Isotopic Data of Oysters and Seston from Arraial do Cabo

Seawater was collected in 4 L triplicate samples at each site to analyze stable isotopes in the seston. Samples were vacuum filtered using 0.7 µm GF/F filters (Schoo et al., 2018). Six individuals from the Ostreidae family were collected at each sampling point and identified as Saccostrea cucullata and Crassostrea brasiliana. Each specimen's gills, hepatopancreas, and muscle tissues were separated, weighed, and macerated. All samples were collected during the low spring tide in December 2021.The quantification of stable isotopes (δ13C and δ15N), total carbon (TC) and total nitrogen (TN) was performed on aliquots of dry filters and of each freeze-dried oyster tissue.TC, TN, δ13C, and δ15N levels were quantified using an elemental analyzer coupled to an isotope ratio mass spectrometer (EA Flash 2000 coupled to an IRMS Delta Advantage; Thermo Electron Corp., Bremen, Germany), as described by Vezzone et al. (2021).