Zooplankton community change after impact of the Via Expressa Sul works – Southern Bay of Santa Catarina Island

Abstract

. In order to solve traffic problems in the capital, the government of the Santa Catarina State began in 1996 dredging works and hydraulic embankment in the “Saco dos Limões”, south bay of Santa Catarina Island. Studies of environmental impact accomplished by CTTMar (1996/1997) verified that the dredging activities altered the community of the local zooplankton. The present work studied the zooplankton community 6 years after the end of the dredging activities, diagnosing the possible alterations in the environment. The zooplankton samples were obtained between 1996 and 1998 (Phase 1, impact) and from 1999 to 2002 (Phase 2, after impact) by superficial hauls using a net WP-2 type with 200 mm of mesh size. The community’s typical species found were the copepods Acartia lilljeborgi, A. tonsa, Oithona oswaldocruzii and Paracalanus quasimodo. Among the two phases a significant decline was observed in the density of the zooplankton. A. tonsa, typical estuarine copepod was substituted by A. lilljeborgi inside of the bay. The same was observed for P. quasimodo that substituted O. oswaldocruzii in the intern area. These results suggest the hydrological changes in function of the increase of the depth, decrease of the area and the residence time of the water, impeding the development of estuarine community that was characteristic before the dredging and hydraulic embankment activities.