Effects Of Temperature, Salinity And Food On Survival And Ingestion Of Two Dominant Planktonic Copepods In Xiangshan Harbor

Several experiments were carried out to determine the effects of temperature, salinity and food on ingestion and survival of two dominant planktonic copepods, Centropages mcmurrichi and Sinocalanus tenellus in Xiangshan Harbor, Ningbo city, Zhejiang province.The results for ingestion of Centropages mcmurrichi are listed below: 1) Both filtering rates(F,ml·nd-1·-1) and grazing rates(G, cells·nd-1·-1) of C. mcmurrichi were significantly affected by different microalga and its concentrations (P<0.01), and furthermore, the ingestion rates(I, μgC·nd-1·-1) of C. mcmurrichi for Isochrysis galbana, Chaetoceros calcitrans, Heterogloen sp. and Chlorella sp. were 12.418 μgC·nd-1·-1, 9.824 μgC·nd-1·-1, 6.683 μgC·nd-1·-1 and 5.229 μgC·nd-1·-1, respectively. 2) The effects of culture temperature varing from 6℃ to 20℃ on F and G of C. mcmurrichi were not significant (P>0.05), but the significant differences were observed when salinities ranged from 13 to 34 (P<0.01), and the optimum salinity was 20. 3) The results also showed that effects of container volume and diurnal feeding rhythm in laboratory condition on F and G of C. mcmurrichi were not differently significant (P>0.05).The effects of some factors on filtering rates and grazing rates of S. tenellus fed with Isochrysis galbana were also studied. The experiment demonstrated that the effects of experimental temperatures, salinities, food concentrations and copepod densities on F and G were obviously different (P<0.01), and it was found by orthogonal test that G of S. tenellus reached the top values just as the experimental temperature, water specific gravity, food concentration and copepod density were 15 ·, 1.010-1.1014, 150 000 cells/ml and 0.25 ind/ml, respectively.The experiments on survival rates were also conducted to investigate the response of the two copepods to temperature, salinity and their interaction. The results indicated l)The survival temperature and salinity of C. mcmurrichi rangedfrom 1 ℃ to 20 ℃ and from 5.8 to 29.3, respectively, and their optimum temperature and salinity were 10℃ and 18.9, respectively. 2) For S. tenellus, the survival temperature (varied from 1℃ to 32℃), optimum temperature( 20 ℃), survival salinity (ranged from 0 to 29.3) and optimum salinity (12.4) were also observed. 3) The influences of temperature, salinity and their interaction, which in turn resulted in lower contributions to survival rate were significantly different (P<0.01). 4) The maximum tolerance of salinity or temperature could reach only when temperature or salinity of culture condition was close to that of habitat.