崇明东滩南部大弹涂鱼食源的稳定同位素分析

利用稳定同位素技术,对崇明东滩南部湿地4、5月份采集到的大弹涂鱼(Boleophthalmus pectinirostris)的食源进行初步研究。结果显示,大弹涂鱼δ13C和δ15N值分别为-19.28‰~-14.59‰,7.96‰~10.13‰。利用同位素混合模型(Iso Source)计算包括白茅(Imperata cylindrical)、芦苇(Phragmites australis)、互花米草(Spartina alterniflora)、糙叶苔草(Carex scabrifolia)、底栖微藻、颗粒有机物和沉积质在内的7种初级生产者对大弹涂鱼碳源食源贡献的可能范围及分布频率,结果表明白茅、芦苇、互花米草、糙叶苔草、底栖微藻、颗粒有机物和沉积质对大弹涂鱼食源的可能贡献范围分别为0%~69%、0%~30%、0%~72%、0%~30%、0%~76%、0%~44%和0%~47%。利用后整合方法计算得到C_3植物(芦苇和糙叶苔草)、藻类及有机质(底栖微藻、颗粒有机物和沉积质)和C4植物(白茅和互花米草)三大类生产者对大弹涂鱼食源的贡献情况,结果表明C_3植物、藻类及有机质和C_4植物对大弹涂鱼春季食物贡献范围分别为0%~30%、0%~76%和24%~72%,中值分别为15%、38%和48%,表明C_4植物是大弹涂鱼不可缺少的食源。同时,根据大弹涂鱼的δ15N值,得出大弹涂鱼属于2.07~2.65级营养级,为次级消费者。

Stable isotope analysis of food source of Boleophthalmus pectinirostriscollected from the south of Chongming Dongtan saltmarsh

The food sources of Boleophthalmus pectinirostris collected from the south of Chongming Dongtan saltmarsh in April and May were analyzed with the stable isotope technique.The results showed that δ13C and δ15N range values of B.pectinirostris were from-19.28 ‰ to-14.59 ‰ and 7.96 ‰ to 10.13 ‰, respectively.IsoSource software was used to calculate the frequency and range of potential carbon source contribution (0 % to 100 %) from seven food sources, including Imperata cylindrical, Phragmites australis, Spartina alterniflora, Carex scabrifolia, benthic microalgae, particulate organic matter and sediment organic matter to Boleophthalmus pectinirostris.Analysis results indicated that the potential contribution ranges of Imperata cylindrical, Phragmites australis, Spartina alterniflora, Carex scabrifolia, benthic microalgae, particulate organic matter and sediment organic matter were 0 %-69 %, 0 %-30 %, 0 %-72 %, 0 %-30 %, 0 %-76 %, 0 %-44 %, and 0 %-47 %, respectively.Then, contributions of the primary producers with similar isotope values was pooled and the method of posteriori aggregation was used to obtain the potential contribution ranges of 3 groups (C3 plants, algae and organic matter, and C4 plants).Analysis results of posteriori aggregation indicated that the potential contribution rate of C3 plants (P.australis and C.scabrifolia),algae and organic matter (benthic microalgae, particulate organic matter and sediment organic matter), and C4 plants (I.cylindrical and S.alterniflora) were 0 %-30 %, 0 %-76 %, and 24 %-72 %, respectively, with the corresponding median values of 15 %, 38 %, and 48 %.Posteriori aggregation indicated that the possible contribution rate of C3 plants (P.australis and C.scabrifolia),algae and organic matter (benthic microalgae, particulate organic matter and sediment organic matter), and C4 plants (I.cylindrical and S.alterniflora) were 0-30%, 0-76%, and 24-72%, respectively, with the corresponding median values of 15%, 38%, and 48%.These findings suggested C4 plants constituted a larger fraction of their carbon source than C3 plants, and the C4 plants were an indispensable food source of B.pectinirostris located on the south of Chongming Dongtan saltmarsh.In addition, the B.pectinirostris was concluded to belong to the 2.07-2.65 trophic level based on the δ15N values of B.pectinirostris, suggesting that B.pectinirostris was subconsumer in the food chain of the ecosystem.