bloom water against larvae of zooplankton Artemia salina,fish Scatophagus argus and shrimp Penaeus vannamei was investigated under room conditions.Moreover,feeding rate of A.salina on C.geminatum was also investigated in this paper.The results showed that LC₅₀(Median Lethal Concentration)of C.geminatum against A.salina larvae was 9.55×10⁴/mL within 24 h.LT₅₀ of C.geminatum against A.salina larvae decreased with the increasing cell density.LT₅₀ of C.geminatum with cell density of 2.5×10³/mL against A.salina larvae was 48.5 h.No adverse effects of C.geminatum on the survival of fish and shrimp larvae was observed within 60 h.On the other hand,it was found that both A.salina and S.argus larvae could feed on C.geminatum.But the feeding rate of A.salina larvae was low.Overall,the bloom water of C.geminatum caused an impact on the survival of A.salina.C.geminatum with high cell density could cause mass mortality of A.salina larvae.However,A.salina could live on low cell densities of C.geminatum.Causes of the death of A.salina larvae may not be due to the ingestion of C.geminatum.C.geminatum caused acute toxicity neither against the S.argus larvae nor against the P.vannamei larvae.