Diet and ecomorphological relationships of four cichlid species from the Cuiabá River basin

ABSTRACT Relationship between diet and morphology of cichlid were analyzed considering that the trophic apparatus determines differential food use among species. Cichlasoma dimerus and Satanoperca pappaterra showed a generalist diet, while Chaetobranchopsis australis and Crenicichla vittata consumed zooplankton and fish, respectively. Significant correlation between morphology and diet was not found, but C. australis differed from the others species in the upper mouth and longer gill rakers. The morphology data and food size segregated the cichlids into three groups. The first was comprised by C. australis, which has many and longer gill rakers and a more protractile mouth, the second by C. vittata, which have a larger and more-protruded mouth and the third by S. pappaterra and C. dimerus, with a smaller and lower mouth. The latter two groups have more widely spaced gill rakers and consumed larger food. Overall, our results showed different patterns of species grouping when considering morphological or diet data. However, to C. australis the gill rakers determine both the type and size of food

Ecologia alimentar da corvina, Pachyurus bonariensis (Perciformes, Sciaenidae) em duas baías do Pantanal, Mato Grosso, Brasil Feeding ecology of Pachyurus bonariensis (Perciformes, Sciaenidae) in two bays of the Pantanal, Mato Grosso State, Brazil

Foi investigada a dieta de Pachyurus bonariensis Steindachner, 1879 associando-a à variações espaciais, temporais e ontogenéticas. Os peixes foram coletados mensalmente de março/2000 a fevereiro/2001 e de agosto/2002 a fevereiro/2003 em duas baías do Pantanal, Chacororé e Sinhá Mariana. Conteúdos estomacais de 359 exemplares foram analisados através dos métodos de freqüência de ocorrência e volumétrico. A dieta foi composta essencialmente por larvas bentônicas de Chironomidae e Ephemeroptera, independente do local e período (seca e cheia) analisados. Entretanto, nota-se marcante diferença na composição alimentar de acordo com o tamanho do peixe. Os menores exemplares (comprimento padrão = 1,6 a 7,2 cm) consumiram preferencialmente Chironomidae e os maiores (comprimento padrão = 13,0 a 18,6 cm) Ephemeroptera. Conclui-se que P. bonariensis tem hábito alimentar bentívoro e especializado, devido principalmente ao restrito espectro alimentar aliado à posição e forma da boca adaptada a explorar o substrato.<br>Spatial, temporal and ontogenetic variations in the diet of Pachyurus bonariensis Steindachner, 1879 were analyzed. Fishes were taken monthly from March 2000 to February 2001 and from August 2002 to February 2003 in the Chacororé and Sinhá Mariana bays. Diet was determined analyzing 359 stomach contents. To express diet results, were used occurrence and volumetric methods. The individuals consumed expressive amount of Chironomidae and Ephemeroptera larvae, in both bays and periods (dry and wet). Ontogenetic analysis showed that small individuals (Standard length = 1.6 to 7.2 cm) ate mainly Chironomidae, whereas larger ones (Standard length = 13.0 to 18.6 cm) consumed mainly Ephemeroptera. Then it is possible to infer that P. bonariensis is benthic-feeding fish with specialized diet. This characteristic was attributed because its narrow niche breadth allied with position and form of its mouth adapted to feed on the bottom