Abstract

Benthic macroinvertebrates play a vital role in ecosystem functioning, such as nutrient cycling, primary production, decomposition and material translocation. A study was done to determine the functional feeding groups (FFGs) distribution along two streams of the Olifants River System, South Africa. There were longitudinal differences of the functional groups but were more pronounced in the Dwars River than in the Spekboom River. Collector-gatherers and collector-filterers were the most abundant groups recorded in both rivers. The least abundant groups were the shredders and scrapers in both rivers. The highest abundance of shredders in both rivers was at upstream sites (DS1 and SS1), more scrapers were found at midstream sites (DS3 and SS2), collector-gatherers and collector-filterers increased in the downstream (SS4) of the Spekboom River and predators were nearly constant in relative abundance at all sites. The relative abundance and richness of the FFGs did not conform completely to the river continuum concept (RCC). This could be related to the degradation of the catchment resulting from human activities which affected the quality of the water.

摘要

底栖大型无脊椎动物在生态系统功能（例如养分循环，初级生产，分解和物质移位）中起着至关重要的作用。进行了一项研究，以确定沿南非Olifants河系的两条河流的功能性饲喂组（FFG）的分布。各个官能团之间存在纵向差异，但在Dwars河中比在Spekboom河中更为明显。收集者和收集者和过滤者是两条河流中记录最丰富的群体。最少的群体是两条河流中的碎纸机和刮板机。两条河流中的碎纸机数量最多的是上游站点（DS1和SS1），在中游站点（DS3和SS2）发现了更多的刮刀，Spekboom河下游（SS4）的收集者-收集者和收集者-过滤者增加，并且在所有地点，捕食者的相对丰度几乎恒定。FFGs的相对丰度和丰富度并不完全符合河流连续统概念（RCC）。这可能与人类活动影响水质而导致流域退化有关。