High altitude mountain streams as a possible refuge habitat for the catfish <Emphasis Type="Italic">Amphilius uranoscopus</Emphasis> |
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Authors: | Matthias P van Oosterhout Gerard van der Velde Ian G Gaigher |
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Institution: | 1.Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research,Radboud University Nijmegen,Nijmegen,The Netherlands;2.National Museum of Natural History Naturalis,Leiden,The Netherlands;3.Lajuma Environmental Research Centre,Makhado,South Africa |
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Abstract: | Amphilius uranoscopus is a catfish species, restricted to rivers and streams in east, southern and central Africa. It is likely to be displaced
due to both competition and predation by exotic trout and other introduced fish. In high altitude mountain streams it can
be the only species occurring, which means that this habitat may act as a refuge for this species. Ecosystems like this are
threatened by habitat alteration and are therefore in need of protection. The abiotic environment, population structure, behavior
and feeding biology of Amphilius uranoscopus were studied in a small, high-altitude perennial tributary of the Limpopo River in the Soutpansberg mountain range, Limpopo
Province, South Africa, during 2005–2006. Here A. uranoscopus showed nocturnal behavior. It used dark hollow crevices in rapids as shelters during the daytime. The rapids are characterized
by a high flow rate, high dissolved oxygen content and coarse riverbed substrate consisting mainly of boulders without fallen
leaves. In contrast to the adults, juveniles found shelter among the fallen leaves in pools. At night, A. uranoscopus moved out of the rapids into the open water of the pools. The main food of A. uranoscopus consisted of macroinvertebrates, mainly Trichoptera larvae. Amounts of algae and detritus in its diet were negligible. A. uranoscopus foraged mainly in rapids and on rock surfaces, spending less time foraging between the fallen leaves at the bottom of pools,
in open water, at the surfaces of bottom and bank and near the water surface. At the water surface, it also fed opportunistically
on terrestrial insects that dropped into the stream, like flying termites. A. uranoscopus was the top predator of the stream system and reached a high density (0.71 fish m−2). There was no competition from other fish species at the study site as they were lacking. A. uranoscopus showed a striking ability to climb and cling on to vertical substrates to conquer waterfalls and very shallow streams that
sometimes become dry, using its fins, adhesive body and protruding mouth teeth. |
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Keywords: | Amphilius uranoscopus Refuge habitat Behavior Diet analysis Stable isotopes |
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