Mussels (Perna perna) and oysters (Crassostrea brasiliana) as bioindicators of microplastic contamination in the Santos estuary (SP)

Abstract

In 2050 there will be more plastic than fish in the oceans, as this is currently the most abundant material among marine litter (between 61 and 87%), besides having slow degradability in marine and coastal environments. The occurrence of plastic polymers can lead to aesthetic, economic, social and biological damages in coastal environments. Microplastics (MPs), of small dimensions (5mm), are formed from the fragmentation of larger pieces or directly released into environments as by-products and consumer goods. Currently, this type of residue is often found in different environmental matrices such as water, sediments and organisms; even in remote areas such as the underwater trenches and small oceanic islands. Due to their lifestyle, filter-feeding organisms have been considered good models for the evaluation of environmental contamination by MPs. On the central coast of the state of São Paulo, the Santos-São Vicente estuarine system shelters the largest population densities in the state, a relevant port complex in Latin America and is influenced by releases from petrochemical, steel and fertlizing industries. In this system, a gradient of contamination by hazardous chemicals has been established, whose concentrations are progressively lower towards Santos bay, located at the outfall of the estuary. On the rocky shores distributed along this area, large natural banks of mussels (Perna perna) and oysters (Crassostrea brasiliana) are found for which there are previous records of contamination by MP. Considering these scenarios, this project aims to evaluate, along gradient sites, the accumulation rates of MPs in these species, seeking to determine which filter-feeding organism present the best bioindicator potential. During the sampling campaigns will be identified, collected and labeled 40 organisms of each species and the physicochemical parameters of the sites will be measured. In laboratory 15 organisms of each species and site will be used in analysis of neutral red dye retention time in lysosomes of hemocytes. Subsequently, using washing procedures, biometrics, soft tissue separation, digestion, filtration and spectroscopy in the Fourier Transform Infrared Region (FTIR), the accumulation rate and composition of MPs may be determined. The implementation of this proposal will allow, over 24 months, determining the species with the best performance to be used as an indicator of this type of impact. Therefore, considering the emerging concern arising from the release of this type of waste in natural environments, the knowledge generated will be of fundamental importance for the execution of MPs monitoring programs. Furthermore, the eventual granting of the requested scholarship will contribute to the formation of a student at the graduate level, as well as to the generation of academic products such as scientific articles to be published in journals of high impact factor and selective editorial policy. (AU)