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

Efeitos ambientais da disposição oceânica de esgotos por meio de emissários submarinos: Uma revisão

Oceanic disposal systems of domestic sewage, or submarine sewage outfalls, have been historically used around the world as a solution for urban effluents, in special due to economic aspects. However, release into the ocean, in shallow or deep waters, may induce a set of negative environmental impacts, as eutrophication, toxic algal blooms, pathogenic microorganisms introduction and contamination by chemical substances which are capable of causing toxic effects to the biota and bioaccumulation. Thus, the release of untreated sewage into the sea does not constitute an adequate environmental practice; then, urban effluents should be treated in order to remove nutrients, contaminants and pathogenic organisms and avoid environmental degradation

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

ABSTRACT 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

Monitoring of phytoplankton in a subtropical estuarine system through traditional taxonomic, functional diversity and microscopy-imaged-based classification tools.

12th International Phycological Congress, 2021 Também disponível em: (2021) 12th International Phycological Congress, Phycologia, 60:sup1, 74-74, ISSN: 0031-8884 DOI: 10.1080/00318884.2021.1922050Estuarine systems are under human activities pressure that may lead to changes in the structure of planktonic community. Given its importance as the basis of food webs and their rapid responses to environmental changes, phytoplankton is fundamental to understanding the effects of these changes on the general plankton community. The Santos Estuarine System (SES), Brazil, receives a high load of pollutants from petrochemical and fertilizer industries, as well as hosts one of the largest ports in Latin America. The present study aims to establish the bases for the implementation of long-term monitoring programs in this ecosystem combining classical monitoring methods (variation of chlorophyll biomass and taxonomic composition), with methodologies based on functional diversity (Convex hull) and on Microscopy-Imaged-based Classification Tools of plankton. Considering previous dataset from SES, computer vision techniques were employed to perform steps of object identification, filtering and feature extraction in order to obtain the final dataset. The developed software is open-source and available under the MIT license. From March 2020 (except in April and May due to COVID-19 pandemic), monthly surveys are being performed in four stations through the navigation channel of SES. Preliminary results showed dominance of filamentous cyanobacteria during raining/freshwater-influence periods and of diatoms under brackish and seawater-influence conditions. Salinity gradient was also a stressor condition resulting in changes in functional diversity index (FDis, FEve and FRic). Microscopy-Imaged-based Classification first results obtained a mean accuracy of 83.88% considering 4 classes, and 76.67% considering 13 classes.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP: 2018/25816-