Impact of deep-water fish farms on benthic macrofauna communities under different hydrodynamic conditions

• Published in: Marine pollution bulletin Vol. 101; no. 2; pp. 776 - 783
• Main Authors: Valdemarsen, Thomas, Hansen, Pia Kupka, Ervik, Arne, Bannister, Raymond J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 30.12.2015
• Subjects: Animals; Aquaculture; Aquaculture - methods; Aquatic Organisms; Biodiversity; Bioirrigation; Bioturbation; Capitella capitata; Diversity; Ecosystem functioning; Environment; Environmental Monitoring; Fishes; Hydrodynamics; Marine; Norway; Vigtorniella ardabilia; Water Pollutants, Chemical - analysis; Norway; Bioturbation; Capitella capitata; Vigtorniella ardabilia; Diversity; Ecosystem functioning; Bioirrigation; Aquaculture
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2015.09.036

In this study the environmental impacts of two fish farms located over deep water (180–190m) were compared. MC-Farm was located at a site with slightly higher water currents (mean current speed 3–5cms−1) than LC-farm (<2cms−1). Macrofauna composition, bioirrigation and benthic fluxes (CO2 and NH4+) were quantified at different stages of the production cycle, revealing very different impact of the two farms. Macrofauna abundance and bioirrigation were stimulated compared to a non-impacted reference site at MC-farm, while macrofauna diversity was only moderately reduced. In contrast, macrofauna communities and related parameters were severely impoverished at LC-Farm. This study suggests that deep-water fish farms should not be sited in low current areas (<2cms−1), since this will hamper waste dispersal and aggravate environmental impacts. On the other hand, fish farming at slightly more dynamic sites can lead to stimulated benthic macrofauna communities and only moderate environmental impacts. •The environmental impacts of two similar deep-water fish farms were compared.•The hydrodynamic conditions differed slightly under the two farms.•At one farm (low flow) benthic macrofauna and biogeochemical functioning were impaired.•At the other farm (moderate flow) benthic impacts were detectable but not critical.•Environmental impacts of deep-water fish farms are highly dependent on hydrodynamics.