Filtration and biodeposition rates of Crassostrea oysters for southern Brazilian waters

Abstract

Shellfish are considered to be one of the most sustainable sources of animal protein that also contribute substantial ecosystem services back into the environment in which they are grown. Although filtration and biodeposition services of bivalves have been explored in many parts of the world, less information is available about bivalve-environmental interactions in Southwest Atlantic. In this study, clearance, filtration and biodeposition rates for oysters Crassostrea gigas, Crassostrea gasar, and Crassostrea rhizophorae were evaluated in the bays of the island of Florianópolis, Brazil. The data were taken from the end of summer of 2019 until the middle of spring of 2019 in two sites. Temperature, salinity, chlorophyll, seston organic content (OCS), total particulate matter (TPM) and organic particulate material (POM) of seawater were determined and the clearance, filtration and biodeposition rates data were collected. C. rhizophorae showed greater average clearance (3.50 ± 0.21 L h−1 g−1), filtration (66.03 ± 6.82 mg h−1 g−1), and biodeposition rates (63.65 ± 6.62 mg h−1 g−1), indicating that this species processes the greatest amount of water and suspended particles than other species (2.15 ± 0.12, 29.85 ± 2.48, 27.28 ± 2.36 and 1.81 ± 0.12, 29.14 ± 2.36 and 27.58 ± 2.42, respectively for C. gigas and C. gasar). The clearance rate of each species was similar between sites and seasons of the year. However, total particulate matter concentrations were significantly different between sites, with average values of 20.65 ± 7.63 and 15.09 ± 11.97 mg L−1, respectively, for Baía Norte and Sul. Furthermore, clearance rate was correlated with animal weight, TPM and OCS while filtration and biodeposition rates were dependent on seston.