Avaliação dos impactos da carcinicultura sobre os habitats e qualidade da água nos ecossistemas costeiros do território do Baixo Sul da Bahia

Abstract

Worldwide, aquaculture activities have experienced significant economic growth over the past three decades. In Brazil, aquaculture has intensified, particularly shrimp production known as shrimp farming, which is the primary seafood for consumption, leading to high demand for the product. In the state of Bahia, especially in the Baixo Sul region, the rapid growth of shrimp farming has caused significant damage to coastal ecosystems, resulting in the loss of natural habitats for the construction of ponds and discharge of aquaculture effluents altering the properties of surface waters. This study evaluated the degree of environmental quality impact caused by shrimp farming in the Baixo Sul territory. Therefore, a spatiotemporal modeling was developed using land use and land cover data generated by Mapbiomas (collection 7) through GEE and further mapping in QGIS version 3.22.6, using linear models from RStudio to test loss or gain between variables. Results by municipality in the Baixo Sul territory showed that in Valença, shrimp farming was responsible for losses in wetland areas (R² = 0.893, Est = -0.002, t = -2.802, p 0.008). In Nilo Peçanha, shrimp farming was responsible for mangrove loss (R² = 0.727, Est = -0.625, t = -3.256, p 0.007). In Ituberá, the most affected classes were apicum (R² = 0.688, Est = –0.001, t = -5.237, p < 0.001) with losses caused by shrimp farming. Additionally, analyses of physicochemical, microbiological, and trace metal parameters were conducted through water and sediment collection in the Municipality of Valença, distributed in two surface water bodies with fresh, brackish, and saline appearances, during different periods (rainy and less rainy) using Standar Methods. Results were compared with Conama Resolution 357 and 454, showing concentration variations during collection periods: DO (4.1-4.9 mg/L), pH (9.2-8.13), thermotolerant coliforms (1100-68 MPN), metals in water Al (5.1-4.18 mg/L), Fe (3.86-1.16 mg/L), Mn (0.22-1.32 mg/L). PCA analysis and Pearson correlation indicated that covariation patterns of parameters differed regarding sampling points and collection periods. Higher concentrations of Al, Fe, Mn, Ni, and Zn, compared to legislation, were related to the local lithology, and parameters such as DO, pH, temperature, and salinity were the main variables responsible for the behavior of elements Cr, Cu, and Zn, demonstrating that their concentrations not only occur naturally, with shrimp farming being one of the activities altering the physical, chemical, and biological parameters of the aquatic environment. The results of this study demonstrated the environmental impacts produced in the construction (spatiotemporal modeling) and operation (parameter analysis) processes of shrimp farming, highlighting the importance of periodically assessing and monitoring activities in the Baixo Sul region.