| Recently, heavy metal pollution becomes more and more obvious in China."2001Report on the State of the Environment in China" indicated that reduction and control of heavy metal pollutionis one of the national major duties, and exceeding national standard of heavy metal Cu and Cd could still be found in inland fishery environmental different extents. The freshwater mueesl Anodonta woodiana belongs to the phylum of Mollusca, class of Bivalvia, order of Unionoida, family of Unionidae, and genus of Anodonta. It is a worldwide distributed species. A. woodiana has been used as a bioindicator for’Freshwater Mussel Watch’ research around the Taihu Lake of Chinato assess the contamination of organotins, organochlorines and heavy metals by our Key Laboratory of Ecological Environment and Resources of Inland Fisheries, the Chinese Academy of Fishery Sciences. Based on above pilot studies, our laboratory is further establishing an innovative "standardized A. woodiana" mussel population by artificial propagation techniques, which possesses the similar biometric characterization, genetic quality, and low background of environmental pollution. Moreover, the standardized mussels can be transplanted to field fishery waters to monitor the temporal and spatial dynamics of heavy metal pollution. This work is setting up a good foundation for establishment of a future large scale, standardization, and informatization "Standardized Freshwater Mussel Watch" system. The present study focus on the feasablilty of the transplantation monitoring and toxicity test of heavy metals by adult, and early life hisory individuals (e.g., glochidia and juveniles)"standardized A. woodiana", respectively, in order to understand the background of heavy metal pollution in the mussel transplanted waters, and tolerance, sensitivity the glochidia and juveniles to toxicity of heavy metals (especially Cu and Cd). Furthermore, the results of present study are hoped to be useful for future early warning of water metal pollution and conservation biology of the endangered, rare, and commecial freshwater mussles. The main results were summarized as follows:1.The living "standardized A. woodiana" mussels from the same artificially propagated and cultured population were divided into two groups. One of them was transplanted by cage into Donghu Lake (Wuhan City, Hubei Province) as the transplantation group. Another one was still kept by the same cage in Nanquan Aquatic Base as the culture group. The mussels were recaptured from the two groups per3months to determine Mn, Fe, Ba, Zn, Al, Mo, As, Tl, Cu, Cd, Ni, Pb, and Crconcentrations and their varations in total soft tissues by an Agilent ICP-MS7500ce. The mussels from the two groups generally presented a similar concentration order for the metals. The highest concentration was found in Mn, while the the lowest concentration was found in Cr. The remaining metals presented in the moderate concentrations. Even though, slight differeces could still be documented in some certain metals (e.g., Cu, Cd) between the transplantation and culture groups. There was a temporal influence to the metal bioaccumulation in the mussels. It is noteworthy that an increase tendency of Pb concentration could be observed in the transplantation mussels of the Donghu Lake. All the aforementioned results suggest that the approach of transplantation of "standardized A. woodiana" has a potential for untalization to understand the heavy metal background and dynamics in field aquatic environments.2. The glochidia of "standardized A. woodiana" were used to conduct the toxicity tests of heavy metal Cu and Cd in this study. The results showed that24-h to48-h Median effective concentrations (EC50s) for the glochidia were60.1and1.908μg/L for Cu, and22.23and4.587μg/L for Cd, respectively. The limit levels of Cu and Cd levels set by the National Standards for Fishery Water Quality (GB11607-89) are10μg/L and5μg/L. However, when48-h exposed to these concentrations, the survival rates of the glochidia were only44%and52%for Cu and Cd, respectively. Therefore, the limit levels of Cu and Cd of GB11607-89will not effectively protect the mussles at the glochidial stage of life historyof A. woodiana, and probably, other similar freshwater bivalvial mollusks.3. The juveniles of "standardized A. woodiana" were also used to conduct the toxicity tests of heavy metal Cu and Cd in the present study. The results showed that24-h,48-h to72h EC50s for the glochidia were27.218μg/L,8.54μg/L and7.18μg/L for Cu, and5.271μg/L,1.702μg/L and4.587μg/L for Cd, respectively. When48-h, and72-h exposed to the aforementioned regulatory limit levels of Cu and Cd in GB11607-89, the survival rates of the juveniles were only60%for Cu and65%and20%for Cd, respectively. Therefore, the limit levels of Cu and Cd of GB11607-89will also not effectively protect the mussles at the juvenile stage of life history of A. woodiana, and probably, other similar freshwater bivalvial mollusks. |
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