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Toxic blooms of the cyanobacterium Microcystis aeruginosa, a microcystin producer, have been observed in the past two decades in the Patos Lagoon estuary (southern Brazil). This cyanobacterium reaches the estuary from northern waters and accumulates as toxic blooms in the shallow margins of the environment. Microcystins are phosphatase (PP1 and PP2A) inhibitors and cause animal death via alteration of the liver cell cytoskeletons and intrahepatic hemorrhage. The massive accumulation of toxic material affects the survival of several benthonic estuarine local organisms. The tanaidacea Kalliapseudes schubartii is a benthonic estuarine species which occurs at high densities throughout the year in mixohaline areas of the Patos Lagoon. This microcrustacean is of high ecological relevance and plays an important role in the estuarine food web, as it is consumed on a large scale by estuarine fish. This work verifies the acute toxicity of aqueous extracts of M. aeruginosa RST9501 and of sediments spiked with lyophilized material of the same strain on K. schubartii; it also evaluates the sublethal effects on tanaidacean oxygen consumption rates and glycogen levels under acute exposure to M. aeruginosa aqueous extracts. The strain M. aeruginosa RST9501 was cultured in BGN/2 medium. The aqueous extracts were prepared using the lyophilized material from the strain cultures. Acute tests were performed over 96 h at a salinity of 15, at six toxic concentrations, and resulted in an average 96-h LC50 of 1.44 mg ml(-1). The spiked sediment tests were performed with a 10-day duration, using the lyophilized material in three proportions of powder/sediment and showed an average LC50 of 1.79 mg ml(-1). Oxygen consumption was determined after 24 and 48 h of incubation in adult organisms exposed to sublethal aqueous extract concentrations and showed a significant increase at the highest concentrations. This suggests alterations in the organism's metabolism by exposure to the cyanobacterium extract. The glycogen levels were determined with a commercial kit (Glicox 500; DOLES Ltd.); after 24 and 48 h the dosages were administered in the same organisms utilized in the oxygen consumption test and did not demonstrate significant differences. The results demonstrate the possible risks of intoxication to which the natural populations of K. schubartii were exposed in the environment and emphasize the importance of studies involving sublethal concentrations of M. aeruginosa to other organisms of the trophic web in this aquatic system.

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O desempenho de dois kits comerciais de ensaios imunológicos (ELISA com anticorpos ligados a partículas magnéticas) foi avaliado para a quantificação de hidrocarbonetos em sedimentos estuarinos. O kit BTEX RaPID Assay ® foi utilizado para analisar hidrocarbonetos alifáticos e aromáticos leves, enquanto que o kit c-PAH RaPID Assay ® foi utilizado para hidrocarbonetos poliaromáticos carcinogênicos (≥ 4 anéis aromáticos). Os resultados foram validados comparando com análises feitas por cromatografia gasosa com detectores de ionização de chama (GC/DIC) e de espectrometria de massa (GC/EM). Foi observada uma boa correlação entre as técnicas (r 2 =0,68-0,97), estando a disparidade relacionada a diferenças na composição relativa de hidrocarbonetos que afeta a resposta dos anticorpos dos testes ELISA. De uma forma geral, os resultados obtidos com os kits ELISA foram comparáveis aos obtidos por cromatografia, confirmando a validade dessa técnica em protocolos de avaliação preliminar, visando o emprego de técnicas analíticas de alta resolução em amostras específicas.The performance of two commercially available enzyme-linked immunosorbent assay (ELISA) kits (with antibodies attached to magnetic particles) for quantification of hydrocarbons in estuarine sediments is described. The BTEX RaPID Assay ® was employed to analyse aliphatic and small aromatic hydrocarbons whilst the c-PAH RaPID Assay ® was used to analyse the carcinogenic (≥ 4 aromatic rings) polycyclic aromatic hydrocarbons. Results were validated by comparison with analyses by gas chromatography (GC)-Flame Ionisation Detection (FID) (with GC-MS confirmation). Correlations between the techniques were good with r 2 values ranging between 0.68 and 0.97. Disparity between immunoassay and GC techniques were related to differences in the relative compositions of the complex mixtures of hydrocarbons, which alter ELISA responses. Overall, results from the ELISA techniques are shown to compare well with those obtained by GC, confirming ELISA as a useful screening protocol to focus use of the more expensive and time consuming high resolution analytical techniques.Keywords: immunoassay, ELISA, hydrocarbons, PAHs, validation, sediment IntroductionAliphatic and aromatic hydrocarbons are amongst the most commonly detected contaminants in the aquatic environment, deriving from petroleum and combustion processes. Their ubiquity and frequently high concentrations creates environmental concern regarding ecotoxicological effects. Although a wealth of literature addresses these as important environmental pollutants, there is a weak link between chemical investigations and biological effect assessments using ecotoxicological methods. Often, time consuming chemical methods do not provide the response needed for rapid environmental assessments. However, immunoassay techniques have been directed towards measuring environmental contaminants.1-10 The most common format used for 775 Fillmann et al. Vol. 18, No. 4, 2007 environmental analyses is the ELISA (enzyme-linked immunosorbent ...

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