The southern coastal region of Brazil is highly productive and many of its oceanographic processes are still poorly understood due to a great number of forces, such as the continental input from the Plata River and Patos Lagoon, several distinct oceanic water masses, and a complex contribution from groundwater. The shelf near Albardão is highly rich in dissolved nutrients, particularly in the coastal zone. The narrow sandy barrier that separates the ocean from Mangueira Lagoon has led us to wonder about the possibility of groundwater, and if it might play a role in the productivity of the surrounding area. In order to test this hypothesis, nutrient data from Mirim and Mangueira Lagoons and from Albardão were collected during a rainy period. The present work shows the need to include groundwater transport from Mangueira Lagoon to the coastal zone as one of the main sources for the productivity in that region. However, for such phenomenon to be quantified and better understood, it becomes necessary to use natural isotopes as tracers of the underground input.
Groundwater; Continental transport; Nutrients; Submarine estuary; South Atlantic Ocean