VI.—<i>A synopsis of the Cichlid Fishes of Lake Nyasa</i>

Trewavas, Ethelwynn

doi:10.1080/00222933508655026

Cited by 75 publications

(41 citation statements)

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“…One group which exemplifies the evolutionary capabilities of the family, notably with specializations in feeding morphology and behavior, belong to an apparently monophyletic subset of Lake Malawi cichlids (Fryer & Iles 1972, Ribbink et al 1983, Marsh & Ribbink 1985. Commonly referred to by their Chitonga name 'mbuna', ten genera and about 200 species of these rock-dwelling fishes have been identified (Trewavas 1935(Trewavas , R.ibbink et al 1983. In his classic work, Fryer (1959) suggested that the mbuna community is a 'peaceful condominium' which violates the Gaussian principle of competitive exclusion.…”

Section: Introductionmentioning

confidence: 97%

The feeding habits of a group of herbivorous rock-dwelling cichlid fishes (Cichlidae: Perciformes) from Lake Malawi, Africa

Reinthal

1990

Environ Biol Fish

104

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SynopsisThe feeding habits of a group of tropical herbivorous rock-dwelling cichlid fishes from Lake Malawi, Africa, are investig,ated using stomach content analyses. The various species fed selectively on the periphyton of the rocky shores. Blue-green alga of the genus Calothrix was the most common item ingested by the group. Diatoms (Chrysophyta) also were abundant food items. Discriminant analysis showed that dietary items were good variables to identify species. Interspecific dietary differences showed a continuum from those species feeding primarily on Calothrix to those feeding primarily on diatoms. Algal resources exhibit distinct patterns of spatial variation. Diet was correlated with foraging behavior and trophic morphology. Interspecific differences in diet could possibly facilitate ecological coexistence among various species. Such coexistence would contribute to the maintenance of the high diversity fish faunas characteristic of the Great Rift Lakes of Africa.

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Section: Introductionmentioning

confidence: 97%

The feeding habits of a group of herbivorous rock-dwelling cichlid fishes (Cichlidae: Perciformes) from Lake Malawi, Africa

Reinthal

1990

Environ Biol Fish

104

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“…A large part of this species £ock's taxonomic diversity is represented by the colourful, rock-dwelling species known as`mbuna'. Morphological, ecological, and genetic lines of evidence suggest that the mbuna form a monophyletic group (Trewavas 1935;Fryer 1959a;Oliver 1984;Meyer 1993;Moran et al 1994). Virtually all of the more than 200 described and putative species of mbuna are restricted to rocky habitats less than 40 m deep (Ribbink et al 1983a).…”

Section: Introductionmentioning

confidence: 99%

Population structure and colour variation of the cichlid fishes Labeotropheus fuelleborni Ahl along a recently formed archipelago of rocky habitat patches in southern Lake Malawi

Arnegard

Markert

Danley

et al. 1999

Proc. R. Soc. Lond. B

112

133

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Extremely ¢ne-scale genetic partitioning has recently been detected among populations of Lake Malawi's rock-dwelling cichlids through the study of microsatellite loci. Understanding the mechanisms of genetic di¡erentiation that operate in this rapidly speciating group requires further investigation of the geographic patterns of gene £ow and the congruence between morphological and genetic divergence. In pursuit of this goal, genetic variation at four microsatellite loci and variation in male breeding coloration were examined in several populations of Labeotropheus fuelleborni from southern Lake Malawi. Signi¢cant genetic di¡erentiation exists among populations (overall F ST 0.063; p 0.0002). While migration appears unrestricted within continuous rocky patches, deep waters and sandy bays more than 2 km wide act as strong barriers to gene £ow. Dispersal of L. fuelleborni appears to follow a stepping-stone model in which the distribution of habitats often constrains migration to one dimension. It is hypothesized that clinal colour variation in the study area has resulted from the secondary contact of divergent lineages, although reproductive isolation between colour variants is not apparent. Relative to shoreline populations, reduced levels of gene £ow among populations inhabiting isolated, deep-water islands provides greater opportunities for drift, adaptation to local conditions, or sexual selection to e¡ect genetic di¡eren-tiation in this species.

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“…There exist in the lake, however, a number of unique and interesting cyprinid and catfish speThe littoral, demersal and pelagic fish communities ties, some of which support major fisheries. The of Lake Malawi/Niassa are dominated by cichlids, most important of these is the fishery for the enin terms of both biomass and number of species demic cyprinid, Engraulicypris sardella (Gunther), (Trewavas 1935, Ribbink et al 1983 that uses mainly open-water seines with light attrac-tion in near-shore areas and beach-seines. The catches of E. sardellu fluctuate greatly, probably as a result of fluctuations in primary productivity ) and the recorded catches of 143 to 3 273 metric tons (t) for [1975][1976][1977][1978][1979][1980][1981][1982][1983][1984][1985] are almost certainly too low, with estimated landings potentially reaching 50 000 t in some years .…”

Section: Introductionmentioning

confidence: 99%

Distribution and breeding biology of offshore pelagic cyprinids and catfish in Lake Malawi/Niassa

Thompson¹,

Allison²,

Ngatunga³

1996

Environ Biol Fish

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Lake MalawiNiassa is a permanently stratified lake, consisting of an oxygenated layer of 230 m depth that overlies an anoxic zone that extends to the lake bottom at a maximum depth of over 700 m. Some fish are found throughout the oxygenated zone of the offshore waters, and lead a pelagic existence, although many of the species form part of the demersal community in shallower waters where the lake-bed is oxygenated. This paper reports on the distribution of cyprinids and catfish at six offshore locations, sampled with a mid-water trawl and gillnets, along the north-south axis of the lake. These two groups formed, respectively, 5% and 13% of the offshore fish biomass in the trawl catches. The offshore cyprinids comprised the small lake-spawning Engraulicypris sardella, the only species to have pelagic larvae, and the larger river-spawning Opsaridium microcephalum and 0. microlepis. These cyprinids occurred mainly in the upper 100 m of the water column. The biomass of both larvae and adults of E. sardella showed considerable fluctuations over the two years of study. The spawning site of E. sardella remains a mystery, but is no longer believed to be in the offshore pelagic zone. The most abundant catfish was the mochokid Synodontis njassae, that exhibited diurnal movements from just above the oxic-anoxic boundary layer during the day to the surface layers at night. The clariid catfish of the genus Bathyclarias were caught infrequently offshore, but owing to their large size, they could form a significant part of the biomass. Their abundance was difficult to quantify, as it was believed that the majority are active in the nearsurface layers and were under-sampled by the trawl and gillnets. Information on some aspects of the breeding biology is included in the paper, although our knowledge in this area is very incomplete.

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VI.—A synopsis of the Cichlid Fishes of Lake Nyasa

Cited by 75 publications

References 0 publications

The feeding habits of a group of herbivorous rock-dwelling cichlid fishes (Cichlidae: Perciformes) from Lake Malawi, Africa

The feeding habits of a group of herbivorous rock-dwelling cichlid fishes (Cichlidae: Perciformes) from Lake Malawi, Africa

Population structure and colour variation of the cichlid fishes Labeotropheus fuelleborni Ahl along a recently formed archipelago of rocky habitat patches in southern Lake Malawi

Distribution and breeding biology of offshore pelagic cyprinids and catfish in Lake Malawi/Niassa

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