Chemical pollution of aquatic ecosystems represents an ecological threat that has been receiving increased attention. Bioindicator species are organisms used to monitor the status or quality of ecosystems, providing quantitative data for the presence of pollutants. Bioindicators from different trophic levels, such as algae, bivalve molluscs or fish species, are commonly used to evaluate the chemical contamination at different stages of the food webs. In general, carnivorous fish occupy the highest ranks of aquatic food webs and tend to accumulate larger amounts of persistent contaminants in their tissues(Mansour and Sidky, 2002), while bivalve molluscs (e.g.mussels, clams and oysters)are sedentary and filter-feeding organisms that can concentrate contaminants from the sediment, suspended particulate material and water column(Laffon etal.,2006). Aquatic algae are also considered as important producers in marine waters, playing a key role in the whole marine ecosystem and directly reflecting the water quality(Zhou etal.,2008; Hamza-Chaffai, 2014). Brown kelp species, such as Laminaria digitata, have shown to have high accumulation rates and affinity for a wide range of elements, thus being interesting bioindicators of toxic metal pollution(Davis et al.,2003). Thus, given the specific characteristics of each species and depending on the target contaminant, an appropriate selection of the sentinel species is a crucial step in environmental monitoring.