长江中下游浅水湖泊5种常见底栖动物碳、氮、磷化学计量特征

研究长江中下游地区浅水湖泊5种常见大型底栖动物(铜锈环棱螺、河蚬、苏氏尾鳃蚓、摇蚊属幼虫及中国长足摇蚊)碳、氮、磷化学计量特征,样品采集于多个不同营养水平湖泊.底栖动物碳、氮、磷元素含量的变化范围分别为31.6%~60.7%、5.2%~12.1%及0.41%~2.28%,碳氮比、碳磷比和氮磷比的变化范围分别为4.4~8.9、55~314及9.9~40.1,其中磷元素含量变化最大并是导致N∶P变化的主要原因.不同种类底栖动物元素组成具有显著差异,碳、氮、磷最高平均值分别出现在河蚬(48.4%)、苏氏尾鳃蚓(10.4%)及河蚬(1.09%).铜锈环棱螺(除氮磷比)和河蚬元素组成在不同营养水平湖泊间具有显著差异,重富营养湖泊太湖氮和磷含量最高.相关分析发现铜锈环棱螺及河蚬磷含量和氮磷比与营养状态指数显著相关,表明铜锈环棱螺和河蚬的碳、氮、磷化学计量特征并非保持严格的动态平衡.

C:N:P stoichiometry of five common macrozoobenthic taxa in shallow lakes along the Yangtze River

C:N:P elemental composition were measured in five macrozoobenthic taxa (Bellamya aeruginosa, Corbicula fluminea, Branchiura sowerbyi, Chironomus spp.and Tanypus chinensis) from several shallow lakes with contrasting trophic state. The tissue contents of carbon (C), nitrogen (N) and phosphorous (P) ranged from 31.6%-60.7%, 5.2%-12.1%, 0.41%-2.28%, respectively. The ratios of C:N,C:P and N:P ranged from 4.4-8.9, 55-314, 9.9-40.1, respectively. The most variable component was P content and accounted for 63.2% of the variation in N:P ratio. Elemental composition differed significantly among macrozoobenthic taxa, with C. fluminea showed the highest mean values of C (48.4%) and P (1.09), and B. sowerbyi presented the highest mean values of N (10.4%). Elemental composition of B. aeruginosa (except for N:P)and C. fluminea differed significantly among contrasting trophic state lakes, with the highest values of N and P were observed in a hypertrophic lake (Lake Taihu). P content and N:P ratio of B. aeruginosa and C. fluminea showed significant correlations with trophic state index (TSI), indicating that these two species deviated from strict homeostasis with respect to C:N:P stoichiometry.