Biochemical and morphological responses in Ucides cordatus (Crustacea, Decapoda) as indicators of contamination status in mangroves and port areas from northern Brazil

The aims of this study were to analyze biochemical and morphological responses (glutathione S-transferase activity and branchial lesions) in Ucides cordatus (crabs) and to verify how the species is responding to environmental contamination in a port (potentially contaminated area) and mangrove (reference area; Amazon Coast, Maranhão, Brazil). Adult males were captured bimonthly for a period of 1 year. Higher GST activity (1.03 ± 0.07 μmol min^-1 mg protein^-1) was observed in crabs in the port when compared with those in the reference area (p < 0.05). The greatest number of branchial lesions (serious alterations) was recorded in crabs only in the port area. The GST activity increased until serious lesions appeared; after this limit, GST activity decreased dramatically to very low levels, thus resulting in irreversible lesions (lamella collapse). The mathematical model based on the two parameters evaluated in U. cordatus showed that the port area experienced substantial contamination impact, while the mangroves (reference area) presented moderate environmental quality.

A screening test based on hematological and histological biomarkers to evaluate the environmental impacts in tambaqui (Colossoma macropomum) from a protected area in Maranhão, Brazilian Amazon

Nowadays biomonitoring programs can benefit with mathematical models able to correlate biomarkers to monitor water pollution. The aim of this study was to develop a screening test based on hematological parameters and histological lesions in tambaqui (Colossoma macropomum), to allow the assessment of environmental impacts on fish inhabiting a protected area in Maranhão inside of Brazilian Amazon. Samples collected during three years (2012, 2013 and 2014) were grouped by season (dry and rainy) Water samples were also collected for physical chemistry analysis. Blood samples were stained with Acridine Orange to detect micronuclei and erythrocyte abnormalities. Gill tissues were stained with hematoxylin and counterstained with alcoholic eosin, and histopathological lesions were scored on a scale of 1-3, being 1 = minimal pathological importance, 2 = moderate pathological importance and 3 = marked pathological importance. A screening test for evaluating environmental impact was developed by fitting the measured data (necrosis, erythrocyte abnormalities, number of micronuclei) from tambaqui. A three-dimensional surface was fit to the empirical data. Our proposed model predicted the probability of necrosis (observed in euthanized animals) based on the numbers of micronuclei and abnormal erythrocytes (observed in blood samples from live animals) (correlation coefficient R = 0.89). The methodology could be applied for predicting contamination histories (chronic pollution that induces branchial lesions) in rivers using the micronucleus and erythrocyte abnormalities of the fishes (with a simple blood sample).