Biochemical and Histological Biomarkers in Crassostrea sp. (Bivalvia, Ostreidae) for Environmental Monitoring of a Neotropical Estuarine Area (São José Bay, Northeastern Brazil)

The marine and estuarine bony fishes (Teleostei) of the Golfão Maranhense on the eastern Amazon coast, northern Brazil

The Golfão Maranhense is an extensive estuarine complex that provides nursery grounds and other habitats for several fish species, as well as a wealth of resources for the coastal and estuarine artisanal fisheries of the Maranhão state, in northern Brazil. The present study provides a comprehensive inventory of marine and estuarine teleost fishes of the Golfão Maranhense based on field samplings, analyses of voucher specimens from local collections and literature data. This inventory presents a total of 163 species of teleosts belonging to 107 genera, 57 families and 27 orders. The order Perciformes prevailed in terms of richness (27 species), followed by Acanthuriformes, Carangiformes, Clupeiformes and Siluriformes. The most diverse family was Sciaenidae (19 species), followed by Carangidae, Ariidae, Engraulidae and Gerreidae. Among the 163 species recorded, 18 are new occurrences for the Golfão Maranhense. According to the IUCN Red List, seven species are classified as Vulnerable. Considering the official Brazilian list of threatened species, five species appear as Vulnerable and one - Epinephelus itajara - as Critically Endangered. Four of the recorded species (Butis koilomatodon, Trypauchen vagina, Omobranchus sewalli and Oreochromis niloticus) are exotic, and were probably introduced into the study area by shipping, fish farms or by the extension of their range along the Brazilian coast. The present study organizes, updates and expands the known and relatively limited data on the fish fauna of the Golfão Maranhense, highlighting the need for further research towards gathering data for conservation and management of the ichthyofauna of this important estuarine complex in the Northern Brazilian Coast.

Histopathology of chironomids exposed to fly ash and microplastics as a new biomarker of ecotoxicological assessment

In the last few decades, industrial pollution has gained extensive attention in terms of its effect on the aquatic environment. This imposes the need to develop sensitive biomarkers for early detection of pollutant toxicity in ecotoxicological assessment. The advantages of histopathological biomarkers are many, including quick reaction to the presence of contaminants, and the small number of individuals needed for efficient analysis. The present study analyzed the negative effect of lignite coal fly ash (LCFA) and microplastic particles (MPs) on Chironomus riparius, a suggested model organism by the Organization for Economic Cooperation and Development (OECD). This study aimed to perform histological analyses of larval tissues and target potential changes in treated groups that could serve as promising histopathological biomarkers of the contaminant's negative effects. Following that, other known sensitive sub-organismal biomarkers were analyzed and paired with the histopathological ones. Histological analysis of larvae showed a significantly decreased length of microvilli in midgut regions II and III in both treatments. Treatments with MPs affected oxidative stress parameters: thiobarbituric acid reactive substances (TBARS), advanced oxidation protein products (AOPP), superoxide dismutase (SOD), and hemoglobin levels, while LCFA significantly affected all tested sub-organismal biomarkers (DNA damage, levels of AOPP, SOD, and hemoglobin), except catalase (CAT) and TBARS. When observing histological slides, a significant shortage of brush border length in the posterior parts of the midgut was detected in all treatments. In the case of LCFA, the appearance of intensive vacuolization of digestive cells with inclusions resembling apoptotic bodies, in mentioned regions was also detected. This study demonstrated high sensitivity of brush border length to the MPs and LCFA exposure, complementary to other tested sub-organismal biomarkers. Revealing the great potential of this histopathological biomarker in ecotoxicological studies contributes to the international standard ecotoxicology assessment of emerging pollutants.

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.