ZooplÃncton demersal na Ãrea de proteÃÃo ambiental de Tamandarà (apa dos corais) Pernambuco (Brasil)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Studies were carried out at the Environmental Protection Area of Tamandarà (PE - Brazil) to test traps efficiency in the collection of demersal zooplankton, verifying the light effects in the organisms migration, the influence of different mesh sizes, seasonal variations, substrate effects, the biodiversity and the role of this community in the reef area. Samples were collected in two fixed stations (reef and rubble), at the rainy (July/2000) and dry (January/2001) seasons. These collections were made during three consecutive days during neap tide. The 46 samples of demersal zooplankton were obtained with eight traps in each substrate, four of which had 125μm mesh size (two with light and two without light) and the other four with 300μm mesh size (two with light and two without light). These traps were fixed on the substrates at 6 p.m. and samples collected at 6 a.m. After collections samples were fixed with 4% neutralized formaldehyde. In laboratory, the biomass was obtained by the wet weight method. Zooplankton qualitative and quantitative analysis were made under a compound microscope. Temperature varied from 24.0ÂC to 25.25ÂC at the rainy season and from 27.0ÂC to 28.8ÂC at the dry season. Salinity varied from 31.60 to 33.70 at the rainy season and from 30,69 to 32,0 at the dry season. The traps used in Tamandarà showed to be efficient in demersal zooplankton collections. The community was composed by holoplanktonics (56%), meroplanktonics (15%) and tycoplanktonics (29%) from oceanic and estuarine origin. Biodiversity was high with 118 taxa, due the presence in the zooplankton community of the demersal taxa. Copepods were the most abundant in the 125 μm mesh size trap and crustaceans larvae in the 300 μm mesh size trap. Taxonomic differences among samples were minimum. Species diversity was high (>3 bits.ind-1). Average biomass varied from 0,09 g.m-2 (rainy season, trap 125 μm) to 75,09 g.m-2 (rainy season, trap 125 μm). Zooplankton density of the 125 μm mesh size trap (~659,153.84 org.m-2) was much higher than those of 300 μm (~186,483.60 org.m-2), although it was not registered significant difference (p>0.05). Traps without light presented higher density, however it was not registered significant difference (p>0.05). Higher differences between reef and rubble bottoms was in density, with higher amounts at reef although not significant statistically (p>0.05). Differences were registered between rainy and dry seasons (p<0,05), with higher biomass at the rainy season and higher density at the dry season, this high quantity made of organisms of smaller sizes. Throphic migrations by most of the demersal zooplankton community shows its important role structuring the reef community

ASSUNTO(S)

recifes de coral zooplÃncton estuÃrio oceanografia trap light demersal

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