基于稳定同位素方法的吕泗渔场近岸海域主要生物潜在碳源及营养级分析

The potential carbon source and trophic level analysis of main organisms in coastal water of Lüsi fishing ground,based on carbon and nitrogen stable isotope analysis

基于稳定同位素方法,对2018年吕泗渔场近岸海域夏季主要生物种类的潜在碳源及其营养级进行分析,利用IsoSource模型计算该海域消费者的3大碳源(浮游植物、悬浮颗粒有机物、底质有机物)贡献值,并比较叠加潜在碳源影响前后主要生物种类的营养级变化。结果表明,浮游植物和底质有机物对37种主要生物种类的贡献比例分别为58.7%和28.2%,而悬浮颗粒有机物的贡献较小。因此判定吕泗渔场近岸海域夏季主要生物种类的潜在碳源主要是浮游植物和底质有机物。通过分别叠加3大潜在碳源和单一物种作为基准值构建两个营养级谱,右营养级谱的生物种类营养级范围为1.74~3.92,比左营养级谱平均下降0.19个营养级,尽管两个营养级谱的整体趋势走向不变,但部分鱼类和多数虾类的营养位置发生改变。右营养级谱的基准值随着潜在碳源叠加比例的不同而变化,能有效反映生物营养级,更适用于低营养级的虾蟹类。但对于处于中高级消费者位置的鱼类来说,这种叠加的效果影响不大。

Trophic level among main organisms in costal water of Lüsi fishing ground in summer,2018,were analyzed in this study by stable isotope method.Using IsoSource model,we calculated potential carbon source contribution of the phytoplankton,POM and SOM of consumers,and then compared the former and latter TLs variation of main organisms by overlapping potential carbon source influence.Results showed that phytoplankton and SOM were main potential carbon source of main organisms in costal water of Lüsi fishing ground in summer.Two trophic level spectrums were constructed by overlapping three potential carbon sources and a single species as the baseline organisms,respectively.The trophic level of the right trophic level spectrum ranged from 1.74 to 3.92,which was averagely 0.19 lower than that of the left trophic level spectrum.Although the overall trend was unchanged,the trophic positions of some fish and most shrimps were changed in two spectrums.The baseline organisms in the right trophic level spectrum changed with the different stacking ratio of potential carbon sources,which could reflect the trophic level more effectively and was more suitable for organisms at low trophic levels,such as shrimp and crabs.However,this had little impact on fish in the position of middle and advanced consumers.