Marine pollution-environmental indicators in marine meiofauna from Brazil

Abstract

To assess the primary stresses that affect environmental quality, recent benthic foraminiferal distribution in Brazilian domestic outfalls of Baixada Santista, São Paulo State (Santos Bay, Long Beach, Guraujá Cove), close to oil refineries in Todos Santos Bay (BA), Guanabara Bay (RJ), and Sao Sebastião Channel, and from environments polluted by pesticides in Laguna (SC) were compared through foraminifera species in 250 sediment samples. In Santos Bay, living species of Buliminella elegantissima and Bolivina spp. reflect the large amount of organic substances exiting the sewers, however, the occurrence of large amounts of aerobic and anaerobic species seems to indicate that, while the eastern portion of the Santos Bay and the region near the outfall are probably subject to contamination, these environments are relatively well oxygenated due to high dynamic circulation in the Bay. Brackish rivers and mangroves in Santos Bay are populated by Arenoparrella mexicana, Haplophragmoides wilberti, Ammotium salsum, Gaudryina exillis, Miliammina fusca, Paratrochammina sp., P. clossi, Polysaccammina ipohalina, Siphotrochammina lobata, Warrenita palustris, Glomospira gordialis, Ammobaculites ssp., Trochammina inflata. Aerobic species in Long Beach are more abundant in the northern portion with higher densities being correlated with the distance to the outfall. In the Guaruja Cove, species of anaerobic environments are comparatively more abundant near the outfall output, and the occurrence of large concentrations of anaerobic and aerobic species in the western portion of the Guaruja Cove seems to reflect the North Eastern current system, which penetrates this portion of the Bay. Apparently, although there is evidence of contamination in this area, the system presents current conditions of relatively well-oxygenated environments. In Todos Santos Bay, Ammonia spp., Bolivina spp., Fursenkoina pontoni tolerate sediment with aliphatics, whereas Elphidium spp. decreases under the influence of petroleum-derived pollutants. In Guanabara Bay, Buliminella elegantissima, Bolivina striatula, Bulimmina elongata flourish under conditions of poorly oxygenated waters in organic enriched sediments. On the other hand, Quinqueloculina seminulum shows intolerance to poorly oxygenated bottom water, and Cassidulina subglobosa and Discorbis williamsoni are governed by lower temperature and higher salinities in the Bay’s entrance, showing marine influence capable of renewing waters. In São Sebastião Channel, most anaerobic species were alive, indicating that the density of organic matter is not yet affecting the fauna of foraminifera. The São Sebastião channel and Laguna estuarine system presented Buccella peruviana as a coldwater species showing the influence of Malvinas currents. In relation to the petroleum pollutant outfall in São Sebastião, fauna are distributed along a remarkable gradient related to the distance from the outfall. The dominance of Ammonia spp., Bolivina spp., Buliminella elegantisssima, and Fursenkoina pontoni in high organic sediments shows slight contamination. Miliamina fusca denotes the presence of freshwater, as well as its tolerance to polluted sediments. On the other hand, Hanzawaia boueana, Pseudononion atlanticum, Discorbis williamsoni, D. floridana, Quinqueloculina spp., Pararotalia cananeiaensis, Cassidulina subglobosa, Elphidium spp., Poreoponides lateralis, and Pyrgo sp. reflect high intensity marine currents. In Laguna, the presence of Buccella peruviana, Bolivia striatula, Cassidulina subglobosa, Pseudononion atlanticum, Saccamina sphaera, Quinqueloculina miletti, Q. patagonica, Ammonia tepida, and Elphidium poeyanum is an indicator of marine water intrusion. As fresh water indicators, Ammobaculites exigus, Gaudryina exillis, Ammotium salsum, and Miliammina fusca, together with the thecamoebians, inhabit environments with the highest freshwater input. It was also noted that M. fusca is the only species that tolerates pesticides contamination.