AEI 9:127-143 (2017)  -  DOI:

Vertical particle fluxes dominate integrated multi‑trophic aquaculture (IMTA) sites: implications for shellfish-finfish synergy

R. Filgueira1,*, T. Guyondet2, G. K. Reid3,4, J. Grant5, P. J. Cranford

1Marine Affairs Program, Dalhousie University, 1355 Oxford St., PO Box 15000, Halifax, NS B3H 1R2, Canada
2Department of Fisheries and Oceans, Gulf Fisheries Centre, Science Branch, PO Box 5030, Moncton, NB E1C 9B6, Canada
3Canadian Integrated Multi-Trophic Aquaculture Network (CIMTAN), University of New Brunswick, PO Box 5050, Saint John, NB E2L 4L5, Canada
4Department of Fisheries and Oceans, St. Andrews Biological Station, 531 Brandy Cove Rd., St. Andrews, NB E5B 2L9, Canada
5Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
6Department of Fisheries and Oceans, Bedford Institute of Oceanography, 1 Challenger Dr., Dartmouth, NS B2Y 4A2, Canada
*Corresponding author:

ABSTRACT: Maximizing the mitigation potential of open-water finfish-shellfish integrated multi-trophic aquaculture (IMTA) farms is complex in terms of co-locating the trophic components. Both the dispersal of finfish aquaculture wastes and biological processes are highly influenced by water circulation. Consequently, the evaluation of shellfish-finfish synergy requires a combined study of biological and physical processes, which can be achieved by the implementation and coupling of mathematical models. A highly configurable mathematical model was developed that can be applied at the apparent spatial scale of IMTA sites. The model tracks different components of the seston, including feed wastes, fish faeces, shellfish faeces, natural detritus and phytoplankton. Based on the characterization of these fluxes, a hypothetical IMTA site was used to explore different spatial arrangements for evaluating finfish-shellfish farm mitigation efficiency. The site was modelled following a factorial design, which tested 2 levels of background seston concentrations, 3 farm designs, 2 hydrodynamic conditions and 2 levels of aquaculture intensity. The model predicts that mitigation efficiency is highly dependent on the background environmental conditions, obtaining maximum mitigation under oligotrophic conditions that stimulate shellfish filtration activity. The dominance of vertical fluxes of particulate matter triggered by the high settling velocity of finfish aquaculture wastes suggests that suspended shellfish aquaculture cannot significantly reduce organic loading of the seabed. Consequently, this suggests that waste mitigation at IMTA sites should be best achieved by placing organic extractive species (e.g. deposit feeders) on the seabed directly beneath finfish cages rather than in suspension in the water column.

KEY WORDS: Settling velocity · Organic loading · Mitigation · Connectivity · Ecosystem model

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Cite this article as: Filgueira R, Guyondet T, Reid GK, Grant J, Cranford PJ (2017) Vertical particle fluxes dominate integrated multi‑trophic aquaculture (IMTA) sites: implications for shellfish-finfish synergy. Aquacult Environ Interact 9:127-143.

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