Studies were carried out to determine species richness and abundance of rock-dwelling cichlids, Mbuna, in Lake Malawi. A total of 40 heterogeneous sites which yielded 10 genera, 136 species and a species-genus ratio o...Studies were carried out to determine species richness and abundance of rock-dwelling cichlids, Mbuna, in Lake Malawi. A total of 40 heterogeneous sites which yielded 10 genera, 136 species and a species-genus ratio of 13.6, were surveyed by scuba diving in transects laid at six depths on each site. Species diversity and abundance were generally high in the rocky bottom habitats with a general trend of the two variables decreasing with depth, except at Likoma and Chizumulu Islands where they increased with increasing depth. This was due to dominant species inhabiting water depths of 10 to 15 m. Relative abundance was generally low in all the sites where few species had relative abundance of more than 10%. The same was applied to relative site frequency; more than 60% of the species were rare with relative site frequency of less than 10%. These low estimates support the fact that most of the Mbuna species are endemic within localities in the lake. Southern part of the lake has lower abundance and richness of Mbuna with the exception of islands compared to the northern part of the lake. This is explained by high prevalence of sandy and muddy lake bottom in the south as opposed to rocky bottom in the north.展开更多
文摘Studies were carried out to determine species richness and abundance of rock-dwelling cichlids, Mbuna, in Lake Malawi. A total of 40 heterogeneous sites which yielded 10 genera, 136 species and a species-genus ratio of 13.6, were surveyed by scuba diving in transects laid at six depths on each site. Species diversity and abundance were generally high in the rocky bottom habitats with a general trend of the two variables decreasing with depth, except at Likoma and Chizumulu Islands where they increased with increasing depth. This was due to dominant species inhabiting water depths of 10 to 15 m. Relative abundance was generally low in all the sites where few species had relative abundance of more than 10%. The same was applied to relative site frequency; more than 60% of the species were rare with relative site frequency of less than 10%. These low estimates support the fact that most of the Mbuna species are endemic within localities in the lake. Southern part of the lake has lower abundance and richness of Mbuna with the exception of islands compared to the northern part of the lake. This is explained by high prevalence of sandy and muddy lake bottom in the south as opposed to rocky bottom in the north.
