SUSCEPTIBILITY TO EUTHROPHIZATION AND FUTURE SCENARIOS IN COASTAL WATERSHED

Abstract

The watersheds suffer anthropic pressures which cause environmental stress, such as the eutrophication process that causes loss of environmental susceptibility. This research aimed at
connecting the eutrophication process with anthropogenic factors, such as: population growth,
sewage collection coverage and treatment and urban planning. In this study, three watersheds in
Ilha de Santa Catarina, Florianópolis – SC were analyzed: Itacorubi, Ratones and Tavares. The
following models based the estuary trophic state evaluation: Land Ocean Interactions in the Coastal
Zone (LOICZ) and Assessment of Estuarine Trophic Status (ASSETS). Those models assisted in
comprehension processes related to the loss of health of aquatic ecosystems in a holistic
perspective. The hydrographic basins trophic state was considered from mesotrophic to eutrophic.
Simulated scenario showed that the estuaries need ways to reduce the antrophic pressure through
increasing the collection coverage and sewage treatment. The scenario simulation highlighted which
the mitigating measures should be considering the good condition of the environmental ecological
state through the investigation of physical, biogeochemical, and anthropic characteristics.
Therefore, it is important to enlarge sanitary sewage in different treatment levels for the maintenance or reversal of the current estuaries condition.