Action: Locate artificial reefs near aquaculture systems to benefit from nutrient run-offs
Key messagesRead our guidance on Key messages before continuing
- Two studies examined the effects of locating artificial reefs near aquaculture systems to benefit from nutrient run-offs on subtidal benthic invertebrate populations. One study was in the Gulf of Aqaba (Israel and Jordan), and one in the Mediterranean Sea (Spain).
COMMUNITY RESPONSE (1 STUDY)
- Overall community composition (1 study): One controlled study in the Mediterranean Sea found that an artificial reef located under aquaculture cages had similar invertebrate community composition to artificial reefs located at sites without aquaculture cages.
POPULATION RESPONSE (1 STUDY)
- Overall abundance (1 study): One controlled study in the Gulf of Aqaba found that an artificial reef located at an aquaculture site had similar invertebrate biomass growing on it compared to an artificial reef located at a site without aquaculture cages.
Artificial reefs are man-made structures intentionally put into the marine environment to act similarly to a natural reef. Originally used to improve fisheries and biological resources, they have been shown to be ecologically beneficial by locally enhancing biodiversity and increasing abundance (Bohnsack & Sutherland 1985; Clark & Edwards 1999). By locating an artificial reef near an aquaculture system, the introduced reef can potentially benefit from the nutrient-rich run-offs frequently associated with aquaculture systems, thereby promoting the colonisation and development of a subtidal benthic invertebrate community on the reef (Aguado-Giménez et al. 2011).
Evidence for related interventions is summarised under “Threat: Pollution – Locate artificial reefs near aquaculture systems to act as biofilters” and “Threat: Energy production and mining – Co-locate aquaculture systems with other activities and infrastructures (such as windfarms)”.
Aguado-Giménez F., Piedecausa M.A., Carrasco C., Gutiérrez J.M., Aliaga V. & García-García B. (2011) Do benthic biofilters contribute to sustainability and restoration of the benthic environment impacted by offshore cage finfish aquaculture? Marine Pollution Bulletin, 62, 1714–1724.
Bohnsack J.A. & Sutherland D.L. (1985) Artificial reef research: a review with recommendations for future priorities. Bulletin of Marine Science, 37, 11–39.
Clark S. & Edwards A.J. (1999) An evaluation of artificial reef structures as tools for marine habitat rehabilitation in the Maldives. Aquatic Conservation: Marine and Freshwater Ecosystems, 9, 5–21.
Supporting evidence from individual studies
A controlled study in 1999–2000 of two artificial reefs in an area of sand and seagrass in the Gulf of Aqaba (Gulf of Eilat), Red Sea, Israel and Jordan (Angel et al. 2002) found that, after one year, an artificial reef deployed at an aquaculture site did not appear to develop a higher biomass of sessile invertebrates compared to an artificial reef deployed at a site without aquaculture activity. Data were not statistically tested. Biomass of invertebrates varied between the two reefs following deployment and tended to be similar after a year (approximately 700 kg/reef). In March 1999, two artificial reefs (8.2 m3) were deployed at 20 m depth: one at a fish farm, and another at a site 500 m west of the fish farm without aquaculture activity. Each reef held multiple 30 × 45 cm sample plates used for invertebrates to colonise. Three plates were sampled monthly from each artificial reef, photographed, dried, and the biomass of attached invertebrates recorded.
A controlled study in 2006–2007 of three sites in one soft seabed area off the coast of Murcia, Mediterranean Sea, southeastern Spain (Aguado-Giménez et al. 2011) found that, after one year, an artificial reef deployed underneath aquaculture cages did not develop a more diverse invertebrate community compared to artificial reefs deployed at sites without aquaculture cages. Invertebrate community composition varied during the year following deployment, but the artificial reef located under the cages had similar invertebrate community composition to those located away from the cages at each sampling time (data presented as statistical model results). In May 2006, three biofilter-like artificial reefs were deployed at 37–38 m depths: one underneath aquaculture cages, and two at sites without cages located 1.3 and 1 km away from the aquaculture site respectively. Each reef held multiple 30 × 30 cm sample units. Four randomly-chosen units were sampled by divers in summer and autumn 2006, winter 2006/07, and spring and summer 2007, at each reef. Invertebrates growing on the structures were identified and counted for each unit.
- Angel D.L., Eden N., Yuman A., Katz T. & Spanier E. (2002) In situ biofiltration: a means to limit the dispersal of effluents from marine finfish cage aquaculture. Hydrobiologia, 469, 1-10
- Aguado-Giménez F., Piedecausa M.A., Carrasco C., Gutiérrez J.M., Aliaga V. & García-García B. (2011) Do benthic biofilters contribute to sustainability and restoration of the benthic environment impacted by offshore cage finfish aquaculture? Marine Pollution Bulletin, 62, 1714-1724