Evaluation of shrimp farming impacts on the water quality of the Lower São Francisco watershed region, Brazil

Abstract

Shrimp farming is one of the fastest growing economic and production activities worldwide, generating both income and development. Principal component analysis (PCA) was applied to assess the effects of shrimp farming on the water quality of catchment, nursery and drainage points in shrimp farms located at the low São Francisco River, one of the most promising regions in Brazil for shrimp production. Physicochemical parameters, including the analysis of cations and anions, were determined at four shrimp farms in the municipalities of Igreja Nova/AL (F1), Propriá/SE (F2) and Brejo Grande/SE (F3 and F4) during four sampling campaigns carried out in the period from October 2018 to July 2019. Electric conductivity, turbidity and total dissolved solids presented statistically significant variations (ANOVA, p<0.05), demonstrating the influence of shrimp feed use, ionic pond regulation and bioturbation carried out by the farmed crustaceans in rearing ponds. Chemical and biochemical oxygen demand, total organic carbon, total phosphorus, NO₃^- and NO₂^- values demonstrate the presence of high organic material, nitrogen and phosphorus concentrations, mainly at the nursery and drainage sampling points. The PCA revealed three main groups responsible for 75.1 % of the total data variation, characterized by organic, nitrogenous and ionic parameters, indicating water contamination by shrimp farming activities, with similarities between drainage points. This ground-breaking study showed that the progressive development of shrimp farming in the study region has the potential to adversely affect water quality if preventive and control measures are not put in place.