CAMBORIÚ RIVER ESTUARY: INTRATIDAL VARIATION AND NET TRANSPORT OF DISSOLVED NUTRIENTS, POC AND CHLOROPHYLL A DURING NEAP AND SPRING TIDE CONDITIONS

Abstract

The purpose of this study was to evaluate the intratidal variability and to quantify the net transport of dissolved nutrients, particulate organic carbon (POC) and Chlorophyll a in the estuary of the Camboriú River during neap and spring tides. Two 25-hour continuous sampling surveys were carried out, covering two tidal cycles on each situation. On each survey, continuous records of direction and velocity of currents and vertical profiles of salinity and temperature were obtained, as well as samples of surface and botton water. The distribution of dissolved nutrients was determined by the tide during spring tide conditions and by the river discharge during neap tide conditions. In the spring tide the net transports of DIN, DIP, Si, POC and Chla-a through the estuary were -2.6x104, -0.9x103,-9.9x103 e -1.9x103 (mol/d) and 50 (g/d), respectively. In the neap tide, the net transports of DIN, DIP, Si, POC and Cla-a were -1.5x104, -0.35x103, -23x103, -4.4x103 (mol/d) e -2.0x103 g/d, respectively. The largest transfers of Si and POC in the neap tide may be associated to the rainy period in this situation. The smallest transport of DIN and DIP can be explained by its adsorption into the particulate material and by its biological consumption. The second hypothesis is reinforced by the export of Cla-a from the estuary.