Quality assessment of two ecologically important ecosystems in the south coast of Portugal-oxidative stress biomarkers and proteomic analysis in Nereis diversicolor

Abstract

Aquatic environments in the south of Portugal, like estuaries and marshes, support vital habitats for organisms and have their environmental situation critically dependent on the contributions of pollutant substances. The evaluation of contaminant impacts on marine organis ms and consequent quality of the coastal zone is crucial and requires efficient analytical methodologies combined with new tools. Mudflat sediments are the definitive sink for most of the chemicals introduced in aquatic environments by anthropogenic sources. Consequently, benthic species like the polychaete Nereis diversicolor that live in close contact with sediments are particularly exposed to chemical stress. In this study, the environmental quality of two important aquatic ecosystems of south of Portugal (Ria Formosa Lagoon and Guadiana Estuary) was assessed carrying out an integrated approach that combined conventional oxidative stress biomarkers (SOD, CAT, GPX, and LPO) with proteomic analysis. Polychaetes were collected in the Ria Formosa and in the Guadiana Estuary, in two winter periods (2007 and 2010). The biomarker approach indicated site and period related differences , showing a slight improvement of one site in the Ria Formosa and a decline in the other. The Guadiana Estuary presented a higher oxidative stress level for polychaetes although not markedly different between winters. As for proteomic analysis, several significant differences were detected in protein expression signatures between sites. The highest changes in protein expression profi les (PEPs) corresponded to spots from the Guadiana Estuary possibly reflecting differences between contaminant loads as well as their interactions in complex mixtures. The comparison of PEPs through time could lead to the development of new biomarkers to b e used in environmental quality assessment and its integration with biomarker responses in N. diversicolor can be a useful tool for marine pollution monitoring in these ecosystems