Abundance, distribution, and territory areas of rock-dwelling Lake Tanganyika cichlid fish species

Hydrobiologia (Impact Factor: 2.21). 12/2008; 615(1):57-68. DOI: 10.1007/978-1-4020-9582-5_5

ABSTRACT Lake Tanganyika, the second-oldest and second-deepest lake in the world, harbors an impres-sive cichlid fish fauna counting about 250 endemic species that are characterized by a great level of ecological, morphological, and behavioral specializa-tion. This study describes and compares cichlid fish communities at two rocky shores with differential human impact in the south of Lake Tanganyika. Species inventories and depth-dependent abundances were elaborated. About 41 and 46 sympatric cichlid species were recorded in the two study sites, respec-tively. Variabilichromis moorii was the most abundant species (29–60% of total number of fishes), followed by Aulonocranus dewindti (3–19%), Tro-pheus moorii (12%), Ophthalmotilapia ventralis (4–10%), Eretmodus cyanostictus (6–11%), and Cyathopharynx furcifer (0.01–9%). All other species had abundances below 5%. It further emerged that large cichlids such as Petrochromis species, Cyatho-pharynx furcifer, and Lobochilotes labiatus were very rare at one location, with frequencies of 0.55% or less. Territorial sizes of three particularly abundant species, Variabilichromis moorii, Aulonocranus dew-indti, and Tropheus moorii, were assessed by behavioral observations. We distinguished between territorial core areas and total defended area, yielding average core areas between 0.4 (V. moorii) and 1.6 m 2 (T. moorii), and total defended areas averag-ing for each species between 1.6 (V. moorii) and 5.0 m 2 (A. dewindti) with no significant differences between the two study sites. The data on individual densities are also relevant for evolutionary studies, in that they allow more accurate calculations of effec-tive population sizes.

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