Characterization of the suspended organic particles released from salmon farms and their potential as a food supply for the suspension feeder, Mytilus edulis in integrated multi-trophic aquaculture (IMTA) systems

The successful utilization of aquaculture-generated organic particles as a food source for marine bivalves cultured in an integrated multi-trophic aquaculture (IMTA) system depends both on the occurrence of sufficient particles within the edible size range for the species, and determining the distribution and rate of particle dispersal around the farms. In this study we characterize the distribution of organic particulate enrichment at and around Atlantic salmon (Salmo salar) aquaculture farms in the Bay of Fundy to assess its availability to the blue mussel (Mytilus edulis) on spatial and temporal scales. Long-term temporal cycles indicate overall increases in particulate organic matter (POM) at aquaculture cage locations compared to reference locations independent of time of year. Spatially, POM levels increase 2 to 4 times over ambient levels adjacent to cages, but drop to ambient levels after distances of 10 m from the cage. Daily POM levels are higher at salmon farm cages than reference locations and often correlate strongly with daily fish feeding regimes. The majority of particles from the aquaculture cages are small (1-10 μm), within the utilizable size range for the blue mussel and of very high quality (up to 90% organic content). Pulses of organic enrichment from salmon aquaculture farms are a dependable and bioavailable food source for the blue mussel when grown directly within the particle plume generated from the farm.