From soil to sea: An ecological modelling framework for sustainable aquaculture

An integrated framework is presented for carrying capacity assessment of aquaculture. The SUCCESS (System for Understanding Carrying Capacity, Ecological, and Social Sustainability) modelling framework uses a catchment to coast approach and is therefore able to partition organic and inorganic loading from disparate sources, resolve primary production, and simulate aquaculture carrying capacity. An application of this framework to bivalve shellfish culture in Dundrum Bay, Northern Ireland, is used to illustrate: (i) how High-Impact-Short-Term (HIST) events such as pulse discharges from sewer systems can play an important role in changing environmental conditions in the receiving water; (ii) how changes in land-based loads can affect bay-scale nutrient enrichment and shellfish yields; and (iii) the role bivalves such as oysters and mussels can play in top-down control of eutrophication symptoms. Our results show that in Dundrum Bay bottom-up control due to reduction of land-based loads can result in a 40% reduction in shellfish harvest, and that top-down control of phytoplankton and organic detritus by cultivated filter-feeders can reduce the percentile 90 of chlorophyll (i.e. the typical maximum) by over 20%. Both these results have important consequences for water quality and human use, and illustrate the complexity of integrated coastal management in multi-use systems. The capacity of SUCCESS to analyse source apportionment from land, interactions at the open ocean interface, aquaculture production and environmental effects, and key biogeochemical processes at the bay scale, as a digital twin of the soil-to-sea continuum, makes it an important toolset for policy makers tasked with managing complex coastal systems.