论文部分内容阅读
The copepod Tigriopus japonicus has a wide geographical distribution and is regarded as a model species for marine ecotoxicology.Here,through a multigeneration life-cycle test,T.japonicus were exposed to different mercuric chloride(HgCl2)treatments(i.e.the nominal concentrations with 0,0.5,1,10 and 50 μg/L in the seawater respectively)for five successive generations(F0-F4),and subsequently all the treatments were recovered in clean environments for one generation(F5).Six life history traits,i.e.the survival,developmental time of nauplius phase,developmental time to maturation,fecundity,number of clutches,and number of nauplii/clutch,were investigated for each generation.Hg accumulation was also analyzed for the adult copepods in the generations of F1 and F3.The results show that the copepods fecundity and number of nauplii/clutch were significantly depressed by mercury exposure with a dose-dependent manner in F0-F4,and it could be attributable to Hg accumulation in the F1 and F3 generations which increased with the increasing metal concentrations.However,the other parameters were unaffected under most of the mercury treatments for F0-F4.Meanwhile,all the six life traits show no difference among all the treatments in the F5 generation,indicating that physiological acclimation may take place in Hg resistance obtained by marine copepods during the long-term metal exposure.Thus,environmental risk assessment of contaminants must therefore be based on a long-term multigenerational exposure to provide a realistic measurement of the impacts of pollutants on aquatic organisms.