2014/01/01 by Diego Maia Zacardi, Zacardi, Diego Maia, Aristides Ferreira Sobrinho +3
Environmental Science · Agricultural and Biological Sciences · #Fish biology, ecology, and behavior #Fish Biology and Ecology Studies #Fish Ecology and Management Studies
paper · doi:10.2312/actafish.2014.2.2.1-16
Resumo O presente trabalho constitui um estudo sobre a composicao e distribuicao das larvas de peixes ao longo do canal do igarape da Fortaleza, afluente esquerdo do rio Amazonas, situado entre o municipio de Santana e a capital Macapa. O material analisado e proveniente de coletas realizadas entre os meses de dezembro/2009 e agosto/2010, em cinco pontos de amostragens distribuidos ao longo do canal do igarape da Fortaleza. As amostras foram coletadas por meio de arrastos horizontais na subsuperficie da coluna d’agua, com redes de plâncton com malhas de 200 e 300µm. Utilizou-se analise de variância (ANOVA bifatorial) para avaliar a distribuicao espaco-temporal das densidades medias de larvas. Foram capturadas 719 larvas de peixes, classificadas em 8 ordens, 14 familias, 16 generos e 14 especies. Dentre as especies identificadas, a grande maioria apresenta importância ecologica dentro do ecossistema aquatico. Entretanto, algumas especies como Plagioscion auratus , Plagioscion squamosissimus e Pellona flavipinnis possuem interesse comercial e sao largamente consumidas pela populacao local. As maiores densidades ocorreram nos pontos mais internos (cabeceira) e foram representadas principalmente por larvas de Clupeiformes e Eleotridae, caracterizando a area propicia ao desenvolvimento destes individuos. Nao houve diferenca significativa na distribuicao espaco-temporal de larvas. Entretanto, as maiores densidades foram registradas para os meses de dezembro devido a elevada captura de Clupeiformes e eleotrideos e em junho com maior ocorrencia dos engraulideos e syngnatideos. As familias Clupeidae, Engraulidae, Pristigasteridae, Sciaenidae, Pimelodidae e Tetraodontidae apresentaram ampla distribuicao temporal, com ocorrencia das familias Eleotridae e Rivulidae observada apenas no periodo seco (dezembro e agosto). Os resultados constataram forte relacao negativa dos indices de densidade larval com a precipitacao pluviometrica (y = -0.8279x + 1.4216/R 2 = 0.9022). Portanto, o ambiente estudado desempenha papel fundamental para o desenvolvimento inicial do ciclo de vida dos peixes, fortalecendo a importância deste afluente, sobretudo os ambientes de cabeceira, para a manutencao dos estoques pesqueiros. Abstract This work is a study on the composition and distribution of fish larva in the channel of the Fortaleza stream, a tributary of the left bank of the Amazon River between the cities of Santana and Macapa. Sampling took place between December 2009 and August 2010 at five sampling areas along the stream bank. Samples were taken using plankton nets of mesh 200 and 300µm horizontally towed. A two-factor ANOVA was used to evaluate the spatial and temporal distribution of average larval density. A total of 719 specimens of fish larva were collected belonging to 8 orders, 14 families, 16 genera, and 14 species. The vast majority of the species identified were ecologically important to the aquatic ecosystem, although a few species such as Plagioscion auratus , Plagioscion squamosissimus and Pellona flavipinnis have commercial importance and are consumed by the local population. The highest larval densities occurred at inner areas such as the stream head, and were represented primarily by Clupeiformes and Eleotridae, which indicates this is the best nursing area for these species. There was no significant difference in the spatial or temporal larval distribution. The largest densities were registered in December due to the presence of Clupeiformes and eleotrids, and June, with a higher occurrence of engraulids and syngnathids. Clupeidae, Engraulidae, Pristigasteridae, Sciaenidae, Pimelodidae and Tetraodontidae presented longer temporal distribution with occurrence of the families Eleotridae and Rivulidae restricted to the dry season (august and december). These results show a strong negative relationship of the indices of larval density with rainfall (y = -0,8279x + 1,4216/R 2 = 0,9022). Therefore, the study area has a fundamental role in the initial stages of the life cycle of these fish species, especially in the area of the stream head, and thus for the maintenance of fish stocks.