RESUMO
Sampling deep-sea biota is a significant challenge because of the logistics required, in terms of vessels and equipment, to obtain minimally preserved specimens. Traditional methods (trawls, nets, and dredges) cause physical damage, stress, and even contamination during the process of removal from the seabed and their displacement through the water column to the surface. Preserving conditions similar to those found in situ is particularly important when the sampling strives to maintain living organisms and for analyses where contamination or degradation by stress or damage may interfere with the results. Therefore, for the sampling and storage of this biota with less interference, a polypropylene box was designed based on the model of Kellogg et al. (2009) incorporating adaptations to be used by a Remotely Operated Vehicle (ROV). This new device has been successfully used in eight oceanographic campaigns, adequately performing for sediment and biota sampling, including coral reef forming or framework species (Scleractinia), octocorals, associated fauna, and rhodoliths, at depths between 50 and 900 m.
Assuntos
Antozoários , Ecossistema , Animais , Recifes de Corais , Biota , ÁguaRESUMO
The fish embryo test (FET) is an alternative to the classic freshwater toxicity test used to assess environmental hazards and risks to fish. This test has been standardized and adopted by the Organization for Economic and Cooperation and Development (OECD). As salinity may affect the substances' toxicity, we describe the development of an alternative euryhaline test species for embryonic ecotoxicological tests: the Brazilian silverside Atherinella brasiliensis (Quoy & Gaimard, 1825). This species is broadly distributed along the coast of South America and is able to inhabit a broad range of environmental and saline conditions. Ours is the first study on the maintenance of a native South American species for natural reproduction and the generation of embryos for tests. The embryos used are transparent and possess fluorescent cells which have only been seen in a few species and which may be used as markers, making it an alternative assessment tool for the lethal and sublethal substances in marine and estuarine environments. We provide a detailed description and analysis of embryonic development under different salinities and temperatures. The embryos and larvae developed in similar ways at different salinities, however as temperatures increased, mortality also increased. We considered the effects of the reference toxicants Zn2+ and SDS using a protocol similar to the FET that was standardized for zebrafish. Brazilian silverside embryos are as sensitive as freshwater, or euryhaline fish, to the surfactant but are more resistant to metals prior to hatching. We were able to show the advantages of the Brazilian silverside as a model for a marine fish embryo test (FETm) with high levels of reproducibility and little contaminated waste.
RESUMO
Petroleum refineries generate large amounts of wastewaters, which can have acute/chronic toxicity toward aquatic organisms. Previous studies have shown that many contaminants can be responsible for this toxicity, among them ammonia, sulfide, cyanide, phenols and hydrocarbons. In the study reported herein, the cause of the chronic toxicity of a biotreated petroleum refinery wastewater was investigated by applying the TIE methodology using the microcrustacean Ceriodaphnia dubia. Five samples were analyzed, and the results suggest that copper is the primary toxicant, showing a strong correlation with wastewater toxicity in Phase III. Other metal contaminants, such as zinc and nickel, are present in the samples at toxic concentrations and these may also contribute (to a lesser degree) toward the toxicity. In the case of one sample, the toxicity was attributed to polycyclic aromatic hydrocarbons (PAHs), possibly benzo(a)pyrene, which was present at a concentration toxic to C. dubia. Although the values for the physicochemical parameters of the samples were below Brazilian environmental regulation limits (CONAMA 430), this was not sufficient to prevent chronic toxicity toward aquatic life, indicating that these limits are relatively high.
Assuntos
Cladocera/efeitos dos fármacos , Metais Pesados/toxicidade , Petróleo , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Águas Residuárias/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Metais Pesados/química , Hidrocarbonetos Policíclicos Aromáticos/química , Águas Residuárias/química , Poluentes Químicos da Água/químicaRESUMO
The impact of sediment coverage on two rhodolith-forming calcareous algae species collected at 100m water depth off the coast of Brazil was studied in an experimental flow-through system. Natural sediment mimicking drill cuttings with respect to size distribution was used. Sediment coverage and photosynthetic efficiency (maximum quantum yield of charge separation in photosystem II, ÏPSIImax) were measured as functions of light intensity, flow rate and added amount of sediment once a week for nine weeks. Statistical experimental design and multivariate data analysis provided statistically significant regression models which subsequently were used to establish exposure-response relationship for photosynthetic efficiency as function of sediment coverage. For example, at 70% sediment coverage the photosynthetic efficiency was reduced 50% after 1-2weeks of exposure, most likely due to reduced gas exchange. The exposure-response relationship can be used to establish threshold levels and impact categories for environmental monitoring.
Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/análise , Rodófitas/fisiologia , Poluentes da Água/análise , Brasil , Luz , Modelos Teóricos , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema IIRESUMO
Discharge of drill cuttings into the ocean during drilling of offshore oil wells can impact benthic communities through an increase in the concentrations of suspended particles in the water column and sedimentation of particles on the seafloor around the drilling installation. The present study assessed effects of water-based drill cuttings, barite, bentonite, and natural sediments on shallow- and deep-water calcareous algae in short-term (30 d) and long-term (90 d) experiments, using 2 species from Peregrino's oil field at Campos Basin, Brazil: Mesophyllum engelhartii and Lithothamnion sp. The results were compared with the shallow-water species Lithothamnion crispatum. Smothering and burial exposures were simulated. Oxygen production and fluorescence readings were recorded. Although less productive, M. engelhartii was as sensitive to stress as Lithothamnion sp. Mesophyllum engelhartii was sensitive to smothering by drill cuttings, barite, and bentonite after 60 d of exposure and was similarly affected by natural sediments after 90 d. These results indicate that smothering by sediments caused physical effects that might be attributable to partial light attenuation and partial restriction on gas exchange but did not kill the calcareous algae in the long term. However, 1-mo burial by either natural sediments or drill cuttings was sufficient after 60 d for both species to reduce oxygen production, and the algae were completely dead under both sources of sediments.