Researchers investigating the environmental impacts of fish farm effluents on freshwater streams have found that feed-pellet-derived materials significantly contribute to the benthic food chain.

In their study, the group from France examined how aquaculture effluent from rainbow trout (Oncorhynchus mykiss) farms affects aquatic organisms in three different streams with varying discharge rates.

According to the authors, “feed pellets from each farm were significantly 13C-enriched compared to the isotopic backgrounds of the receiving streams. Benthic invertebrates and small-bodied fish were consistently 13C-enriched downstream the fish farm effluents.”

Comparisons found high amounts of pellet-derived materials in the diets of these organisms, indicating that trout farm effluent enhanced the detritus-based food chain.

This article includes excerpts from the study abstract, published in the Journal of Aquaculture