Este trabalho reúne informações disponíveis de variávies ambientais que permitem realizar uma avaliação das condições hidrodinâmicas da enseada da Armação de Itapocoroy. Dados de velocidade e direção de correntes, maré, vento, salinidade, temperatura, turbidez e a batimetria foram obtidos em diferentes ocasiões, porém em conjunto permitem elaborar um quadro preliminar da capacidade de suporte deste ambiente para manter a atividade de cultivo de moluscos marinhos. A taxa de renovação de água é da ordem de alguns dias, e a proximidade da desembocadura do estuário do Rio Itajaí-açu faz com que a pluma deste regularmente avance para o interior da enseada. A ação ocasional de ondas de tempestade de leste, juntamente com correntes devido ao vento e à maré, atuam na remoção de detritos gerados pelos cultivos.

ABSTRACT. The water level in the lower Paraíba do Sul river estuary was assessed in order to evaluate the effects of the astronomical tide co-oscillation, river discharge and meteorological events. Water level data was recorded hourly from October 2000 until February 2003 at a gauge station nearby the estuarine inlet. The water level is controlled mainly by the astronomical tide co-oscillation during periods of low river discharge, and eventually by meteorological tides. Even during periods of higher river discharge the water level is controlled by astronomical co-oscillation, although during low tide phase the river discharge effects are observable. During periods of extreme high discharge the low frequency water level is mainly driven by the river inflow. The tidal wave was mostly symmetrical during the low river discharge periods, and asymmetries were observed during meteorological events, with shorter flood and longer ebbs. Although, such effects were not corroborated by astronomical tidal constituents M 2 and M 4 relationship, which suggests ebb dominance. Stronger distortions were observed during high discharge periods, with tide attenuation either at neap as in spring tide periods. During these periods the asymmetries were corroborated by M 2 and M 4 relationship.Keywords: tidal asymmetry, meteorological tides, river discharge. RESUMO.A variabilidade do nível daágua no baixo estuário do rio Paraíba do Sul foi estudada para avaliar os efeitos da co-oscilação da maré astronômica, descarga fluvial e de eventos meteorológicos. Dados de nível daágua foram registrados em intervalos horários para o período entre outubro de 2000 até fevereiro de 2003 em uma estação localizada próximoà desembocadura do estuário. Foi observado que durante os eventos de descarga fluvial baixa os níveis deágua do estuário oscilam principalmente em função da co-oscilação da maré astronômica e eventualmente por marés meteorológicas. Durante períodos de descarga fluvial alta o nível daágua de preamar no baixo estuárioé dominado pela co-oscilação, enquanto que nas baixa-maresé influenciado pela descarga fluvial. Em períodos de descarga fluvial muito alta o estuário passa a receber a influência tanto da descarga fluvial quanto da maré astronômica nas oscilações do nível. Em períodos de baixa descarga quase não houve modificação na onda de maré, sendo observada pequena assimetria no sentido de vazante. Ainda em baixa descarga, eventos de maré meteorológica produzem distorções e assimetrias, com o tempo de subida menor que o de descida, gerando correntes mais fortes no sentido de enchente. Contudo, isto não pôde ser confirmado com a relação de fase entre M 2 e M 4 , que sugeriu domínio de vazante. A descarga fluvial alta causou fortes distorções na onda de maré em períodos de quadratura e uma atenuação considerável nas amplitudes tanto de sizígia como de quadratura, com assimetrias no sentido de vazante corroboradas pela relação de fase entre M 2 e M 4 .Palavras-chave: assimetria de maré, marés meteorológicas, descarga fluvial.

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The region of fluvial influence (ROFI) of Itajaí-Açu River was assessed through fourteen surveys covering thirty sampling stations in a radial shape with origin in the estuarine inlet. The total sampled area was of 100 km 2 , with depth ranging from 6 to 25 m, and until 10 Km offshore. The surveys were nearly monthly, from October 2002 to December 2003. The variables collected were salinity, temperature, suspended particulate matter, dissolved oxygen, chlorophyll a, picoplankton (autothrophic and heterothrophic) and zooplankton. River discharge and meteorological data were also obtained to help in the general characterization. The results indicated that in terms of averaged values of each variable, the sampling area is poorly related with the river discharge, or in other words, the sampling area is wider than the ROFI. Only salinity showed reasonably agreement with river discharge, although during the winter the region is affected by the Plata estuarine front. Further analysis on the data gathered must cope with spatial variability, either horizontal, e.g., plume dispersion, as vertical, e.g., plume buoyancy flow.

The Capibaribe Estuary is a water body that crosses the Recife Metropolitan Area (RMA), one of the largest population centers in Brazil, and causes large pollutant loads and poor water quality. The fresh water inflow of wastewater from the RMA can account for three times the volume of the river discharge during the low discharge period. This article assesses the hydrodynamics and potential transport of particulate and dissolved scalars in this estuary. A field experiment was conducted to record the water level, current velocity, salinity, temperature and suspended particulate matter (SPM) contents during a full semi-diurnal tidal cycle. This experiment was performed during low river discharge and spring tide conditions. The estuary showed a partially mixed circulation pattern. The residual transport of water and salt were up estuary, while the SPM residual transport was down estuary. The former were understood as the effect of the residual circulation around the islands, while the latter was interpreted as a morphological factor inducing greater resuspension during the ebb, despite the symmetrical ebb and flood currents. This mechanism may transport SPM to the inner shelf, even under tide-dominated conditions when the opposite would be expected.