太湖河蚬时空格局

Temporal and spatial patterns of Corbicula fluminea in Lake Taihu

2006年12月-2007年11月对太湖河蚬种群进行了周年逐月调查.河蚬在分布区的年均密度和生物量分别为265.7ind./m2和100.9g/m2,在夏、秋季均达到高值.根据壳长频数分布的周年变化,太湖河蚬一年一代,繁殖期主要在5-7月份.河蚬主要分布在贡湖湾、马迹山以南区域、西南湖区和小梅港沿岸区域.分析表明,太湖中河蚬的空间分布表现出明显的差异性,这种差异性受到多种因素的综合影响.在北部梅梁湾和竺山湾湖区湖泊中的低溶氧量是限制河蚬生长的最重要因素;在贡湖湾、马迹山以南湖区和西南部湖区,各种生境条件和底质性质适合河蚬的生长繁殖,其密度和生物量的最高值出现在贡湖湾的中心区域(820.0ind./m2,522.9g/m2);在东太湖湖区浮游植物密度较低,底质中有机质较少,食物来源是影响河蚬分布的较重要因素.

An annual investigation on Corbicula fluminea in Lake Taihu was carried out monthly from December 2006 to November 2007.The annual average density and biomass of C.fluminea were 265.7ind./m2 and 100.9g/m2,respectively.Both the density and biomass peaked during the summer.According to the annual dynamics of the frequency distributions of shell length,C.fluminea reproduced once a year,and mainly occurred during April-June.C.fluminea distributed mainly in the Gonghu Bay,the region south to Mt.Majishan,the southwest lake region and the littoral regions of the Xiaomei Port.The spatial distribution of C.fluminea showed great diverse,resulting from combined effects of multiple factors.In Meilang Bay and Zhushan Bay,oxygen concentration of lake water may be the most important factor limiting the growth of C.fluminea.In the Gonghu Bay,the region south to Mt.Majishan and the southwest lake region,various habitats including sediment properties are suitable for the growth and reproduction of C.fluminea.The highest density and biomass of C.fluminea were found in the central area of Gonghu Bay （820.0ind./m^2,522.9g/m^2）.In the east region of Lake Taihu,the density of phytoplankton and organic matter concentration in sediment are relative low.Therefore,in this region,food availability may be the main factor that limiting the distribution of C.fluminea.