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In the Godineau River Estuary, located in Trinidad Island (off the northeast coast of Venezuela), were found 114 taxa of foraminifera and 17 of thecamoebians in the dead fauna. Most of the identified foraminiferal species were rare because they were transported from the Gulf of Paria to this estuary. The autochthonous foraminiferal assemblage was represented by several tropical estuarine species such as Ammonia tepida, Ammotium salsum, Arenoparrella mexicana, Cribroelphidium excavatum, Ammonia parkinsoniana, Haplophragmoides wilberti, Miliammina fusca and Ammotium cassis. The thecamoebians assemblages, found in the inner part of this estuary, were dominated by Cyclopyxis spp., Centropyxis spp., Difflugia corona and Difflugia urceolata. The relative abundance of the main species of foraminifera and thecamoebians were analyzed through Q-mode and R-mode cluster analyses. Statistical results revealed the presence of three different environments in the Godineau River Estuary related to different hydrodynamic conditions and more or less oceanic or fluvial influence. The first sector represents the most confined region of the estuary and was mainly composed by agglutinated foraminifera together with thecamoebians. The second sector was located in the middle part of the estuary and was associated with the presence of brackish waters. The third sector denotes the outermost part of the estuary characterized by the greatest hydrodynamic activity and highest oceanic influence within the estuary. This sector was marked by the occurrence of a large number typical-marine foraminifera species.

The detrended correspondence analysis (DCA) applied to the relative abundance of ostracoda species and physical-chemical, sedimentological and geochemical parameters allowed to identified four sectors in the estuary of the Arade River: Sector I - located between the mouth of estuary and Portimão City and is characterized by the largest number of species of ostracoda, higher salinity and pH, sandy sediment and higher protein concentration. This sector has the largest marine influence with high phytoplankton productivity; Sector II - located in the vicinity of Parchal City, it is characterized by the highest value of diversity H' and the occurrence of the species Leptocythere lacertosa, Herpetocypris helenae and Leptocythere porcellanea. In this sector was identified the highest concentration of sulfur and fine sediments; Sector III - located between Silves and Parchal cities, has the highest concentration of organic carbon, fine sediment and biopolymers (carbohydrates, lipids and proteins). In this sector were identified only the dominant species in the estuary (Loxoconcha elliptica, Cytherois fischeri e Leptocythere lacertosa); Section IV - located in the Silves City, this sector had the highest lipid content and the silt fraction of the whole estuary. The sectors identified in Arade River Estuary, this is characterized as the most confined where the effluents from Silves City are deposited. The DCA analysis showed that the Loxoconcha ellipitica is the most characteristic species of this sector, and it can be considered with a confined environments bioindicator. A análise de correspondência destendenciada (DCA) aplicada à abundância relativa das espécies de ostracodes e aos parâmetros físico-químicos, sedimentológicos e geoquímicos permitiu dividir o estuário do rio Arade em quatro setores: Setor I -- localiza-se entre a foz e a cidade de Portimão, que foi caracterizado pelo maior número de espécies de ostracodes, valores mais altos de salinidade e pH, sedimento arenoso e maior concentração de proteínas no sedimento. Este setor foi considerado com maior infuência marinha, alta produtividade fitoplanctônica; Setor II -- localizado nos arredores da cidade de Parchal, foi caracterizado pelo maior valor de diversidade H' e pela ocorrência das espécies Leptocythere lacertosa, Herpetocypris helenae e Leptocythere porcellanea. Neste setor foi identificada a maior concentração de enxofre e de sedimentos finos; Setor III -- localizado entre as cidades de Parchal e Silves, este setor apresentou grande concentração de carbono orgânico, sedimento fino e de biopolímeros (carboidratos, lipídios e proteinas). Neste setor foram identificadas somente as espécies dominantes do estuário (Loxoconcha elliptica, Cytherois fischeri e Leptocythere lacertosa); Setor IV -- localizado na cidade Silves, este setor apresentou a maior concentração de lipídios e da fração silte de todo o estuário. Dentre os setores identificados, este é o mais confinado, onde há deposição dos efluentes da cidade Silves. A análise em DCA demonstrou que a espécie Loxoconcha elliptica é a espécie mais característica deste setor e por isso, pode ser considerada como um bioindicador de ambientes confinados.

This study is based on the characterization of the sedimentary environment in selected sites, located in Aveiro canals and salt-pans, in the eastern-central and northern part of Aveiro Lagoon. Results of physicochemical parameters measured in water and sediment, as well as grain size, geochemical and microfaunal (benthic foraminifera) data are analyzed. The determinants factors of spatial and seasonal variability of living and dead foraminiferal assemblages were analyzed in two sampling periods, late summer and late winter, in order to study the response of these organisms to the impact caused by pollution and sazonal variation of physicochemical parameters. Biotic and abiotic results are analyzed to discriminate sites with different degree of environmental stress. The conditions of salinity, temperature, pH and Eh in the studied sites vary spatially and seasonally. The sediment in these locations is generally poorly oxygenated, suboxic or even anoxic a few millimeters below the surface. Some of the sites are affected by chemicals derived from industrial effluents and urban contaminants. The most polluted areas by heavy metals such as As, Cr, Cu and Zn are Porto de Salreu, Largo do Laranjo and some locals in the city of Aveiro. Foraminiferal assemblages in the studied sites integrate common lagoonal and estuarine euryhaline and eurythermic species, most of which tolerant to the oxygen reduction. The size of the living foraminiferal communities is reduced and their structure affected by increasing concentrations of heavy metals such as As, Cr, Cu and Zn, as well as by the high variability of environmental parameters such as low Eh, related to depressed levels of oxygen in the sediment, leading to the death of many species. The results also indicate a greater tolerance of some opportunistic species to the Pb enrichment, since the environment offer them abundance and quality of food.