The effects of 2 coexisting crayfish on an Appalachian river community
The effects of 2 coexisting crayfish on an Appalachian river community
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两种小龙虾共存对阿巴拉契亚河流群落的影响
DOI：
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发表时间：
2005
影响因子：
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通讯作者：
R. Creed
中科院分区：
文献类型：
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作者：
B. Helms;R. Creed
摘要小龙虾在小河流中具有关键物种和生态系统工程师的作用，但在大河流中的作用还不清楚。两种小龙虾，Orconectes cristavarius和Cambarus chasmodactylus，共存于北卡罗来纳州西部的新河南叉。我们使用肠道内容物分析和围隔实验，调查这两种小龙虾对沉积物积累和底栖无脊椎动物的影响。小龙虾内脏主要含有沉积物和植物碎屑。然而，C.裂趾蛙肠中的碎屑和动物性物质含量显著高于裂趾蛙; cristavarius guts和O. cristavarius肠道比C.裂趾龙内脏在现场实验中，沉积物体积较低，在开放的篮子和笼控制，这是暴露于小龙虾和底栖动物喂养的鱼类，比在外壳只包含小龙虾。沉积物量最高的鱼类/小龙虾围栏。尽管它们对沉积物积累的影响，小龙虾并没有显着影响的任何无脊椎动物tax. No明确的摇蚊密度和围封处理之间的关系，但摇蚊密度与沉积物体积呈正相关。小龙虾围隔中的豆娘（Calopteryxmaculata）比开放处理和笼内对照中的数量更多，而剑水蚤桡足类在O。cristavarius enclosure比C. chasmodactylus enclosures. 2种螯虾的饮食中的显着差异与其对无脊椎动物的影响差异无关。我们的研究结果表明，这2种小龙虾可能是功能冗余在这个社区，尽管饮食的差异。此外，小龙虾对无脊椎动物类群没有明显的影响，这表明小龙虾在大河中的影响可能不如在小溪中那么强烈。
Abstract Crayfish can act as keystone species and ecosystem engineers in small streams, but their effects in large rivers are not well known. Two species of crayfish, Orconectes cristavarius and Cambarus chasmodactylus, coexist in the South Fork of the New River in western North Carolina. We used gut-content analyses and an enclosure–exclosure experiment to investigate the influence of both species of crayfish on sediment accumulation and benthic invertebrates. Crayfish guts contained mostly sediment and vegetative detritus. However, C. chasmodactylus guts contained significantly more detritus and animal matter than O. cristavarius guts, and O. cristavarius guts contained significantly more sediment than C. chasmodactylus guts. In the field experiment, sediment volume was lower in open baskets and cage controls, which were exposed to crayfish and benthic-feeding fish, than in enclosures containing only crayfish. Sediment volume was highest in fish/crayfish exclosures. Despite their effect on sediment accumulation, crayfish did not significantly affect the density of any invertebrate taxon. No clear relationship was found between chironomid density and enclosure–exclosure treatment, but chironomid density was positively correlated with sediment volume. Damselflies (Calopteryx maculata) tended to be more abundant in crayfish enclosures than in open treatments and cage controls, and cyclopoid copepods tended to be more abundant in O. cristavarius enclosures than C. chasmodactylus enclosures. The significant differences in the diets of the 2 species of crayfish were not associated with differences in their effects on invertebrates. Our results suggest that these 2 species of crayfish may be functionally redundant in this community, despite differences in diet. Furthermore, the lack of pronounced crayfish effects on invertebrate taxa suggests that the effects of crayfish may not be as strong in large rivers as in small streams.