珠江河口渔业生物稳定同位素营养级分析

Trophic spectrum of fishery species from the Pearl River Estuary by stable isotope analysis

于2015年8月采集珠江河口东、西口门水域39种主要渔获物(30种鱼类,5种虾类和4种贝类),分析其稳定碳、氮同位素组成(δ^(13)C、δ^(15)N)和营养级谱。结果表明:珠江口东口门水域主要渔业生物δ13C范围为-31.92‰^-19.34‰(均值-23.65‰),δ^(15)N值范围为9.57‰~17.14‰(均值13.48‰);西口门水域主要渔业生物δ^(13)C范围为-26.75‰^-16.36‰(均值-21.19‰),δ15N范围为9.01‰~16.49‰(均值12.72‰),两区域生物群落δ^(13)C和δ^(15)N均值差异显著(δ^(13)C:P<0.001,δ^(15)N:P=0.036);对东、西口门两水域主要渔业生物群落营养级采用不同的基线生物计算,发现两水域生物群落营养级范围相近,范围为2.0~4.7,包括植食性、杂食性、低级肉食性、中级肉食性和高级肉食性5个类群;其中,底、顶端营养级生物种类少,而中间层次种类多;与Fishbase数据库记录比较发现,约43%的种类营养级均值位于Fishbase营养级范围内,约33%低于Fishbase低阈值,余下的23%高于Fishbase高阈值。初步建立了珠江河口主要渔业生物营养级谱,可为当地渔业资源的利用和管理提供依据。

Totaling 39 major fishery species including 30 species of fish, 5 species of shrimps and 4 species of mollusks were collected in the Pearl River Estuary in August 2015. The stable carbon and nitrogen composition （δ13C and δ15N） of the organisms were analyzed using StableIsotope Ratio Mass Spectrometry. The results showed that fishery community in east and west parts of the Pearl River Estuary had statistically different stable isotopes values （δ13C： P〈0.001, δ15N：P=0.036）. The δ13C values of fishery community ranged from -31.92‰ to -19.34‰ （with an average of -23.65‰） in the east estuary and from -26.75‰ to -16.36‰ （with anaverage of -21.19‰） in the west estuary. The δ15N values of fishery community ranged from9.57‰ to17.14‰ （with an average of 13.48‰） in the east estuary and from 9.01‰ to 16.49‰ （with an average of 12.72‰） in the west estuary. Trophic levels of fishery organisms in the east and west estuary were calculated based on different baseline organisms; the trophic levels of communities in the two areas were similar, with a range of approximately 2.0 to 4.7, including herbivores, omnivorous, low, middle and high classes of carnivores. Among the organisms, a smallamount of species were at the bottom and top trophic positions, while large amount of species were at the medium trophic positions. The average trophic levels of about 43% of fish species were within the record ranges, 33% of fish species were lower than the low threshold, and 23% of fish species higher than the high threshold when compared with the trophic level of the same fish from the Fishbase. By preliminarily establishing trophic spectrum of primary fishery species in the Pearl River Estuary, this study provides a basis for utilization and management of the fishery resources in the study region.