Assessment of the ecological quality status of the Sepetiba Bay (SE Brazil): When metabarcoding meets morphology on foraminifera.

In recent years, the region surrounding Sepetiba Bay (SB; SE Brazil) has become a hub of intense urban expansion and economic exploitation in response to ore transport and industrial and port activities. As a result, contaminants have been introduced into the bay, leading to an overall worsening of the environmental quality. The present work applies for the first time a foraminiferal morphology-based approach (M) and eDNA-based metabarcoding sequencing (G), along with geochemical data to assess the ecological quality status (EcoQS) in the SB. Principal component analysis shows that the eDNA and morphospecies diversity as well as most of the taxa relative abundance decline in response to the environmental stress (ES) gradient related to total organic carbon (TOC) and metal pollution. Based on ecological indices, Exp(H'bc) (G), Exp(H'bc) (M), foraminifera ATZI marine biotic index (Foram-AMBI), Foram Stress Index (FSI), and geochemical indices (TOC and Potential Ecological Risk Index), the lowest values of EcoQS (i.e., bad to moderate) are inferred in the innermost part of the SB. Despite minor discrepancies among the six EcoQS indices, an agreement has been found for 63% of the stations. To improve the agreement between the ecological indices, it is necessary to fill the gap in species ecology; information on the ecology of many species is still unknown. This work reinforces the importance of molecular analysis and morphological methods in environmental impact studies and confirms the reliability of foraminiferal metabarcoding in EcoQS assessment. This is the first study evaluating the EcoQS in the South Atlantic by using combined foraminiferal eDNA metabarcoding with morphological data.

Polycyclic aromatic hydrocarbons in sediments from Rodrigo de Freitas Lagoon in the urban area of Rio de Janeiro, Brasil.

Regular (non-alkylated) polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues were determined in sediments from Rodrigo de Freitas Lagoon using gas chromatography with mass selective detector (GC-MSD). Concentrations varying from 405 to 11734 ng x g(-1) were found for total PAHs (regular and alkylated homologues). The study showed a pyrogenic and petrogenic contribution, probably due to the incomplete burning of fossil fuels as a result of the intense traffic of boats and motor vehicles added to the anthropogenic activity of several gas stations present in the region of Rodrigo de Freitas Lagoon. According to the National Oceanic and Atmospheric Administration (NOAA) Sediment Quality Guide, PAHs concentration should not exceed 4000 ng x g(-1) (Long et al., 1995) The obtained data present values above the NOAA limit for some sampling points indicating chronic contamination of those sites probably due to anthropogenic activities related to petroleum and its derivatives.