To determine the contribution of the faecal pellets produced by fouling fauna to the organic matter pool of an Offshore Wind Farm, it is fundamental to distinguish between the different contributors to this organic matter pool. For this reason, my current work focuses on looking for a specific-species tracer that can be used distinctive marker, like a fingerprint. I do this by looking at the ¹³N isotopic signal of the amino acids present in the faecal pellets produced by the species subject of this study; Mytilus edulis, Metridium senile, and Jassa herdmani.