Fate and longevity of terrestrial fatty acids from caged fin-fish aquaculture in dynamic coastal marine systems

Abstract

Fin-fish production continues to expand with the switch in diet from traditional fish meals and oils to terrestrial sourced components. Terrestrial crops can be traced into the marine environment due to their high abundance of C18 fatty acids (FA). Here we compare two FA extraction techniques on coastal sediments; Folch lipid extraction and direct methylation. We found differences in the FA classes which could be extracted using these methods, and that direct methylation extracted more of the terrestrial biomarkers. We applied the direct methylation method to detect organic waste dispersal from a fin-fish farm along a transect in sedimentation and sediment samples across a production cycle, along with polychaetes collected during post-peak production. We traced organic waste from the fin-fish farm as far as 1100 m by mid production. Furthermore, we found polychaetes to have FA profiles reflective of the sediment, indicating they are assimilating aquaculture waste.