Nutrient extraction and ecosystem impact by suspended mussel mitigation cultures at two contrasting sites

• Published in: The Science of the total environment 2023-08, Vol.888, p.164168-164168, Article 164168
• Main Authors: Maar, Marie, Larsen, Janus, Schourup-Kristensen, Vibe, Taylor, Daniel
• Format: Article
• Language: English
• Subjects: Biogeochemical cycles; Coastal waters; Ecosystem model; Eutrophication; Low-trophic aquaculture; Marine ecology
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.164168

Mussel mitigation culture is increasingly recognized as a tool to extract nutrients from eutrophic systems by harvesting mussel biomass and nutrients contained therein. The net effect of mussel production on the nutrient cycling in the ecosystem is, however, not straightforward due to the interaction with physical- and biogeochemical processes regulating ecosystem functioning. The aim of the present study was to evaluate the potential of using mussel culture as a tool to mitigate eutrophication at two contrasting sites: a semi-enclosed fjord and a coastal bay. We applied a 3D coupled hydrodynamic-biogeochemical-sediment model combined with a mussel eco-physiological model. The model was validated against monitoring data and research field data on mussel growth, sediment impacts, and particle depletion from a pilot mussel farm in the study area. Model scenarios with intensified mussel farming in the fjord and/or the bay were conducted. The results showed that mussel mitigation culture still has a high net N-extraction when including ecosystem effects, such as changes in biodeposition, nutrient retention, denitrification, and sediment nutrient fluxes in the model. Mussel farms located in the fjord were more effective in directly addressing excess nutrients and improving water quality due to the relative vicinity to primary nutrient sources (riparian) and physical characteristics of the fjord system. The results will be important to consider in other systems concerning site selection, development of bivalve aquaculture, and associated sampling strategies for monitoring the farming impacts. [Display omitted] •The net effect of bivalve culture on ecosystem nutrient cycling is uncertain.•3D high-resolution ecosystem-mussel farm modeling was applied at two contrasting sites.•Water quality showed higher improvement in a restricted fjord than in an exposed bay.•Mussel mitigation culture showed a high net extraction of nitrogen at ecosystem scale.•Important for further development, site selection, and monitoring of mussel culture.