Estrutura da comunidade e alimentação dos peixes da Baia da Onça, uma lagoa do pantanal do rio Aquidauana, MS

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

Bala da Onça is a perennial oxbow lake by the Aquidauana River. The lake is connected to the river in the beginning of the flood season (late December) and cut off from it around the months of April or May. There were 75 fish species caught in experimental fishery with a purse seine and a drag seine during the period (July-December 1988), when the lake was disconnected from the river. The community is composed mainly of small species, divided into a typical pattern of a few abundant species and a large number of rare ones. The structure of the community can be visualised by looking at the shape of the species-abundance curve and Shannon diversity index (H e = 1.230; H N = 0.541), leading to the conclusion that the species distribution is more uniforme in terms of biomass than in number. The most numerous families encountered were Characidae (79.5%), Curimatidae (13.1%) and Pimelodidae (3.6%), and the most important in biomass were Curimatidae (38.3%), Characidae (28.1%), Loricariidae (10.4%), Pimelodidae (10.1%) and Erythrinidae (4.5%). Concerning the biomass (g/m2), the major findings were achieved during the twilight period and about 14:00 h. These results imply that, during these periods, the movements of the fishes is at the peak. From the months of July to December 1988, when the body of water was at its lowest standing, the amount of fish per catch ranged from 43.6 to 16.7 g/m2, which can be attributedto the reduction of area of photosynthesisand to natural mortality of fish due to predation. In maY/1989when the lake had once again rejoined the river, the average catch was the smallest on record (2.2 g/m2), which is related to the fishes emigration from the lake to the river. On the following June 1989,when the lake was once more isolated from the river, the amount of fish catch increasedto 27.3 9/m2. Therefore, it is possible to say that the lake s ictiomass had been restored, which can be related primarilyto the emigration from the river to the lake. The communitiesthat colonized the body of water in July 1988 and June 1989 were different in terms of species composition, with Renkonen proporcional similarity PS = 0.389. Nevertheless, species distribution in terms of nUmbers was quite similar. The evaluation of the feedinghabits was based upon the analysis of the stomach contents of the most important species. The methods employed were frequency of occurenceand relative abundance, and these two referenceswere combined into a food index. The organic material were determinated from stomachcontents of detritivorous fish species. There are differences among the average organic contents of 6 curimatidae species, in a continuum from 10.4 to 28.7%, which means that there is a sharingof resources among these species. Hemiodus orthonops has an averageorganic content higher than Curimatidae. It was verified that there is a relation between the body shape of the fish and the kind of food they ingest. It was defined the "Food Index Weighed by the Consumer s Biomass (IAW)", for each item, that means a measure of its conversionin biomass of consumers. By IAW, most important itens were: detritus and algi (46.5%, ingested by curimatidae), alges (14.5%, ingested by Loricariidae), fishes (8.4%), insects (6.4%), micro-crustaceous (3.9%) and superior vegetais (2.4%) .

ASSUNTO(S)

peixe - população - mato grosso ecologia peixe - alimentação sul

ACESSO AO ARTIGO

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