Differences in the trophic ecology of several littoral fish species along thermal gradients at the Western European shoreline were investigated as part of the EU/BMBF funded ERANET project MarinERA Marine phylogeographic structuring during climate change: the signature of leading and rear edge of range shifting populations. The aim was to assess the impact of climate change on the adaptability and changes in the feeding behaviour of specific littoral fish populations at their northern and southern distribution limits (cold- and warm-adapted species). During a first sampling campaign in 2009 the target fish species Pomatoschistus minutus, Ctenolabrus rupestris and Symphodus melops as well as herbivores (Littorina littorea and Mytilus edulis) from different populations were sampled along a gradient from 36°N to 58°N thus experiencing different thermal conditions. Fatty acid profiles and stable isotope signatures (δ13C, δ15N) as indicators for the trophic ecology of target fish species and herbivores were analysed and variations along latitudinal gradients assessed. Furthermore, issues such as the degree of trophic overlap between target fish species, their niche widths and their adaptive potential will be addressed in the light of ongoing climate change.