Baseline levels of oxidative stress biomarkers in species from a subtropical estuarine system (Paranaguá Bay, southern Brazil)

Abstract

Offshore petroleum exploration has increased the risks of oil spills in coastal tropical and subtropical habitats. Monitoring tools are needed to assess and protect environmental health. We determined baseline values of antioxidant biomarkers (CAT, SOD, GPx, GST, MDA) for five ecologically relevant species in a subtropical system in southern Brazil. Regional baseline levels are compared with literature data as a basis to eventually test their efficacy as post-spill monitoring tools. Differences in the antioxidant response among species, contamination, and seasons were tested using univariate and multivariate analyses. The bivalves Anomalocardia flexuosa and Crassostrea rhizophorae and the catfish Genidens genidens emerge as suitable sentinel species. Seasonality is the main factor accounting for biomarkers variability, and not background contamination level. However, interactions between season and contamination level are also significant, indicating that biomarkers respond to complex environmental settings, a fact that needs to be fully understood for designing proper monitoring programs.

Biomarkers responses of the clam Anomalocardia flexuosa in sediment toxicity bioassays using dredged materials from a semi-arid coastal system

“…In the study mentioned earlier, A. flexuosa and the oysters C. rhizophorae exposed to resuspended sediments in Mucuripe Bay also exhibited high activities of GR and GPx in their gills and digestive glands tissues (Moreira et al, 2019a). These results contrast with previous investigations that reported no changes in antioxidant responses (including GPx activity), in gills and digestive glands of A. flexuosa sampled in sites impacted by contamination sources in Paranagu a estuarine system (SW Brazil) (Sardi et al, 2016) and also in mudflats spiked with diesel oil in spills simulations (Sardi et al, 2017). Thus, we consider that clam responded to oxidative stress induced by dredged materials.…”

Effects of diesel oil and environmental quality on the enzymatic activities of a tropical estuarine catfish and implications for contamination assessment

“…Higher EROD and GST activities in winter have been correlated to the behavior of fish species from cold waters, when CYP450 are involved in preparing hormones and steroids for reproduction during the summer . Furthermore, the absence of seasonality for CAT and total CYP450 has been explained by taking into account the spatial variability induced by pollution status and runoff (Sardi et al, 2016;Azevedo et al, 2013). Although the present study did not sample fish during the summer period, results indicate that CAT enzymatic activity displayed higher peaks in winter (May and June 2012) following GST induction (June and July 2012), similarly to that discussed by Hayes et al (2005) regarding induction of α and μ GST classes by oxidative mechanisms.…”

“…However, biomarkers respond to complex environmental conditions, and enzymes may show different behaviors in different situations. For example, CAT was shown to be decreased in polluted areas in winter, but increased during summer, while GST has been reported as increased in polluted sites but similar during winter and summer (Sardi et al, 2016). Considering that such studies and the present work applied similar methodologies for enzymatic determinations, the results obtained herein were compared with values from the literature.…”

Omics approaches for conservation biology research on the bivalve Chamelea gallina

“…It is known for several bivalve species that biological parameters undergo seasonal variations in natural populations not exposed to contaminated conditions; hence, the differences shown from biomarker analyses in marine organisms employed as bioindicators of environmental quality might be related to a different physiological state [56][57][58] . The results obtained in the present study highlighted that in C. gallina, the biological responses utilized as biomarkers were modulated by biotic and abiotic seasonal factors, including salinity, temperature, food availability and reproductive status, confirming again the influence of these factors on biomarker modulation in sentinel marine species 56,59,60 .…”