This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to metals enrichment.

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Clemente, I.M.M.M.; da Silva, F.S.; Laut, L.L.M.; Frontalini, F.; da Costa, V.L.; da Conceiçã o Rodrigues, M.A.; Pereira, E.; Bergamaschi, S.; Filho, J.G.M., and Martins, M.

2016. Ecological status evaluation of Itaipu Lagoon (Niterói) based on biochemical composition of organic matter. Journal of Sedimentary Environments, 1(3): 297-315. AbstractThe variety of approaches for assessing the trophic environmental state indicates that there is a strong need for the identification of new and possibly integrated ecological descriptors in coastal marine areas. These approaches would be able to capture relevant variables associated with the eutrophication process, and would be reliable, applicable and valid worldwide. The main objective of this study was to provide evidence that the quantity of total organic carbon (TOC), total sulfur (TS) and biopolymeric carbon (BPC) is useful proxies to evaluate the benthic trophic status in transitional marine environments. Sediment samples collected in Itaipu Lagoon, a Brazilian coastal system of the State of Rio de Janeiro, were analyzed in this study. Geochemical data, such as TOC, TS and BPC concentrations, including proteins (PTN), carbohydrates (CHO) and lipids (LIP), are combined with additional environmental parameters of the bottom water measured in in Itaipu Lagoon. The analysis of quantity and quality of organic matter (OM) allowed the identification of three distinct regions in Itaipu Lagoon: an inner and impacted zone characterized by sediment particularly enriched in TOC, with lower quality of OM most probably provided by the contaminated effluents and rivers runoff; an outer-less impacted lagoonal area with relatively low TOC content where the highest values of BPC/TOC and PTN/TOC are indicative of the presence of OM with high nutritional quality; and an intermediate area characterized by transitional features between the two previously described. The organic matter accumulation depends on the hydrodynamic conditions mostly governed by tidal currents. The quality of organic matter seems to be mainly influenced by municipal effluents, rivers inputs and mangroves contributions as well as by the autochthonous lagoonal biological productivity. Results of this work indicate that the inner zone of Itaipu Lagoon is being affected by eutrophication.

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