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 <i>Saccostrea cucullata</i> and <i>Crassostrea brasiliana</i>. 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).