A B S T R A C TThe contribution of the polluted São Vicente and Santos estuarine channels to the eutrophication of Santos bay was assessed through the quantification of instantaneous transport of salt, dissolved inorganic nitrogen (DIN) and phosphate, organic and inorganic matter (OSM and ISM) and chlorophyll-a (Chl-a), during dry (austral winter-August/ 1999) and rainy (austral summerJanuary/2000) seasons. Samplings were carried out during spring and neap tides, in flood and ebb phases, in two transversal sections at the mouths of the São Vicente and Santos channels. Instantaneous transport values generally indicated importation of salt to the estuarine channels, exportation of DIN to the bay, mainly as N-NH 4 , at a maximum rate of 1155.1 g s -1 during the rainy season; importation of phosphate during the dry season (maximum of 385 g s -1 ) and exportation of ISM, OSM and Chl-a during periods of greater freshwater discharge. These results demonstrate the great contribution made by the Santos and São Vicente estuaries to the eutrophication of Santos bay, especially in the rainy season. R E S U M OA contribuição dos canais estuarinos de Santos e São Vicente para a eutrofização da baía de Santos foi avaliada quantificando-se o transporte instantâneo de sal, fosfato e nitrogênio inorgânico dissolvido (NID), material em suspensão orgânico (MSO) e inorgânico (MSI) e clorofila-a, durante a estação seca (inverno austral-Agosto/1999) e chuvosa (verão austral-Janeiro/ 2000). As amostragens foram realizadas em períodos de sizígia e quadratura, durante as marés enchentes e vazantes, nas secções transversais das bocas dos canais de São Vicente e Santos. Os valores de transporte instantâneo obtidos durante o período de amostragem indicaram exportação de NID, principalmente sobre a forma de N-NH 4 (valor máximo de 1155,1 g s -1 ) na estação chuvosa; importação de fosfato durante a estação seca (máximo de 385,6 g s -1 ) e exportação de MSI, MSO e clorofila-a em períodos de maior contribuição fluvial. Estes resultados indicam uma importante contribuição dos canais estuarinos de Santos e São Vicente para a eutrofização da baía de Santos, especialmente durante o período chuvoso.

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Dissolved nutrients and phytoplankton distribution in the Bertioga Channel, Silo Paulo State, were studied over a neap and a spring tide during the austral winter of 1991. Tidal influence and freshwater flow were the main forcing agents on the water column structure, nutrient availability and phytoplankton distribution as pointed out by the principal component analysis. The channel was vertically stratified during neap tide, but almost fully homogeneous during spring tide, especially in the flood phase. The inner area of the channel had high nutrient concentrations (up to 25 txM ammonium) and low dissolved oxygen saturation (minimum 20%). Phytoplankton biomass, measured as chlorophyll-a concentration, was low (maximum, 4.5 mg m 3) considering the high nutrient availability. The highest chlorophyll-a levels were associated with waters of coastal origin and flood periods. The phytoplankton community was dominated by phytoflagellates but the contribution of diatoms became very significant during spring tide. The major microphytoplankton forms were Skeletonema costatum and Pseudonitzschia species. The noticeable presence of freshwater species (Pinnularia, Synedra and Scenedesmus species), indicated the important role of freshwater inflow in the composition of local phytoplankton community. Data suggest that the high flushing rates and hydrodynamic instability at Bertioga Channel accounted for the low phytoplankton biomass observed in the environment.

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Plankton community and hydrological conditions were assessed as a part of ao environmental diagnosis in São Sebastião Channel, before the building of a submarine outfall of produced water from the oil maritime terminal of PETR08RÁS. Samples were collected in twenty oceanographic stations located in the oil terminal neighboring area, during the springtime of 1991. Oissolved inorganic nutrients and chlorophyll-a concentrations observed indicate an oligo-mesotrophic environment. Phenols and sulfides were absent, 800 values, except for three sampling points, were characteristic of unpolluted environments, although oil and grease were found in half of the sampled stations. Phytoplankton and zooplankton communities presented high diversity and evenness indices for the entire area. Phytoplankton was dominated by phytoflagel1àtes and zooplankton was dominated by copepods, mostly Paracalanus quasimodo. Plankton community composition was similar to that from adjacent regions under low anthropogenic influence.

A B S T R A C TShort-term variability of nutrients, chlorophyll-a (Chl-a) and seston (TSS) concentrations were followed up at a fixed station in the Bertioga Channel (BC), Southeastern Brazil, over two full tidal cycles of neap and spring tides, during the winter of 1991. Simultaneous data on hydrographic structure, tidal level and currents allowed the computation of the net transport of those properties. Tidal advection and freshwater flow were the main forcing agents on the water column structure, nutrient availability and Chl-a distribution. Dissolved inorganic nitrogen and phosphate average values were high (16.88 and 0.98 µM, respectively, at neap tide and 10.18 and 0.77µM at spring tide). Despite N and P availability, Chl-a average values were low: 1.13 in the neap and 3.11 mg m -3 in the spring tide, suggesting that the renovation rate of BC waters limits phytoplankton accumulation inside the estuary. The highest Chl-a was associated with the entrance of saltier waters, while the high nutrient concentrations were associated with brackish waters. Nutrients were exported on both tides, TSS and Chl-a were exported on the spring tide and Chl-a was imported on the neap tide. The study of the main transport components indicated that this system is susceptible to the occasional introduction of pollutants from the coastal area, thus presenting a facet of potential fragility. R E S U M OVariações de curta escala das concentrações de nutrientes, clorofila-a (Cl-a) e séston foram acompanhadas em uma estação fixa no canal de Bertioga (CB), sudeste do Brasil, em dois ciclos completos de maré de quadratura e sizígia, no inverno de 1991. Dados simultâneos da estrutura hidrográfica, marés e correntes permitiram calcular o transporte resultante daquelas propriedades. A advecção por maré e o fluxo de água doce foram as principais forçantes da estrutura hidrográfica e da distribuição de nutrientes e Cl-a. As concentrações médias de NID e fosfato foram altas (respectivamente: 16,88 e 0,98 µM na quadratura e 10,18 e 0,77 µM na sizígia). Apesar da disponibilidade de N e P, os valores médios de Cl-a foram baixos: 1,13 mg m -3 (na quadratura) e 3,11 mg m -3 (sizígia), sugerindo que a alta taxa de renovação das águas do CB limitam o acúmulo de fitoplâncton. Os maiores valores de Cl-a relacionaram-se à entrada de águas costeiras enquanto que as altas concentrações de nutrientes foram relacionadas às águas salobras. Os nutrientes dissolvidos foram exportados em ambas as marés, séston e Cl-a foram exportados na sizígia e, na quadratura, a Cl-a foi importada. O estudo dos principais componentes do transporte indicou uma susceptibilidade desse sistema à introdução de poluentes oriundos da área costeira, revelando uma potencial fragilidade ambiental.