Pathogens and microorganisms in the mangrove oyster Crassostrea gasar cultivated in an estuarine environment in Northeast Brazil.

Estuaries are important ecosystems due to the ecological services they provide, acting as nurseries for many species of fish and invertebrates, and are also used as environments for the extraction and cultivation of mollusks. Oysters are animals that filter water to obtain oxygen and nutrients. In this process, they can bioaccumulate microorganisms and chemical substances in their tissues. The growth of mollusk culture in Northeastern Brazil requires the health identification of cultivated oysters through the quantification of the potentially harmful microbiota accumulated in the animals. Therefore, the present work aims to quantify and identify bacteria and possible pathogens found in the tissues of cultivated oysters and their culture waters. The Most Probable Number of Coliforms (MPN) in oysters and water were considered suitable according to the Brazilian current legislation, Vibrio sp. obtained low colonization and Salmonella sp. was not observed. The prevalence of microorganisms potentially pathogenic to oysters was 33.7%, highlighting metazoans and Nematopsis sp., however, the intensity of the infestation of these organisms was moderate. The low contamination of oysters demonstrates that this culture environment is promising for this activity. However, continuous environmental and sanitary monitoring is fundamental to guarantee the safety of the culture waters and the sustainability of aquaculture activities.

Aquatic pollutants are associated with reproductive alterations and genotoxicity in estuarine fish (Sciades herzbergii - Bloch, 1794) from the Amazon Equatorial Coast.

Estuaries are constantly subject to continuous environmental impacts of human activities, such as fisheries, port or industry, and domestic sewage, with fish being one of the most affected aquatic animals, reflecting the impacts directly on their bodies. Thus, the aim of this study was to carry out the biomonitoring of an estuary located on the Amazonian Equatorial Coast through analysis of PAHs (Polycyclic Aromatic Hydrocarbons) in the water, in addition to trace metals, histopathological alterations and analysis of erythrocyte micronuclei in Sciades herzbergii. S. herzbergii was used as a model species, due to its estuarine-resident behavior. Gonad and gill samples were subjected to histopathological evaluations. The quantification of trace metals was performed in samples of skeletal muscles of the animals collected, where concentrations of Lead (Pb), Copper (Cu), Zinc (Zn), Cadmium (Cd), Magnesium (Mg), Iron (Fe) and Aluminum (Al) were found. Except for Cadmium (Cd), all the concentrations were above the recommended limits. The PAHs analysis revealed the presence of Naphthalene and Acenaphthene in the water samples Histopathological and genotoxic analyses revealed of lesions in 100% of the study specimens. Thus, the histological and genotoxic alterations found in 100% of S. herzbergii specimens captured in São José Bay-MA are potentially associated with PAH concentrations present in the water. These results are potentially associated with the presence of PAH and trace metals, both in water and in animal tissues, inferring a general scenario of environmental contamination which directly implies a risk to the health and survival of the local biota. This study shows the relevance of continuous biomonitoring of estuarine ecosystems, in order to guide authorities regarding sewage management and ensure the evolutionary development of estuarine species, especially fishes of importance in the local cuisine, therefore related to human food security.