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)

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.