Macroinvertebrate community structure along the longitudinal gradient of an agriculturally impacted stream
Macroinvertebrate community structure along the longitudinal gradient of an agriculturally impacted stream
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DOI：
10.1007/s002679900118
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发表时间：
1998-05-01
影响因子：
3.5
通讯作者：
Brusven, MA
中科院分区：
文献类型：
--
作者：
Delong, MD;Brusven, MA
Lapwai Creek 是爱达荷州北部受农业影响的一条溪流，在两年的时间内进行了季节性采样，以确定大型无脊椎动物群落组成是否沿纵向梯度发生变化，以及变化是否遵循河流连续体概念的预测。还研究了食物资源供应变化与社区结构之间可能存在的关系。使用 Hess 采样器在 Lapwai Creek 纵向梯度的八个位置采集底栖无脊椎动物。随机串分析表明，个体数量或功能性喂养组组成不存在纵向梯度。聚类分析显示，除了接收小型富营养化水库流出物的地点外，所有地点都具有相似的群落结构，进一步表明无脊椎动物群落组成沿着河流的纵向梯度保持一致。除水库以下的地点外，该群落在所有地点均以功能性食草动物为主。整个拉普瓦伊溪中的碎纸机很少见，即使在仍然保留健康河岸植被的地区也是如此。对流域内其他溪流的研究表明，在这些溪流的上游发现了许多物种；拉普瓦伊溪 (Lapwai Creek) 整个地区都没有出现对农业影响较低的地区。与大型无脊椎动物同时收集的数据表明，整个河流中颗粒有机物的输入、储存和运输较低，而附生生物丰度较高。尽管流经三个不同的地貌区域，但没有出现纵向变化，并且除了一个通过对优势类群和功能性摄食群体进行聚类分析得出的所有地点的分组表明，农业改变影响了拉普威溪的群落结构，导致能够承受农业面源污染的大型无脊椎动物的相对同质的组合。对这一假设的额外支持是一种食物来源——附生生物——的丰富度和少量的陆地有机物。前者的丰富和后者的稀有可归因于农业活动造成流域的改变，通过投入化肥产生高营养浓度，并清除河岸植被以清理更多的农业用地并提供更多的河流通道。
Lapwai Creek, an agriculturally impacted stream in northern Idaho, was sampled seasonally over a two-year period to determine if macroinvertebrate community composition changed along the longitudinal gradient and ii changes followed predictions of the river continuum concept. Possible relationships between changes in food resource availability and community structure were also examined. Benthic invertebrates were collected at eight locations along the longitudinal gradient of Lapwai Creek using a Hess sampler. Random skewer analysis suggested there was no longitudinal gradient for either number of individuals or functional feeding group composition. Cluster analysis revealed that all locations, excluding a site receiving outflow from a small, eutrophic reservoir, had a similar community structure, further suggesting that invertebrate community composition remained consistent along the longitudinal gradient of the stream. The community was dominated at all sites, excluding the site below the reservoir, by functional grazers. Shredders were rare throughout Lapwai Creek, even in areas where healthy riparian vegetation stili remained. Studies of other streams within the drainage basin show that many species found in the upper reaches of these streams; where agricultural impacts are low, were absent throughout the length of Lapwai Creek. Data collected concurrently with macroinvertebrates indicated that the input, storage, and transport of particulate organic matter was low throughout the stream, whereas periphyton abundance was high. The absence of longitudinal changes, despite flowing through three distinct geomorphological regions, and the grouping of ail sites except one by cluster analysis for both dominant taxa and functional feeding groups suggest that agricultural alteration has influenced community structure of Lapwai Creek, resulting in a relatively homogeneous assemblage of macroinvertebrates capable of tolerating agricultural nonpoint source pollution. Additional support for this hypothesis is the high abundance of one food source, periphyton, and the small quantities of terrestrially derived organic matter. The abundance of the former and the rarity of the latter can be attributed to alteration of the drainage basin resulting from agricultural activities through inputs of fertilizers that generated high nutrient concentrations and the removal of riparian vegetation to clear more land for agriculture and provide increase access to the stream.