利用放射性碳和稳定性碳同位素技术估算抚仙湖北部近岸湖区消费者的碳源贡献

Assessing carbon sources and their contributions to consumers in northern Lake Fuxian using radiocarbon and stable carbon isotope techniques

碳同位素技术可用于辨析湖泊消费者的食物来源。基于抚仙湖北部近岸湖区主要消费者及其各食物来源的放射性同位素特征(Δ^(14)C)与稳定同位素特征(δ^(13)C),运用IsoSource混合同位素模型估算了不同碳源对湖泊消费者的贡献。抚仙湖各食物来源浮游植物、沉水植物和陆源碎屑的δ^(13)C比值分别为-31‰、-13.5‰和-29.4‰,Δ^(14)C比值分别为101.5‰、42.9‰和19.8‰.两种消费者舌状叶镖水蚤和太湖新银鱼的δ^(13)C比值分别为-27‰和-23.5‰,而Δ^(14)C比值分别为52‰和44.2‰,表明抚仙湖的消费者依赖于现代碳的初级生产。IsoSource混合同位素模型估算结果显示:抚仙湖浮游植物对浮游动物和鱼类的贡献比例分别为34.7%和19.6%,沉水植物贡献为16.4%和36.4%,陆源碎屑为48.9%和44%,表明浮游动物的碳源主要是湖泊浮游植物与陆源碎屑,而鱼类的碳源则主要以沉水植物和陆源碎屑为主。

Carbon isotopes can be used to identify food sources for aquatic consumers.Based on the signatures of radiocarbon isotopes(Δ^(14)C)and stable carbon isotopes(δ^(13)C)of select consumers and their food sources in northern Lake Fuxian,the contribution of different carbon sources to these consumers was estimated using IsoSource modeling.The averageδ^(13)C value of phytoplankton,submerged plants and terrestrial detritus,the major food sources for consumers in Lake Fuxian,was-31‰,-13.5‰and-29.4‰,and theΔ^(14)C value was 101.5‰,42.9‰and 19.8‰,respectively.The averageδ^(13)C value of Phyllodiaptomus tunguidus and Neosalanx taihuensis,two major consumers of Lake Fuxian,was-27‰and-23.5‰,while theΔ^(14)C value of them was 52‰and 44.2‰,respectively,indicating that the consumers in Lake Fuxian relied on primary production derived from modern carbon.The results of IsoSource modeling revealed that the contribution of phytoplankton to zooplankton and fish in Lake Fuxian was 34.7%and 19.6%,respectively.The contribution from submerged plants was 16.4%and 36.4%,and the contribution from terrestrial detritus was 48.9%and 44%,respectively.These findings indicated that the major carbon sources of zooplankton in Lake Fuxian were phytoplankton and terrestrial detritus,while those of fish were submerged plants and terrestrial detritus.