HR: 10:45h
AN: OS22A-02    [Abstracts]
TI: Oceanographic Processes in the Region of Fluvial Influence of the Itajaˇ-A‡u River
AU: * Schettini, C A
EM: guto@univali.br
AF: University of Vale do Itajaˇ-UNIVALI, R.Uruguai, 458 CP 360, Itajaˇ, SC 88302202 Brazil
AU: Truccolo, E C
AF: University of Vale do Itajaˇ-UNIVALI, R.Uruguai, 458 CP 360, Itajaˇ, SC 88302202 Brazil
AU: Pereira, J
AF: University of Vale do Itajaˇ-UNIVALI, R.Uruguai, 458 CP 360, Itajaˇ, SC 88302202 Brazil
AU: R”rig, L R
AF: University of Vale do Itajaˇ-UNIVALI, R.Uruguai, 458 CP 360, Itajaˇ, SC 88302202 Brazil
AU: Resgalla, C
AF: University of Vale do Itajaˇ-UNIVALI, R.Uruguai, 458 CP 360, Itajaˇ, SC 88302202 Brazil
AB: The oceanographic processes in the region of fluvial influence (ROFI) of the Itajaˇ-A‡u river were assessed through fourteen monthly surveys from November 2002 until December 2003. The main objective of this study was to investigate the effects of the fluvial riverine in the physical, biogeochemical and biological processes in the ROFI. Twenty eight sampling stations were positioned in five transects oriented in a radial shape from the estuarine mouth, with further two stations in the estuary. The transects length was about of 5-km each, reaching the isobath of 25 m. CTD, turbidity and dissolved oxygen profiles were acquired in all stations. Chlorophyll-a were sampled at surface in all stations. Water samples for determination of suspended particulate matter, dissolved inorganic nutrients, chlorophyll-a, phytoplankton and bacterioplankton were sampled in ten stations at surface and near bottom levels. The water samples stations were taken in selected stations to cover all studied area, where was also sampled zooplankton with a ring net. Current speed and direction were acquired with an ADCP moored about 1.5 km off the estuarine mouth at 10 m deep, from November 2002 until March 2003. The river discharge was below the average during most of the sampling period. Although, low salinity water was a permanent feature in the vicinity of the estuarine mouth. The estuarine plume dispersion was allways to north-northeast, what was observed by surface low salinity and higher concentrations of dissolved inorganic nutrients and chlorophyll-a. Below the surface layer, in all ROFI, the water column was dominated by salinity about of 33, named as Coastal Waters. Oceanic waters (salinity higher than 35) were observed only during the summer, with presence of Tropical Water and South Atlantic Central Water. Currents off the estuarine mouth presented strong low frequency signal, with dominance of longshore orientation. Despite of the limitation of the near surface ADCP data, it was possible to observe the plume effects, inducing offshore currents.
DE: 4219 Continental shelf processes
DE: 4235 Estuarine processes
DE: 4546 Nearshore processes
DE: 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL
DE: 4855 Plankton
SC: Ocean Sciences [OS]
MN: 2005 Joint Assembly