扁担塘虾类群落组成、空间分布和生物量估算

SPECIES COMPOSITION,SPATIAL DISTRIBUTION AND BIOMASS OF SHRIMP COMMUNITY IN THE BIANDANTANG LAKE

2002年秋季,利用“蹦网”(Popnet)采样,调查了扁担塘的虾类组成、空间分布和生物量,以期为虾类资源的合理开发利用提供科学依据。采集样点31个,共采集到虾类44287尾,由6种组成,其中长臂虾科4种,匙指虾科2种。优势种是细足米虾(CaridinaniloticgracilipesdeMan)、日本沼虾(MacrobrachiumnipponensedeHaan)和中华新米虾(NeocaridinadenticulatesinensisKubo),它们占采样总数量的99.3%。根据水深特征将扁担塘划分为浅水区(<1.0m)、中等水深区(1.0—1.5m)和深水区(>1.5m);根据水生植被的分布格局将全湖划分四种生境类型:苦草生境、聚草生境、金鱼藻生境和裸地生境。协方差分析的结果表明:水深类型对虾类的分布没有显著影响,生境类型是决定虾类密度分布的主要因素。整个湖区虾类密度为83.36ind/m2,生物量为3.97g/m2。其中细足米虾的密度和生物量分别为64.69ind/m2,1.53g/m2;日本沼虾为8.99ind/m2,2.09g/m2;中华新米虾为8.61ind/m2,0.22g/m2。

The species composition,spatial distribution and biomass of shrimps in the Biandantang Lake,Hubei province,were investigated by sampling with pop-net(10m^2)in the Autumn of 2002. The total of 44 287 individuals belonging to 6 species,5 genera and 2 families,were collected from the 31 sampling sites. The dominant species were Macrobrachium nipponense,Caridina nilotic gracilipes and Neocaridina denticulate sinensis,which contributed 99. 3%to the total. In terms of water depth,the lake was classified into 3 water-depth areas:shallow area(<1.0m),medium-depth area(1.0—1.5m)and deep area(>1.5m). Based on the type and cover of aquatic vegetation,the lake was categorized into 4 habitat types: Vallisnerria spiralis habitat, Ceratophyllum demersum habitat,Myriophyllum spicatum habitat,and naked habitat. For dominant shrimps,significant difference in density was not observed among 3 water-depth areas(ANCOV,P>0.05);whereas,it was found among 4 habitat types(ANCOV, P<0.01). Each of the dominant species preferred the Vallisnerria spiralis habitat. The density and the biomass of all shrimps in the lake were estimated to be 83.36 ind/m^2 and 3.97 g/m^2,respectively,of which C. nilotic gracilipes contributed 64.69 ind/m^2 and 1.53 g/m^2,M. nipponense 8.99 ind/m^2 and 2.09 g/m^2,and N. denticulate sinensis 8.61 ind/m^2 and 0.22 g/m^2.