Biomarcadores em brânquias e Hepatopâncreas de Ucides Cordatus Linnaeus (1873) (crustacea: decapoda) para o monitoramento de impactos antrópicos na ilha de São luís, Maranhão, Brasil

Abstract

Biomonitoring studies with biomonitor species suitable for the analysis of histological biomarkers (in organs such as gills and hepatopancreas) have been considered important in the assessment of impacted environments. Thus, this study aimed to evaluate lesions in gills and hepatopancreas of Ucides cordatus, as indicative of anthropic impacts on São Luís Island, Maranhão. Crabs were collected by the braceamento technique with the help of a professional collector in two areas, one in São José Bay: Raposa (with less impact) and Porto Grande Baía de São Marcos (potentially impacted area). In the laboratory, the biometric data of each crab specimen were obtained and the specimens were dissected to remove and fix the gills and hepatopancreas in Davidson's solution for 24 hours. Tissue samples were submitted to the standard histological technique, where they were dehydrated in increasing series of alcohols, diaphanized in xylene, impregnated and embedded in paraffin. Then, 5 micrometer-thick cross-sections were stained with Hematoxylin and Eosin and the slides were analyzed under a light microscope. The biometric data of the crabs in the two areas were expressed as means and standard deviation. The data showed significant gill and liver lesions in crabs from both areas. The main lesions found for the gills were rupture of the pilaster cells; deformation of the marginal channel and necrosis in both rainy and dry seasons. The most observed liver lesions were lumen deformation, vacuolated B cells, pyknotic nuclei and necrosis, also in both seasons. The averages of carapace width and length show that crabs from Raposa (less impacted area) were smaller than crabs from potentially impacted area, in both seasonal periods, however, they also did not show significant differences between them (p>0.05). The Bray-Curtis index for the gill alterations of U. cordatus for the dry and rainy season showed for both regions a grouping greater than 0.9 (or 90%) of lesions such as rupture of pilaster cells and deformation of the marginal canal; the necrosis lesion was grouped hierarchically forming the set of “most frequent lesions”. For liver lesions, it was found that the data for crabs from the Raposa region show similarity (>80%) in the dry season and (>70%) for the rainy season, gathering the lesions pyknotic nuclei, vacuolated B cells, lumen and necrosis; for the Porto Grande region, the cluster indicated a grouping (>80%) for both seasonal periods, bringing together necrosis lesions, lumen deformation, vacuolated B cells and pyknotic nuclei showing these lesions in both regions as the set of lesions more frequently. The altered biological responses (gill and liver changes in U. cordatus) prove that these crabs are subjected to stress levels that are compromising the crabs' vital functions