Estudo da biodiversidade da comunidade zooplanctônica no rio Bodocongó e sua aplicação como bioindicadoras dos níveis de poluição/eutrofização.

Abstract

The Bodoeongo river (Paraiba State) is in the Medium Paraiba river basin. This region is part of the Drought Polygon and characterized by the irregularity of rain distribution and for the succession of droughts. Its basin extends for 981 km2; this river starts at the municipal district of Puxinana (7 33 S, 35 57 W) in an altitude of 691 m above sea level and it extends for 78 km in the north-south direction ending in the Paraiba river in Barra of Santana at 310 m above sea level. Its regional importance is due to the intense use of those waters by the riverine population (unrestricted irrigation, bricks production, clothes washing and recreation) and because is part of the macro drainage system of the city of Campina Grande (the second largest city of the state, with 360.000 hab). Along its course receives punctual and diffuse contributions of domestic sewage and of some industries. The present study aimed the viability of zooplanktonic species use as biological indicators of pollution/eutrophication level of the river, to correlate the species identified with the physical and chemical variables and to study the spatial and temporal distribution of these species along 7 sampling points in the river (along the Medium and Low Bodoeongo river) which were monitored monthly from december/99 to november/00. The physical and chemical parameters (pH, temperature, electric conductivity, dissolved oxygen, BOD5, suspended solids and fractions, among other) followed APHA (1995) recommendations except for nitrate (RODIER, 1975). The zooplanktonic community was studied in samples collected with plankton net (mesh of 50um) and preserved with formal in sugar 4% solution. The Shannon-Weaver Diversity Index and Euclidian Relative Distance were calculated. The results showed that the zooplanktonic community was characterized by the predominance of Rotifera followed by the Copepoda and Cladocera. The predominant species of Rotifera is B. angularis chelonis, B. caudatus, B. calyciflorus and Filinia longiseta were typical species of eutrophic environment. The lowest diversity index were found in the Medium Bodoeongo river (hipereutrophic). The highest densities of Rotifera were observed during the drought period, which reached values as high as 850 ind/L. The physical and chemicals variables characterized the river as strongly polluted similar to domestic sewage. The river was included in the Class 4 of CONAMA (20/86) being not suitable for the activities developed in its margins.