Short-term response of phytoplankton community to over-enrichment of nutrients in a well-preserved sub-tropical estuary

Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Univ Fed Sao Paulo, Dept Ciencias Mar, Av Almirante Saldanha da Gama 89, BR-11030400 Santos, SP, BrazilUniv Estado Rio De Janeiro, Fac Oceanog, Dept Oceanog Biol, Rua Sao Francisco Xavier 524, BR-20550900 Rio De Janeiro, RJ, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, Av Almirante Saldanha da Gama 89, BR-11030400 Santos, SP, BrazilWeb of Scienc

Short-term response of phytoplankton community to over-enrichment of nutrients in a well-preserved sub-tropical estuary

Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Univ Fed Sao Paulo, Dept Ciencias Mar, Av Almirante Saldanha da Gama 89, BR-11030400 Santos, SP, BrazilUniv Estado Rio De Janeiro, Fac Oceanog, Dept Oceanog Biol, Rua Sao Francisco Xavier 524, BR-20550900 Rio De Janeiro, RJ, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, Av Almirante Saldanha da Gama 89, BR-11030400 Santos, SP, BrazilWeb of Scienc

Comparative characterization of three Tetraselmis chui (Chlorophyta) strains as sources of nutraceuticals

Species of the genus Tetraselmis have traditionally been used as a valuable nutritional source in aquaculture for their high fatty acid content (5-10% dry weight). Their use in nutraceutical production for humans is growing worldwide. Among them, Tetraselmis chui is generally reported in the literature as rich in polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We evaluated the potential of three T. chui strains for the production of these nutraceuticals: the model strain CCAP 8/6, which is broadly used in the aquaculture industry due to its high PUFA content, and two strains (TCBG-1 and TCBG-2) isolated from Guanabara Bay (Rio de 28 Janeiro, Brazil). The two Brazilian strains grew faster than CCAP 8/6 with higher percentage of PUFAs (up to 70% of total FA at the exponential growth phase). They also produced unique fatty acids in significant quantities: TCBG-1 produced arachidonic acid (ARA) and EPA during the exponential phase (> 20% of total FA), while TCBG-2 produced these PUFAs in addition to DHA (>18% of total FA) at the late exponential phase. A two-stage growth system using co-cultures of the two Brazilian strains is proposed as an optimal model for PUFA production, based on their simultaneous scaling cultivation in photobioreactors. Furthermore, both strains are suitable candidates for upscaling in open systems in tropical regions since they are adapted to the environmental conditions in Guanabara Bay, where they form massive blooms by outcompeting other microalga

Short-term variability and transport of nutrients and Chlorophyll-a in Bertioga Channel, São Paulo State, Brazil

Variações 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 ¼M na quadratura e 10,18 e 0,77 ¼M 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.Short-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 ¼M, respectively, at neap tide and 10.18 and 0.77¼M 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

Intraspecific variation in alkaline phosphatase activity in Phaeodactylum tricornutum (Bacillariophyceae, Bohlin)

To describe potential intraspecific variation in phosphorus incorporation in two strains of Phaeodactylum tricornutum (Bohlin), Ub3 and Ub7, alkaline phosphatase (AP) activity was evaluated via enzyme-labeled fluorescence assay. Analysis using the probe ELF-97 (R) provides individual evaluation, and therefore can determine the nutritional status of inorganic phosphorus in phytoplanktonic cells. Bioassays compared the control treatment to both phosphate-enriched and phosphate-depleted treatments by varying only the phosphate concentration in the media. The P. tricornutum strains exhibited differences in their development when incubated in the phosphate-enriched media. The development of the Ub7 strain differed by exhibiting "luxury uptake" and utilization of organic phosphorus, and the alkaline phosphatase analysis indicated limitations of this clone under such conditions. The Ub7 strain showed higher AP activity, when compared to Ub3, in the P-enriched condition. P. tricornutum presented increases in AP activity and low variation in Surface/Volume ratio, by increasing biovolume and its maximum linear dimension, as strategies for phosphate incorporation. Our results highlight intraspecific differences in alkaline phosphatase activity, and hence differences in the incorporation of organic phosphorus, as the tested species regulated enzymatic activity under different external phosphate concentrations.Univ Estado Rio de Janeiro, Fac Oceanog, Lab Ecol & Cult Fitoplancton Marinho, BR-20550900 Rio De Janeiro, RJ, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, Campus Baixada Santista, BR-11030400 Santos, SP, BrazilInst Nacl Pesquisas Espaciais, Km 39, BR-12630000 Cachoeira Paulista, SP, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, Campus Baixada Santista, BR-11030400 Santos, SP, BrazilWeb of Scienc

Instantaneous transport of salt, nutrients, suspended matter and chlorophyll-a in the tropical estuarine system of Santos

A 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-NH4 (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.The 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 summer- January/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-NH4, 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