 6/10 Very Good --- www.springerlink.com http://www.springerlink.com/content/1573-5117/?sortorder=asc&export=rss
Wednesday, July 23, 2008 --- 46 days ago http://www.springerlink.com/content/85378753342p4177/
| Abstract This study investigated the impact of introduced rainbow trout, Oncorhynchus mykiss , on the distribution and feeding of mountain catfish, Amphilius uranoscopus , on the Nyika Plateau, Malawi. Twenty-four sites were sampled over three different periods in three rivers. Fish habitat units were identified as separate riffle or pool, about 100 m in length, at each site. Each habitat unit was sampled for fish, invertebrates and physical habitat characteristics. Twenty four and 20 habitat units were sampled, respectively, from sites with catfish and sites with trout and catfish. In the absence of trout, the mountain catfish was associated with all depth ranges, with strong preference to shallow and moderate depth, and moderate to fast flow on coarse substratum type (gravel, pebble and boulder). In the presence of trout, the catfish was frequently associated with very shallow depth and slow flow. In its natural habitat, the catfish fed randomly, but preferred the most abundant invertebrate taxa, especially black fly larvae (Simuliidae). In the presence of trout, the catfish preferred mostly the chironomids. The preference by catfish for Simuliidae, also preferred by trout, was less in the trout streams than in its natural habitat. The prey taxa in the catfish stream were diverse, and consisted of large invertebrate predators. Trout streams were dominated by few prey taxa, especially black flies and chironomids. The catfish of the ... |
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