Multiple metals and agricultural use affects oxidative stress biomarkers in freshwater Aegla crabs

Metals and agrochemicals are among the main aquatic contaminants, being able to trigger oxidative stress in exposed organisms. The objective of this work was to evaluate the correlation between the level of oxidative stress biomarkers in Aegla crabs (Crustacea, Anomura) with (i) the set of metals present in the streams sediment and (ii) with land uses of three hydrographic basins. The study was carried out in streams (≤ 2nd order) of hydrographic basins in southern Brazil (Basins of Rio Suzana, Rio Ligeirinho-Leãozinho and Rio Dourado). In these streams were quantified the land uses and Cu, Cr, Cd, Fe, Mn and Zn concentrations in the sediment. The enzymes Catalase (CAT) and Glutathione Reductase (GR), as well as the level of membrane lipid peroxidation (TBARS), were analyzed in adult females. The PCA analysis showed that the distribution of metals was different between the basins. Cd, Cr and Fe were correlated positively with CAT and negatively with TBARS and GR. The Dourado basin had the lowest concentrations of these three metals and the highest levels of TBARS. However, in Dourado basin there is predominance of agriculture land use, and TBARS was positively correlated with agricultural land use. Besides in Dourado basin, GR activity was higher than in the others basins, indicating a compensatory response in relation to CAT inhibition. The basins of Suzana and Ligeirinho-Leãozinho rivers had lower TBARS values, which may be due to the induction of CAT in response to metals accumulated in sediment. In summary, this work indicates that in the basins with a higher concentration of toxic metals there is an adaptive response of CAT induction, which reduces TBARS in Aegla. On the other hand, in the basin with lower metallic contamination, TBARS occurrence was primarily influenced by agricultural land use.

Characterization of oxidative stress biomarkers in a freshwater anomuran crab

In general, environmental responses at level of populations or communities are preceded by alterations at lower biological levels which can be efficiently detected by the analysis of biomarkers. We analyzed the oxidative biomarkers TBARS and Catalase in Aegla singularis, a freshwater crustacean highly sensitive to environmental changes. The objective was to address if are differences in these biomarkers related to the gender as well if they are influenced by seasonal or water physicochemical variables. The results showed differences in biomarkers profile related to the gender. In female crabs were not sensitive to seasonal variations throughout the study period. However, in males the biomarkers evaluated were higher in the winter as compared to remaining seasons and showed tendency of negative correlation with water temperature and pH. This study highlights that gender, seasonal variations and physicochemical variables can influence oxidative stress biomarkers in A. singularis. Female crabs probably are better suited as a model for biomarker application in environmental studies, because their insensibility to seasonal variations can facilitate the observations of responses related specifically to environmental disturbances.