克氏原螯虾两种养殖模式的食物网结构及其食性比较

FEEDING HABITS OF PROCAMBARUS CLARKIA AND FOOD WEB STRUCTURE IN TWO DIFFERENT AQUACULTURE SYSTEMS

为比较克氏原螯虾(Procambarus clarkii)精养模式和稻虾共作模式下的食物网结构及其食性差异,对两种养殖模式的基础食源与消费者的δ13C和δ15N进行了分析,并借助SIBER考察了各自的食物网结构,定量计算不同饵料对克氏原螯虾食物的贡献率。结果显示:在采集的19种样品中,消费者的δ13C值介于–34.22‰—–25.34‰,δ15N值介于2.33‰—8.05‰,营养级介于1.46—3.64;在精养模式下克氏原螯虾的营养级(2.34)高于共作模式(1.79)。食物网结构参数对比表明,两种模式下克氏原螯虾的生态空间利用率接近,但共作模式的食物网营养结构多样性较高,群落的营养生态位范围较宽,食物网的营养冗余程度较低,不同物种竞争激烈程度较低;食性分析显示,在两种模式下克氏原螯虾的δ15N值与其体长、体重具有线性正相关关系,说明克氏原螯虾营养级随着其体型增大而提高,另外克氏原螯虾在两种养殖模式中均偏向于摄食动物性饵料,共作模式中克氏原螯虾饵料来源分布较精养模式更均匀,其植物性饵料贡献率较精养模式更高。研究表明:精养模式的物质能量从基础食源传至克氏原螯虾的传递损耗较共作模式要高;与精养模式相比,稻虾共作模式中克氏原螯虾更偏向植食性。

In order to explore the food composition of Procambarus clarkia and the food web structure in two different systems(crayfish-only system and integrated rice-crayfish symbiosis farming(IRCSF)system),we analyzed carbon and nitrogen stable isotope ratios(δ13C andδ15N)of sources and consumers,food web structure by SIBER and the food composition of P.clarkia by SIAR.The results showed that among the 19 collected species,theδ13C value of the consumer was between–34.22‰to–25.34‰,theδ15N value was between 2.33‰to 8.05‰,and the trophic level was between 1.46 to 3.64.The trophic level of P.clarkia in crayfish-only system was higher than that in IRCSF system.The metrics of food web reflected that the isotope niches in two systems using P.clarkia were similar.In IRCSF system,the trophic diversity in the food web was higher than that in crayfish-only system,and the niche overlap of each species and trophic redundancy in food web were lower than those in crayfish-only system.The significant positive correlation between the body length/weight andδ15N value of P.clarkia mean that P.clarkia prefer animal baits in two systems.The food contribution for P.clarkia was uniform and the proportion of plant baits was higher in IRCSF system compared with the crayfish-only system.The results indicated that the transfer loss of energy from sources to P.clarkia is higher in crayfish-only system,and the P.clarkia in IRCSF system was more herbivorous.