Search

Abstract Xenobiotics from oil tanker leaks and industrial discharges are amongst the main human impacts to confined coastal areas. We assessed the genotoxic responses to the water-soluble fraction of diesel oil in the polychaete Laeonereis culveri and the bivalve Anomalocardia flexuosa , two widespread benthic species in subtropical estuaries from the Southwestern Atlantic. We hypothesized that the highest responsiveness would be expressed by significantly different biomarkers responses between control and oil-impacted treatments. Responsiveness to diesel oil was investigated using an experimental design with two fixed factors (contaminant percentages and times of exposure). After exposure, we monitored the responses of the oxidative stress enzymes and performed micronuclei tests. Results were congruent for both species. Antioxidant defense of glutathione S-transferase and the induction of micronuclei and nuclear buds, the latter just for the bivalve, were significantly affected by polycyclic aromatic hydrocarbons, with significant increases on the seventh day of exposure and in the higher concentrations, compared to controls groups. We assessed the benefits and drawbacks of using each biomarker in laboratory experiments. Both species are indicators of early, and rapid responses to genotoxic contaminants in subtropical estuarine habitats. We suggest that the micronuclei frequency in A. flexuosa is a simple, fast and cheap test for genotoxicity in oil-impacted areas. Such early biomarkers are needed to develop better protocols for impact assessment and monitoring under real field conditions. Highlights • The genotoxicity of diesel oil was experimentally assessed in two benthic species. • Five concentrations of oil soluble fraction were crossed with three exposure times. • Similar response patterns of both species were observed for most biomarkers. • The contaminant induced GST activity and increased the frequency of micronuclei. • A. flexuosa and L. culveri may be sentinels for oil impact assessments in estuaries. [ABSTRACT FROM AUTHOR]

Bivalves and sediments were sampled from mangroves in the Pacific Coast of Colombia to evaluate the concentrations of the 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by U.S.EPA. Mangroves are highly vulnerable to anthropogenic activities, such as oil spills, which affect sediments and the organisms that depend on that ecosystem. Twelve samples of mangrove and non-mangrove (sandy) sediments and 20 samples of Anadara tuberculosa from mangrove were collected in marine and estuarine areas. In sediments and A. tuberculosa , the highest concentration of Ʃ16PAHs was found in estuarine mangroves close to the Rosario River mouth, ranging from 171.4 to 564.0 ng g−1 and 31.0 to 169.0 ng g−1, respectively. For the bivalve, the concentrations showed less variability than sediment, with 25% and 20% of bivalve samples exceeding the limits established by the European Regulatory Commission and Ministry of Health and Social Protection of Colombia, respectively, which can cause effects on people's health. The PAHs isomeric ratios determined in sediments indicated that these compounds were originated mainly from petrogenic sources. The PAHs profile reveals the dominance of 3 and 4 rings PAHs in sediments and dominance of 4 rings PAHs in bivalves. • The highest concentration of Ʃ16PAH in sediments was at the mouth area of the Tumaco Bay. • Petrogenic sources have a high impact in sediments from estuarine mangroves. • Not significant variation in the Ʃ16PAH concentrations was observed in bivalve samples. • Four- and three-ring PAHs were predominant in sediment and four in bivalve samples. [ABSTRACT FROM AUTHOR]