Water bodies located in coastal areas are subject to human pressures and the loss of environmental quality. The objective of this study was to evaluate the environmental quality of the river Papaquara through water quality and river landscape, using the Trophic Index (TRIX) and Rapid Assessment Protocol (RAP). The study was developed in the watershed located in the north of the island of Santa Catarina, Florianópolis -SC, whose population increase in the summer is around 280%. The Trophic Index and the Rapid Assessment Protocol were evaluated in the pre-summer period, summer and after-summer in seven sample points along the inner areas (higher population density), median and outside the Papaquara river, plus two points in affluent. The river Papaquara showed up in great stress state, is classified as eutrophic, 77% of the samples and changed in 50% of the sampled area, as the TRIX index and RAP, respectively. The internal area registered up eutrophic and impacted in all periods analyzed. The median area and the outer decreased their water quality, due to summer activity, while there was no change in environmental quality by RAP. A significant correlation between the indices used indicated that the RAP should be used with caution to describe the condition of water quality. This analysis has submitted be more appropriate when used in river scale as a whole, but not isolated segments.Keywords: Eutrophication; TRIX; Rapid Assessment Protocol; Papaquara river. RESUMOOs corpos hídricos localizados nas zonas costeiras estão submetidos às pressões antrópicas e a perda da qualidade ambiental. O objetivo deste estudo foi avaliar a qualidade ambiental do rio Papaquara, através da qualidade da água e da paisagem ribeirinha, utilizando-se do Índice Trófico (TRIX) e do Protocolo de Avaliação Rápida (PAR). O estudo foi realizado na bacia hidrográfica localizada no norte da Ilha de Santa Catarina, Florianópolis -SC, cujo aumento populacional no veraneio é em torno de 280%. O Índice Trófico e o Protocolo de Avaliação Rápida foram avaliados nos períodos de pré-veraneio, veraneio e pós-veraneio em sete pontos amostrais ao longo das áreas interna (maior adensamento populacional), mediana e externa do rio Papaquara, além de dois pontos em afluentes. O rio Papaquara mostrou-se em estado de forte estresse, sendo classificado como eutrofizado, em 77% das amostras e alterado em 50% da área amostrada, conforme os índices TRIX e PAR, respectivamente. A área interna apresentou-se eutrófica e impactada em todos os períodos analisados. A área mediana e a externa diminuíram sua qualidade da água, devido a atividade de veraneio, enquanto não houve alteração da qualidade ambiental pelo PAR. A correlação significativa entre os índices utilizados indicou que o PAR deve ser usado com cautela para descrever condição de qualidade da água. Esta análise se apresentou mais adequada quando utilizada na escala do rio como um todo, mas não por segmentos isolados.

Dinâmica diurna das formas de carbono inorgânico e oxigênio dissolvido em viveiro de tilápias do Nilo (Oreochromis niloticus Linnaeus,

No abstract

In this study, the ecotechnology artificial floating islands (AFIs), colonized by Eichhornia crassipes, have been tested as a tool for water quality improvement of fishponds. The experiment was carried out in semi-intensive production during the grow-out period of Nile tilapia, comprising one production cycle. It was completely randomized with two treatments (with and without AFIs) and three replications. Temperature, dissolved oxygen, conductivity, pH, turbidity, total dissolved solids (TDS), transparency (Secchi) and concentrations of chlorophyll a (CL a), total nitrogen (TN), total ammonia nitrogen (TAN), total phosphorus (TP) and orthophosphate (PO43--P) were analyzed fortnightly in the fishponds. Two groups ordered based on environmental characteristics were formed by applying the Principal Component Analysis (70.68% of explicability). The fishponds with AFIs were assigned to higher values of Secchi and lower values of pH, turbidity, TDS and concentrations of nutrients. On the other hand, the fishponds without AFIs were assigned to the highest values of these variables, except for Secchi. In 30 days, the AFIs showed the lowest concentrations of TP and PO43--P, and for CL a, TN and TAN, the differences were recorded after 90 days. The use of AFIs has demonstrated potential to conserve water quality in fishponds, notably for biologically assimilable elements (PO43--P  and TAN) and for those directly related to eutrophication (P and N). Artificial floating islands should be encouraged for small and medium-sized farmers as tool to improve water quality in fishponds. However, new AFIs coverage rates must be evaluated, as well as the control of hydraulic retention rates. Keywords: aquaculture, ecotechnology, free-floating aquatic macrophytes.

Anthropic changes in coastal watersheds affect the quantity and quality of water in estuaries. Based on an analytical model of saline intrusion and load balance, we have evaluated the effects of effluent discharge (mean of 285 L·s−1 and peak of 495 L·s−1) from a wastewater treatment plant (WWTP) in an island estuary. Saline intrusion at low tide, without actual anthropic discharge, will increase by 22%, whereas with increasing discharge, reductions of 16% and 28%. The reduction of saline intrusion may affect biogeochemical processes and the distribution of species in regions further up the estuary. When the WWTP reaches the mean projected discharge, it will increase its BOD and phosphorus loads by 90% and 82%, respectively, in relation to the current load. With the increase of WWTP discharge, there will be an expansion of hypoxic and anoxic conditions over the current areas, worsening the condition of this already jeopardized estuary. For the WWTP to lead to the expected environmental gains, it is necessary to consider the carrying capacity of the receiving body.