藻种、贝类密度和大小对背角无齿蚌和河蚬摄食率的影响

Effects of algal species, shellfish body size and density on the feeding rates of Anodonta woodiana and Corbicula fluminea

在水温为(20±1)℃的室内实验条件下,研究铜绿微囊藻(Microcystis aeruginosa)、小球藻(Chlorella pyrenoidosa)、斜生栅藻(Scenedesmus obliquus)3种藻类和贝类规格(身体大小)及密度对背角无齿蚌(Anodonta woodiana)和河蚬(Corbicula fluminea)摄食率的影响。三因素方差分析表明:藻种对背角无齿蚌的摄食率无显著影响,但显著影响河蚬的摄食率;贝类密度和规格均显著影响2种贝类的摄食率,两者对背角无齿蚌摄食率有交互作用;但对河蚬无交互作用;2种贝类摄食率均随着密度的增加而下降,大规格背角无齿蚌和2种较低密度下的大规格河蚬的摄食率均分别显著小于小规格,但在2种较高密度下的河蚬摄食率在规格间无显著差异;2种贝类摄食率与水体溶解氧均显著正相关,但相关性河蚬明显高于背角无齿蚌;不同藻类的投喂对溶解氧不产生显著影响,但贝类大小和密度显著影响溶解氧。结果表明,溶解氧胁迫程度会影响身体大小和密度对2种贝类摄食率的交互作用,小规格河蚬对低溶解氧的耐受性低于大规格。

In laboratory, Anodonta woodiana(AW)and Corbicula fluminea(CF)were fed with 3 algal species of Microcystis aeruginosa, Chlorella pyrenoidosa and Scenedesmus obliquus, and the effects of algal specie, shellfish body size and density on the feeding rates were studied at approximately 20 ℃ of water temperature. Three-way analysis of variance(ANOVA) showed that: There was significant difference among three algae in feeding rate for CF but was not for AW;Shellfish body size and density had effects on feeding rate of them;Interaction of body size and density on feeding rate for CF was found, however not observed for AW;The feeding rate of the two shellfishes both decreased significantly with increasing density;The feeding rates of the small-sized individuals were significantly higher than those of large-sized ones for CF reared at 2 relatively low densities and for AW at all three densities;No significant differences in feeding rate were found for CF reared at 2 relatively high densities;The correlation between feeding rate and dissolved oxygen(DO) concentration for CF was obviously higher than that for AW;Shellfish body size and density rather than feeding with different algae influenced the DO in water container. The results showed that the stress degree by low DO might cause the differences between the two shellfishes in interaction of body size and density on their feeding rate and the large-sized individuals of CF are more tolerant of low DO than the small-sized ones.