Distribution Feature Of The Main Environment Factors On Producing Area Of Meretrix Meretrix In Tidal Zone Shellfish

Researches on shellfish culture environment mainly comprised the microorganism in the environment, zoobenthos, sediment polluted and bioremediation, etc.. In this paper,based on the field investigations,laboratory detections and data processed during 2010,the concentrations,distributions and sources of the contaminantes were analysed,including the total bacteria,total coliforms,fecal coliforms and TPHs,in surface water,sediments,and clams from the tidal flat in Rudong,Jiangsu provice,where the clams cultured.At the same time,the level that the clam quality influenced by the environment quality and as well as the relationship between them were analysed in this paper. The results would provide some guidance to better monitoring the beach environment where the shellfish cultured and to improve the quality of clams,what's more,a scientific basis would be provided for the shellfish health and a sustainable beach aquaculture.The main results were as follows:(1)The range of total bacteria in the surface water,sediments and clams were respectively 1.0×102cells/ml～1.65×105cells/ml,1.0×102cells/g～4.51×105cells/g,1.40×102cells/g～1.00×107cells/g.The range of total coliforms in the surface water,sediments and clams were respectively ND～9.3×102cells/L,ND～2.3cells/g,ND～73.64cells/g.There were no significant regularity not only in the coliform quantity changes among the seasons,but also the changes among the stations in the surface water. There were few differences between total coliforms at different stations in the sediments,and the same phenomenon happened in clams.(2) The mean values of TPHs in surface waters were 0.033 mg/L,0.029 mg/L,0.053 mg/L and 0.054 mg/L respectively in winter, spring,summer, and autumn.In spring TPHs content was the lowest,and while that of autumn was the highest.There were some stations which were over the light level in each investigation,and what's more,the pollution degree was greater in summer and autumn than that in other seasons.The mean contents of TPHs in sediment were 72.92mg/kg,12.85mg/kg,257.89mg/kg and 31.94 mg/kg,and in summer the highest appeared,while the loweat appeared in spring,which may be caused by the different mechanical components of sediment. TPHs of sediments were all consistent with the first category national marine sediment quality standard.The mean contents of TPHs in the clams were 7.28mg/kg,21.87mg/kg,7.61mg/kg and 6.01 mg/kg respectively in winter,sping,summer and autumn.Based on evaluation by the single-factor pollution index method ,there were some seriously polluted stations in winter,spring and also in summer,and in autumn there were only part of the sites lightly polluted.(3) The size order of correlation between the total bacteria in clams and that in surface water was sping>winter>autumn>summer.The relationship between total coliforms in clams and that in the water was highly significant in summer , and that was significant in winter and autumn while it was not obvious in spring.And total bacteria in clams had obvious relationship with that in the sediments in winter(R=0.833,p=0.010),which had no obvious relationship between them in winter (R=0.237,p=0.209)and summer(R=0.836,p=0.164). Coliform bacteria in clams and in sediments in the summer had significant positive correlation (R= 0.853, p= 0.031), correlations in other seasons were not significant.At the same time,the correlation degree between total bacteria in clams and environment was lower than that of total coliforms. In the shellfish micro-ecological system,coliform bacteria may play an important part.(4) The relationship between TPHs in clams and that in the water was significant in winter, spring and summer,while it was not obvious in autumn.The relationship between that in the clams and sediments was obvious in winter,autumn and spring,yet was not significant in summer.The size order of correlation between the TPHs in clams and that in sediments was winter>autumn>sping>summer.The correlation between the TPHs in clams and sediments was more higher than that in clams and surface water,which indicated that the TPHs content in clams was subjected to TPHs content in sediments more influences.