基于稳定碳同位素技术的养殖贝类碳源分析

Carbon source analysis of bivalve-culture based on stable carbon isotope technique

贝类养殖作为碳汇渔业存在一定疑义,为了更好地解释贝类的碳汇功能并明确其碳源,应用稳定碳同位素技术对3种养殖贝类的碳源进行了分析。研究结果表明:3种养殖贝类的贝壳δ13C值介于-6.9‰^-6.3‰,软体组织δ13C值介于-23.2‰^-21.9‰,贝壳与软体组织δ13C的富集程度表现出负相关关系。3种养殖贝类的贝壳主要碳源为海水中的溶解无机碳(DIC),其次为溶解有机碳(DOC),两者合计贡献率在86%以上。3种贝类软体组织的主要碳源为悬浮物,其次为沉积物,两者合计贡献率在94%以上。贝壳与软体组织在碳源选择上具有极显著的差异性(P<0.01)。沉积物即泥沙不是贝壳碳的主要来源,转化成贝壳的碳绝大多数来自于海水的DIC,这使得海水中的DIC浓度下降,从而促进大气中CO2向水体转移,起到了间接固碳的作用,因此贝类养殖具有明显的渔业碳汇功能。

Shellfish culture as a part of carbon sink fishery is doubtful. In order to explain the carbon sink function and identify the carbon source of shellfish,the carbon sources of three culture-bivalve were analyzed by using stable carbon isotope technique. The results showed that： the δ13 C of the three culture-bivalve shells ranged from-6. 9‰ to-6. 3‰,the δ13 C of soft tissue ranged from-23. 2‰ to-21. 9‰,and the enrichment degree of δ13 C for shell and soft tissue was negatively correlated. The main carbon source of three culture-bivalve shells was dissolved inorganic carbon（ DIC）,followed by dissolved organic carbon（ DOC）,and the total contribution rate was above 86%. The major carbon source of soft tissue in three culture-bivalve was suspended solids,followed by sediments,with the total contribution rate of more than 94%. The shell and soft tissue of culture-bivalve showed extremely significant different selection in carbon source. Sediment was not the main source of carbon in culture-bivalve shells,most of the carbon converted into shells comes from the seawater DIC,which reduced the concentration of DIC in seawater,and promoted the CO2 in the atmosphere transfer to seawater. This plays a role of indirect carbon fixation. Shellfish aquaculture fishery has obvious function of carbon sequestration.