ABSTRACT: The understanding of the differences between living (L) and dead (D) benthic foraminiferal assemblages and all the factors that might lead their distribution should be a key to characterize the environmental and paleoenvironmental changes accurately. Population dynamics and dissimilarities of biological nature (the differences in turnover rate and seasonal alterations in standing stock) can cause significant divergences between the L and D foraminiferal assemblages. This study compares L and D foraminifera to evaluate the sediment quality of the Brazilian Saquarema Lagoon System (SLS) using biogeochemical proxies and predict how coastal ecosystems are responding to the combined effects of eutrophication and pollution pressure and areas where the paleoenvironmental studies can be performed. The SLS is a transitional environment where total organic carbon, proteins, and dissolved oxygen are the main factors controlling the distribution of foraminiferal assemblage. The high values of biopolymers (carbohydrates, lipids, and proteins) in SLS indicate a very impacted environment with long water residence time. The low values of species richness, Shannon-Weaver diversity, and evenness for both L and D foraminiferal assemblages are a consequence of fluctuating conditions in the SLS. Due to low salinities, agglutinated species and Quinqueloculina seminula can occur in the most confined areas, and Ammonia parkinsoniana, Cribroelphidium excavatum, Cribroelphidium poeyanum, and Elphidium gunteri characterized the area with the highest marine influence. Although in most of the SLS the taphonomic processes modified the original assemblage, in some regions the thanatocoenosis corresponds to the biocenosis. These areas can be considered the most suitable for future paleoenvironmental and paleoclimatic studies.

A distribuição de compostos aromáticos selecionados e a microbiologia foram avaliados em sedimentos superficiais do Manguezal de Suruí, Baía de Guanabara. Amostras foram coletadas em 23 pontos e determinados a granulometria, matéria orgânica, compostos aromáticos, atividade microbiológica, biopolímeros e a topografia. A concentração dos compostos aromáticos foi distribuída em manchas por todo o manguezal e sua concentração total mais elevada foi encontrada na área central do manguezal. A granulometria diferiu da maioria dos manguezais, uma vez que no Manguezal de Suruí existem chernies nas bordas e na frente dos manguezais e areia através da superfície inteira, impedindo o relacionamento entre granulometria e os hidrocarbonetos. Uma média de 10% p/p da matéria orgânica foi obtida e os biopolímeros apresentaram concentrações elevadas, especialmente na área central e fundo do Manguezal. Os biopolímeros se distribuíram em altas concentrações. A presença de finos sedimentos é fator importante na acumulação de hidrocarbonetos. Na concentração elevada de matéria orgânica e de biopolímeros, topografia com chernies e as raízes que protegem os manguezais, áreas mais calmas são criadas, com depósito do material transportado pela ação das ondas. Comparadas às distribuições globais, as concentrações das substâncias aromáticas neste manguezal podem ser classificadas de moderadas a elevadas, demonstrando que a área estudada está altamente impactada.

The distribution of selected aromatic compounds and microbiology were assessed in superficial sediments from Suruí Mangrove, Guanabara Bay. Samples were collected at 23 stations, and particle size, organic matter, aromatic compounds, microbiology activity, biopolymers, and topography were determined. The concentration of aromatic compounds was distributed in patches over the entire mangrove, and their highest total concentration was determinated in the mangrove's central area. Particle size differed from most mangroves in that Suruí Mangrove has chernies on the edges and in front of the mangrove, and sand across the whole surface, which hampers the relationship between particle size and hydrocarbons. An average @ 10% p/p of organic matter was obtained, and biopolymers presented high concentrations, especially in the central and back areas of the mangrove. The biopolymers were distributed in high concentrations. The presence of fine sediments is an important factor in hydrocarbon accumulation. With high concentration of organic matter and biopolymers, and the topography with chernies and roots protecting the mangrove, calmer areas are created with the deposition of material transported by wave action. Compared to global distributions, concentrations of aromatic compounds in Suruí Mangrove may be classified from moderate to high, showing that the studied area is highly impacted.