Distribuição da macrofauna bentónica da zona sub-litoral da Baía de Maputo

Abstract

This study intends to make a simple contribution to the knowledge of benthic macrofauna communities existing in the sub-coastal area of ​​Maputo Bay, the factors related to their distribution and the effect of spatial variation in the incidence of these factors on the state of the communities. During the months of February and March 1995, 20 sampling stations (E.A.) were randomly marked in Maputo bay. In each E.A. samples of benthic macrofauna, sediment samples, and water samples were collected and the water depth was measured. Macrofauna and sediment samples were collected with a van Veen clamp of 0.025 square meters of surface area. In each sediment sample, texture, organic matter and carbonate content were determined. In the water samples, salinity and turbidity were determined. A total of 551 individuals of 90 species of macrobenthos were collected, in which polychaetes and bivalves are the most frequent. The sampling stations (E.A.) were classified under the group analysis method using the SPSS.PC statistical program. The analysis of the resulting A.E. cluster shows that the benthic macrofauna of Maputo Bay does not form discrete communities with characteristic species. The grouping of E.A. was based on species richness. The most frequent species in the A.A. is the bivalve Venus verrucosa. The measured environmental factors were grouped into three principal components (C.P.) using the Principal Component Analysis (PCA) statistical program. The sediment texture, water depth, and the content of organic matter and silt-clay in the sediment are the dominant environmental factors in C.P. -that contribute most to the variation of the bay's environment. Through multiple regression it was found that of the three C.P. extracted, only C.P. 2 has a linear relationship with species richness. The turbidity of the water and the carbonate content in the sediment are the dominant environmental factors in C.P. 2. (TRADUÇÃO NOSSA)