SEDIMENTARY AND ENVIRONMENTAL CHARACTERIZATION OF THE POTENGI-RN RIVER ESTUARY AND ITS ADJACENT SHELF
Potengi estuary, inner shelf, benthic foraminifera.
Benthic foraminifera are widely used as bioindicators, especially in environments with high levels of pollution and anthropogenic interaction. We collected 59 sediment samples through Van Veen grab sampler, as well as physical-chemical data from the water column using the CTD (conductivity, temperature and depth) equipment. The objective is the sedimentary and environmental characterization of the Potengi River estuary and the adjacent inner continental shelf of Rio Grande do Norte. The study area is located between Presidente Costa e Silva and Nilton Navarro bridges, while the continental shelf area is located between the beaches of Mãe Luiza in the south and Redinha Nova in the north, approximately 10 km from the coast. Data on granulometry, carbonate, organic matter content, sedimentary facies and benthic foraminiferal distribution were studied. PCA (Principal Component analysis) and Cluster analyses divide the area into three parts. First part is the estuary, where fine to medium sands predominate, and foraminiferal assemblages show presence of pollution in the river channel. The second part is the central portion of the inner shelf, which has carbonate sedimentation and a great abundance of foraminifera. The third part is also located on the inner shelf, but has siliciclastic sediments and low abundance of foraminifera. Amonnia tepida are predominant in the estuary and Quinqueloculina lamarckiana in the shelf. The abundance of Amonnia tepida and the low concentration of the other species in the estuarine region probably revealed a high stress environment.