Predation on meiobenthic assemblages: resource use of a tanypod guild (Chironomidae, Diptera) in a gravel stream
Predation on meiobenthic assemblages: resource use of a tanypod guild (Chironomidae, Diptera) in a gravel stream
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对小型底栖动物组合的捕食：砾石流中长脚类群（摇蚊科、双翅目）的资源利用
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
J. M. Schmid
中科院分区：
文献类型：
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作者：
P. Schmid;J. M. Schmid
1.三个捕食摇蚊物种构成的数量8.8%（± 95%CL 2.2）的大型和小型底栖生物群落在沉积物表面和在潜流区的Oberer Seebach，砾石流在下奥地利州。Thienemannimyia geijskesi（Goetghebuer）和Nilotanypus pallidus（Meigen）的幼虫在10和40厘米之间的沉积物深度发生在较高的密度，而Conchapelopia pallidula（Meigen）在沉积物表面达到较高的密度。这三个物种在一年内完成了一代。
2.通过消化道分析共鉴定出97种食物种类和龄期，其中底栖轮虫41种，占总个体数的69.5%;摇蚊23种，占总个体数的22.9%。这三个tanypod物种表现出的转变，主要是轮虫种类在早期龄期的摇蚊和不同的其他小型和大型底栖动物类群在后期龄期。而不是转向更大的猎物大小，成长的捕食者扩大了他们的上限大小阈值，并继续包括较小的猎物物种在他们的饮食。在何种程度上tanypod龄期喂养类似的猎物大小类下降，增加幼虫的大小。结果表明，棕足类捕食量占总猎物密度的2.2%（± 95% CL 0.1），平均每头棕足类捕食1.32头（bootstrap 95% CL 1.26-1.39）。
3.微生境流的偏好不同的捕食物种和猎物组合。猎物密度和T. geijskesi和C. pallidula在水塘区的含量最高，而N.在浅滩地区，黑鲷的密度很高。
4. Tanypod幼虫之间的猎物类型的非选择性喂养。为了测试所观察到的大小（龄期）特定的空间和饮食重叠值之间的tanypod物种的意义，模拟产生的随机模型对内和种间协会的个人和群体的猎物和捕食者物种。在这些斑块中，食饵类型和高比例（P > 0.60）的捕食个体的食饵种群和个体几乎随机地被食饵种群和食饵个体的食饵种群和个体准随机选择。褐足虫龄对没有表现出持续的营养资源分配的时间，从而降低了在这个捕食者公会的食物竞争相互作用的程度。空间分离和非分离的tanypod龄期形成随机聚集在不同的流微生境彼此独立。
5.物种丰富的猎物组合，如底栖轮虫和幼虫摇蚊类的概率增加了非选择性喂养后，广泛的猎物物种的tanypods。猎物的选择是由猎物的可用性和tanypod个人喂养的许多物种，而甚至比例相互独立。
1. Three predatory chironomid species constituted numerically 8.8% (± 95% CL 2.2) of the macro- and meiobenthic community at the sediment surface and in the hyporheic zone of Oberer Seebach, a gravel stream in Lower Austria. Larvae of Thienemannimyia geijskesi (Goetghebuer) and Nilotanypus dubius (Meigen) occurred in higher densities in sediment depths between 10 and 40 cm, whereas Conchapelopia pallidula (Meigen) achieved higher densities at the sediment surface. The three species completed one generation in a year.
2. A total of ninety-seven prey species and instars were identified by gut analyses, of which forty-one benthic rotifer species constituted 69.5% of individuals and twenty-three chironomid species and their instars, 22.9%. The three tanypod species showed shifts from mainly rotifer species in early instars to chironomids and diverse other meio- and macrofaunal taxa in later instars. Rather than shifting towards larger prey sizes, growing predators expanded their upper size thresholds and continued to include smaller prey species in their diet. The extent to which tanypod instars fed on similar prey size classes declined with increasing larval size. Predation by tanypods amounted to 2.2% (± 95% CL 0.1) of the combined prey densities and prey consumption averaged 1.32 (bootstrap 95% CL 1.26–1.39) individuals per predator individual.
3. Preferences for microhabitat flow differed between predator species and in the prey assemblage. Prey densities and densities of T. geijskesi and C. pallidula were highest in pool areas, whereas N. dubius achieved high densities in riffle sites.
4. Tanypod larvae fed non-selectively among prey types. To test the significance of observed size(instar)-specific spatial and dietary overlap values amongst tanypod species, simulations were generated from random models for pairs of intra- and interspecific associations of individuals and groups of prey and predator species. Groups and individuals of tanypod instars fed near randomly on groups of prey types and a high proportion (P > 0.60) of prey individuals are quasi-randomly chosen by tanypods in those patches. Tanypod instar-pairs did not show a sustained trophic resource partitioning in time, thus reducing the degree of competitive interactions for food in this predator guild. Spatially segregated and non-segregated tanypod instars formed random aggregations independent of each other at different flow microhabitats.
5. Species-rich prey assemblages such as benthic rotifers and larval chironomids increased the probability of non-selective feeding upon a wide spectrum of prey species by tanypods. Prey choice was governed by prey availability and tanypod individuals fed on many species at rather even proportions independent of each other.