Rationale 2.5

The benthic zone (‘bottom’) of a waterbody often supports a rich biodiversity and provides critical ecological functions such as assimilation of organic waste (e.g. faeces, uneaten feed), provision of food for species and protection of coastal sediment from erosion. Human activities interacting with the benthic zone can negatively impact the functioning of these ecosystems.

Aquaculture can interact with the benthic zone through deposition of organic waste and release of heavy metals.3131González-Gaya, B., García-Bueno, N., Buelow, E., Marin, A., & Rico, A. (2022). Effects of aquaculture waste feeds and antibiotics on marine benthic ecosystems in the Mediterranean Sea. Science of the Total Environment, 806, 151190. When this deposition exceeds the environment’s ability to handle it, harmful changes to the ecosystem can occur. 3232Hargrave, B. T., Phillips, G. A., Doucette, L. I., White, M. J., Milligan, T. G., Wildish, D. J., & Cranston, R. E. (1997). Assessing benthic impacts of organic enrichment from marine aquaculture. In The Interactions Between Sediments and Water: Proceedings of the 7th International Symposium, Baveno, Italy 22–25 September 1996 (pp. 641-650). Springer Netherlands.The severity of these impacts depends on factors such as the amount of waste released, waterbody characteristics and the ability of the benthic microbial community to break down waste.3333Kalantzi, I., & Karakassis, I. (2006). Benthic impacts of fish farming: meta-analysis of community and geochemical data. Marine Pollution Bulletin, 52(5), 484-493.

This Criterion focuses on effective management by ASC-certified farms to monitor the local benthic zone and limit these impacts by ensuring waste deposition is lower than the natural decomposition rate.

Intent – The aquaculture industry maintains healthy benthic ecosystems.