Ecological Indicators 63 (2016) 209–218 Contents lists available at ScienceDirect Ecological Indicators j o ur na l ho me page: www.elsevier.com/locate/ecolind Fatty acids’ profiles as indicators of stress induced by of a common herbicide on two marine bivalves species: Cerastoderma edule (Linnaeus, 1758) and Scrobicularia plana (da Costa, 1778) A.M.M. Gonc ¸ alves a,b,∗ , A.F. Mesquita b , T. Verdelhos a , J.A.P. Coutinho c , J.C. Marques a , F. Gonc ¸ alves b a IMAR (Marine and Environmental Research Centre) & MARE (Marine and Environmental Sciences Centre), Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal b Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal c CICECO, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal a r t i c l e i n f o Article history: Received 26 September 2015 Received in revised form 1 December 2015 Accepted 3 December 2015 Keywords: Marine bivalves Fatty acids Herbicide effects Food quality a b s t r a c t In Europe, mainly the Mediterranean region, intensive use of fertilizers and pesticides has been recorded over the past 30 years, exceeding, in some cases, the limits of contamination authorized by the European Union. The intensive use of pollutants in fields near ecological coastal wetlands has led to implementation of pesticide monitoring programs to recover aquatic systems such as the Mondego estuary (Figueira da Foz, Portugal). According to information from the agricultural cooperatives of the Mondego valley, Primextra ® Gold TZ is the most-used herbicide in corn crop fields. Biomarkers, such fatty acids (FAs), proved to be new and potentially powerful tools to detect, illustrate, and evaluate exposure to and the effects of contamination hazards. They play important roles in establishing neural levels in organisms’ biochemical and physiological responses and are considered good bio-indicators of stress and potential indicators of ecosystem health. Bivalves are currently used in ecotoxicological bioassays because of their ecological importance, wide geographic distribution, ease of handling in the laboratory and in the field, and their ability to filter and ingest large volumes of water and sediment particles. Thus, the main goal of this work was to determine the toxic and biochemical (namely fatty acid profiles) responses of two size classes (small and big) of the two marine bivalve species Cerastoderma edule and Scrobicularia plana to the herbicide Primextra ® Gold. Furthermore, we aimed to compare the fatty acid contents, and thus the nutritive values, of both species and size classes collected in the field with those under laboratory conditions. Results show S. plana is more sensitive to the herbicide than C. edule. In general, among the larger-sized specimens in the field, S. plana is more nutritive than C. edule, but among the smaller-sized specimens, the opposite tendency is seen, where C. edule presents a greater abundance of FAs. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction In Europe, mainly in the Mediterranean region, there is an overexploitation of farmland, and when combined with fertil- izer and pesticide overuse, has adverse effects on surrounding aquatic systems. Because many estuaries are surrounded by farm- land, residential, and industrial areas, they are subject to various ∗ Corresponding author at: IMAR (Marine and Environmental Research Centre) & MARE (Marine and Environmental Sciences Centre), Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal/Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal. Tel.: +351 239855760; fax: +351 239823603. E-mail address: anamartagoncalves@ua.pt (A.M.M. Gonc ¸ alves). anthropogenic pressures and behaviors that cause ecological stresses, affecting not only the water quality, but also the biological communities of these ecosystems (McCarthy et al., 2007; Cardoso et al., 2008; Gonc ¸ alves et al., 2010a, 2010b; Sameling et al., 2013; Verdelhos et al., 2005, 2014). As in other estuaries, Mondego estuary, located near Figueira da Foz city, Portugal, is under strong anthropogenic pressures. The main stressors are related to port, beach, and industrial activities as well as the exploitation of marine resources. The eutrophica- tion process is caused primarily by discharges of pollutants (e.g., fertilizers and inorganic compounds) from agricultural fields, par- ticularly those used to grow rice and corn, where production is more intensive (Cardoso et al., 2008; Duarte et al., 2008). Pes- ticides used in agricultural practices have been found in surface http://dx.doi.org/10.1016/j.ecolind.2015.12.006 1470-160X/© 2015 Elsevier Ltd. All rights reserved.