Variação espaço-temporal do zooplâncton do baixo estuário do Rio Itajai-Açu, SC




The Basin of the Itajaí-açu River is the largest of Santa Catarina State, Southern Brazil, extending 15,111 Km2 and encompassing the states main industrial zone. Next to the river mouth lays the Itajaí Harbor, which is the principal outlet of international trading of the state and one of the main harbors of the country. The estuarine region aggregates sediments and pollutants originated from the entire basin, which is an area characterized by high demographic densities and intense industrial activity, including fishing. Added to these contamination sources, dredging activities next to the harbor characterize the whole estuary zone as a critical area for the study of biological indicators. The objective of this study was to describe the zooplankton of the lower Itajaí-açu River estuary and to relate its specific composition and density with environmental variables. The zooplankton community was analyzed in seven stations with oblique (dec/05 may/07) and surface (jun/05 jan/07) plankton tows. These tows were conducted with a WP-2 net with 200 mm mesh size, 30 cm mouth opening and a mechanical flow meter. In the laboratory, qualyquantitative analyses of zooplankton were made in water aliquots representing 3 to 10% of the total sample volume, examined in Bogorov chambers under a stereomicroscope. Abiotic data such as temperature, salinity, pH and water transparence were also collected. Temperature and zooplankton density positively correlated whereas salinity was found to influence the zooplankton species composition. This composition included 13 main taxonomical groups (including families, genera and species) and 91 identified taxa. Three species associations were identified: (a) a limnic community dominated by Cladoceran Bosmina longirostris, Camptocercus dadayi, Ceriodaphnia quadrangula, Ilyocryptus spinifer, Moina minuta and Copepod Eucyclops serrulatus; (b) a marine zooplankton community, composed by Copepods Acartia lilljeborgi, Centropages velificatus, Oithona ovalis, O. Plumifera, Paracalanus quasimodo, Temora turbinata and Cladocerans Penilia avirostris and Pseudoevadne tergestina; (c) a mixohaline group composed by Copepods Pseudodiaptomus acutus and Pseudodiaptomus richardi


hidrologia sul do brasil southern brazil estuary zooplankton hidrology oceanografia zooplâncton estuário

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