RESUMO

The mussel Perna perna is an intertidal bivalve that is widely distributed, cultivated and consumed in South Africa, Brazil and Venezuela. Among marine resources, bivalve mollusks are one of the most impacted by anthropogenic pollution, as they can accumulate pathogenic bacteria and water pollutants. Hemocytes are molluscan defense cells, and their abundance and functions can be affected in response to contaminants, such as bacterial load. However, no previous study has investigated the immune response of P. perna hemocytes. The aim of this study was to evaluate several immune parameters in P. perna as indicators of fecal pollution in mussel hemolymph and in seawater. We collected mussels and adjacent seawater from beaches with different levels of fecal contamination in Rio de Janeiro state (Brazil): Vermelha Beach (VB); Icaraí Beach (IB); Urca Beach (UB); and Jurujuba Beach (JB). Hemocyte parameters (density, morphology, phagocytic activity and production of Reactive Oxygen Species - ROS) were evaluated using flow cytometry. We quantified Fecal Indicator Bacteria (FIB) in seawater by the multiple tubes technique for each beach and for hemolymph by the spread-plate technique. In agreement with historical evaluation of fecal contamination levels, UB presented the highest FIB abundance in seawater (thermotolerant coliforms, TEC = 1600 NMP 100 mL-1), whereas VB exhibited the lowest (TEC = 17 NMP 100 mL-1). UB mussels had six and eight times higher hemocyte density and phagocytic activity, respectively, than mussels from VB. Mussels from VB and IB presented a significantly lower number of total coliforms in hemolymph and a significantly higher relative internal complexity of hemocytes than those from UB and JB (p ≤ 0.01, PERMANOVA). ROS production by hemocytes was significantly lower in mussels from VB compared to those from JB (p = 0.04, ANOVA). Our results indicate a significant relationship between the level of fecal contamination in aquatic environments and the immune response of mussel hemocytes. Immune-related parameters may therefore be useful as indicators of bivalve health and environmental quality. Our flow cytometric analysis of P. perna hemocytes represents a new approach for studying Perna perna biology and might represent a novel tool for measuring organic pollution and water quality.

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A bacterial consortium was selected in the presence of Cu from sediment samples taken from Sepetiba Bay, Brazil, which is a site historically contaminated by metals. Bacteria were exposed to 0, 1, 6, 12.5, 25 and 50µg·mL(-1) Cu, Pb and Cu+Pb for 11days of bioassay. Results showed Alcanivorax dominance (81%) and cell counts of 10(8)cells·mL(-1). However, a reduction in dehydrogenase activity was observed from the fifth day of exposure for all Cu, Pb, and Cu+Pb concentrations tested. Esterase activity tended to increase, indicating higher energy demand to complete the bacterial lifecycle. Pb concentrations in the filtered culture medium (0.2µm) were below the detection limit, indicating biosorption, whereas concentrations of Cu were close to the tested concentrations, indicative of efflux. Results suggest the need for biomarkers, such as esterase and dehydrogenase enzymatic activity, in the assessment of resistance and tolerance of communities previously exposed to stressors.

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Ciliates are an essential component of microbial food webs, connecting biomass production to higher trophic levels and providing substrates for bacterial growth. Bacteria are widespread in sea sediment and the first to metabolize organic matter. Heavy metals are toxic and bind to particulate organic matter. This work aims to study the influence of heavy metals (Zn and Cu) on D. appendiculata and their naturally associated bacteria, both from Guanabara Bay during 96 h bioassay with 0, 0.001, 0.009, 0.05, 0.1 mg L-1 and maximum concentration stipulated by CONAMA 357 (Zn 5.0; Cu 1.0 mg L-1). It was analyzed for tolerance, resistance and biomass production. In Zn control, ciliate produced 1.24x102-2.47x103 μg C cm-3 (0-96 h), with 0.009 mg Zn L-1 reaches 2.49x102-1.93x103 μg C cm-3 (0-96 h). Their naturally associated bacteria, in Zn control, produced 5.0x10-2-5.67x10-2 μg C cm-3 (0-96 h), with 0.1 mg Zn L-1 4.87x10-2-8.38x10-2 μg C cm-3 (0-96 h). In Cu control, D. appendiculata produced 1.04x102-3.12x102 μg C cm-3 (0-96 h), with 0.009 mg Cu L-1 biomass was 8.31x101-7.27x10-2 μg C cm-3 (0-96 h) and with CONAMA concentration was below detection level. Their naturally associated bacteria, in Cu control, produced 1.20x10-2-5.14x10-2 μg C cm-3 (0-96 h) and with 0.1 mg Cu L-1 7.40x10-4-3.81x10-2 μg C cm-3 (0-96 h), with CONAMA concentration 5.14x10-2 μg C cm-3 (96 h). D. appendiculata are tolerant to 0.09 mg L-1 and resistant to 0.1 mg L-1 after 24 h to Zn-Cu and LD50 stipulated was 1.17 (Zn) 0.90 (Cu) mg L-1. Microbial loop was functional in low concentration of Zn and Cu, but their diversity in nature was affected.(AU)

