Assessing the suitability of a range of benthic indices in the evaluation of environmental impact of fin and shellfish aquaculture located in sites across Europe. Borja, Á., Rodríguez, J.G., Black, K., Bodoy, A., Emblow, C., Fernandes, T.F., Forte, J., Karakassis, I., Muxika, I., Nickell, T.D., Papageorgiou, N., Pranovi, F., Sevastou, K., Tomassetti, P. & Angel, D., 2009. Aquaculture 293(3-4): 231-240.
The Ecosystem Approach for Sustainable Aquaculture (ECASA) project, an EU Framework 6 funded programme investigated the applicability of quantitative indicators of environmental impact from aquaculture sites as far ranging as Abornes in arctic Norway to Sounion in Greece. At 6 Mediterranean and 4 Atlantic aquaculture sites, and including a variety of cultured species (seabream, seabass, tuna, salmon, cod, oysters, mussels, and clams), sampling was carried out along gradients of enrichment, obtaining sediment, hydrodynamic, and benthic faunal data.
Across these European sites, the horizontal impact from organic enrichment extended 50 m from the farms; several indicators of benthic impact were contradictory (individual macrofaunal abundance and biomass), while the Infaunal Trophic Index (ITI) and AZTI's Marine Biotic Index (AMBI) were much more consistent indicators. Three main physical factors explained the majority of farm impacts: 1) hydrography (depth, distance to farm, average current speed; 2) sediment (redox potential and percentages of silt and total organic matter); and 3) intensity of production (years of production and annual production).
The authors conclude that assessing the response of benthic communities to organic enrichment from aquaculture may be improved by using a suite of benthic indicators (rather than a single indicator), and considering all of the physical variables above, with implications for designing monitoring programmes of aquaculture impacts and site selection.
For more information on the ECASA project visit the ECASA Toolbox website