“…In each region, one site affected by intense anthropogenic activity (polluted) was chosen, as well as one secluded (clean) site. The three referenced contaminated sampling sites, port of Vigo, 42.228753N, 8.761500W (polluted 1, P1), port of Viana do Castelo, 41.679828N, 8.836414W (polluted 2, P2) and port of Leixões, in Matosinhos, 41.183427N, 8.698586W (polluted 3, P3), are all located in urban centres, very close to intense port activity, being thus affected by different sources of contamination from fuels, oil spills, vessels' coating materials, etc (Bellas et al, 2011;Besada et al, 2011aBesada et al, , 2011bLima et al, 2007;Cairrão et al, 2004;Cunha et al, 2005) (Fig. 1).…”