Assuntos

RESUMO

Ciliates are an essential component of microbial food webs, connecting biomass production to higher trophic levels and providing substrates for bacterial growth. Bacteria are widespread in sea sediment and the first to metabolize organic matter. Heavy metals are toxic and bind to particulate organic matter. This work aims to study the influence of heavy metals (Zn and Cu) on D. appendiculata and their naturally associated bacteria, both from Guanabara Bay during 96 h bioassay with 0, 0.001, 0.009, 0.05, 0.1 mg L-1 and maximum concentration stipulated by CONAMA 357 (Zn 5.0; Cu 1.0 mg L-1). It was analyzed for tolerance, resistance and biomass production. In Zn control, ciliate produced 1.24x102-2.47x103 μg C cm-3 (0-96 h), with 0.009 mg Zn L-1 reaches 2.49x102-1.93x103 μg C cm-3 (0-96 h). Their naturally associated bacteria, in Zn control, produced 5.0x10-2-5.67x10-2 μg C cm-3 (0-96 h), with 0.1 mg Zn L-1 4.87x10-2-8.38x10-2 μg C cm-3 (0-96 h). In Cu control, D. appendiculata produced 1.04x102-3.12x102 μg C cm-3 (0-96 h), with 0.009 mg Cu L-1 biomass was 8.31x101-7.27x10-2 μg C cm-3 (0-96 h) and with CONAMA concentration was below detection level. Their naturally associated bacteria, in Cu control, produced 1.20x10-2-5.14x10-2 μg C cm-3 (0-96 h) and with 0.1 mg Cu L-1 7.40x10-4-3.81x10-2 μg C cm-3 (0-96 h), with CONAMA concentration 5.14x10-2 μg C cm-3 (96 h). D. appendiculata are tolerant to 0.09 mg L-1 and resistant to 0.1 mg L-1 after 24 h to Zn-Cu and LD50 stipulated was 1.17 (Zn) 0.90 (Cu) mg L-1. Microbial loop was functional in low concentration of Zn and Cu, but their diversity in nature was affected.

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The aim of this work was to quantify the biopolymers associated to esterase enzymes and identify bacterial respiratory activity in four cores collected in Suruí Mangrove, Guanabara Bay - RJ. Biopolymer concentration was 1000 times lower than previously reported in the literature, indicating the need for creating and establishing eutrophication indicative rates and records compatible with tropical coastal systems. The biochemical representative relationships in the cores were equivalent to those from studies on coastal marine environments made in the Northern Hemisphere. The esterase enzymes in the sediment proved efficient in the mineralization of biopolymers, even with preferentially anaerobic metabolic physiology. Despite the lack of incipient geomicrobiological studies, the results highlighted the possible application of microbiology to a better understanding of geological processes.

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The present study aimed to evaluate the water quality of the Icaraí Sewage Outfall (ISEO) area. Sampling was conducted during winter and summer, and water samples were analyzed for dissolved oxygen, pH, temperature, salinity, dissolved inorganic nutrients (DIN), seston, particulate organic matter (POM), and pigments. Results showed that the water chemistry of the area suffers temporal and spatial variation. Great variability was also seen in the C:N:P ratios of POM (August, 112:30:1; December, 59:11:1) and in the DIN concentrations. Chlorophyll-a and ammonium concentrations (4.5 µg L-1 - 71.2 µg L-1, and 0.20 µM - 52,6 µM, respectively) characterized the ISEO area as eutrophic. The dispersal of the material was not effective under certain oceanographic conditions.

O presente estudo teve por objetivo avaliar a qualidade da água na área do Emissário de Esgoto de Icaraí (ISEO). A amostragem foi realizada durante o inverno e o verão, e as amostras de água foram analisada quanto ao oxigênio dissolvido, pH, temperatura, salinidade, nutrientes inorgânicos dissolvidos (NID), seston, matéria orgânica particulada (MOP) e pigmentos. Os resultados mostraram que a química da água apresenta variações temporal e espacial. Grande variabilidade foi também observada nas razões C:N:P do MOP (Agosto, 112:30:1; Dezembro, 59:11:1) e nas concentrações de NID. As concentrações de clorofila-a e amônia (4.5 µg L-1 - 71.2 µg L-1, e 0.20 µM - 52,6 µM, respectivamente) caracterizam a área do ISEO como eutrófica. A dispersão do material não é efetiva em certas condições oceanográficas.