马拉维Nyika高原三种溪流鱼类的生境类型(英文)

Habitat associations of three stream fishes on a montane plateau(Nyika Plateau, Malawi)

本研究调查了生活在非洲马拉维北部Nyika高原三种溪流鱼类的栖息地。分3个时期选择3条河流的24个地点进行取样,每个样点长100 m左右;分急流和回水湾两种生境类型作为独立的栖息地单元取样,据此观察研究对象和物理环境间的关系;用喜好指数和逻辑回归分析每种鱼重要栖息地是否稳定。瞻星平鳍鲇(Amphilius uranoscopus)通常喜欢生活在水深小于50 cm、流速0·4 -1 m/s的缓流河段,这里水色较深,河底多卵石。黄鱼(Labeobarbus johnstonii)常被发现在水深大于50 cm的河段,河水流速中等或较急。引入种虹鳟(Oncorhynchus mykiss)的活动范围常局限在水温低于20℃的河段,这些河段水深中等,流速较快,沿河多植物。虹鳟栖息地与土著种相似,可能与同域分布的土著种,特别是与广泛分布的瞻星平鳍鲇存在生存竞争。

This study examined the habitat associations of three stream fishes on a montane plateau, Nyika Plateau, in northern Malawi. Twenty-four sites were sampled over three different periods in three rivers of the plateau. At each site, a riffle and a pool were identified, in a stretch of about 100 m, as separate habitat units, and were sampled for fish and physical habitat. A preference index and logistic regression were used to determine the important habitat variables for each species. The mountain catfish Amphilius uranoscopus preferred shallow habitat （ 〈 50 cm） with coarse substrate （pebble and boulder） and moderate flow （0.4 - 1 m/s）. The yellow fish Labeobarbus johnstonii was associated with deep habitats （ 〉 50 cm） and moderate and fast flows. The distribution of the exotic trout Oncorhynchus mykiss was limited to low temperature （ 〈 20℃ ）. It was associated with moderate depth, fast flow and high abundance of riparian vegetation. The preferred habitat of trout overlapped with that of the indigenous species. Trout is likely, therefore, to have an impact on the indigenous species, especially the widespread mountain catfish, where they co-occur