Portal de Periódicos da CAPES

VARIAÇÃO ESPAÇO-TEMPORAL NA COMPOSIÇÃO DA COMUNIDADE DE PEIXES DO RIO PASSA CINCO (SP)

2008; Linguagem: Inglês

2639-6459

Alberto Luciano Carmassi,

Fish Ecology and Management Studies

This study was performed in Passa Cinco stream, a main river of Corumbatai River subbasin, and its objective was to characterize the fish community of this stream and to determine patterns of distribution in space and time. For that, data related to the community (richness, diversity and abundance) and to abiotic environment were evaluated. Six samplings were performed in Passa Cinco stream in five sites of different orders, since the headwater, at order 2, until its mouth, at order 6. The following fishery equipment was used: a sieve used on bank vegetation, electric fishery equipment, waiting nets and fish-traps. It was captured 5082 individuals, distributed into 62 species, 18 families and 6 orders. The estimate procedures of richness presented values relatively similar to those found in this research, what indicates that the samples were representative. The use of electric fishery equipment revealed efficiency, because the rarefaction curves regarding the sites where this equipment was used turned out to be close to the asymptote. Meanwhile, at sites where more selective fishery equipment was used, curves presented a growing tendency, indicating that, with an increase of the effort, new species could be found. The diversity, richness and equality indexes were evaluated according to time and space. There was significant difference in the values of those indexes, due to sample sites and time, only for the smaller order sites, considering the individuals captured with electric fishery equipment. An increase of the values happened due to the increase of stream order and rainy season. Similarity analysis presented a separation of larger order sites, as a characteristic of sites of medium and low courses, as well as concerning to the sites of smaller order, typical of headwater area. The analysis of canonical correspondence pointed out the longitudinal gradient, starting from the smaller order sites towards the larger order site. The vectors of current speed and dissolved oxygen were associated to the highest order sites, considering their high values as typical of headwater components. The consequences of environmental conditions, and their reflex on the organisms could be noticed through the community relationships of abundance and biomass and their variation in different orders of the stream. Considering the occurrence of species in Passa Cinco stream, it was verified that the great majority was occasional, however, when sample sites were analyzed separately, it was noticed that usual species prevailed, indicating a difference in composition of species along the gradient. When weight, frequency and number of individuals were related, it was possible to understand, through the main species, how the fish community of Passa Cinco stream is structured. Addition phenomena and substitution of species were noticed, considering that addiction prevailed in closer sites and substitution in more distant sites.