Water salinity, temperature, pH and turbidity were measured weekly with Horiba U-10 water quality checker (CA, USA). Transparency was determined weekly with a Secchi disk and daily meteorological information on rainfall, evaporation, solar radiation and insolation were supplied by the Universidade Federal do Rio Grande do Norte meteorological station, and presented as week average. The nutrients (NH4, NO3, NO2 and PO4) were sampled weekly (around the noon) and measured (in triplicate) by colorimetric analysis (FEMTO® 600S) according to Strickland & Parsons (1972). All water samples were filtered (GF/F WHATMAN™), kept in a cool box (≈10°C) and analyzed after 4 hours.