Assessment of Finfish Aquaculture Effect on Newfoundland Epibenthic Communities through Video Monitoring

• Published in: North American journal of aquaculture 2015-04, Vol.77 (2), p.117-127
• Main Authors: Hamoutene, Dounia, Salvo, Flora, Bungay, Terrence, Mabrouk, Gehan, Couturier, Cyr, Ratsimandresy, Andry, Dufour, Suzanne C.
• Format: Article
• Language: English
• Subjects: Beggiatoa
• ISSN: 1522-2055; 1548-8454
• DOI: 10.1080/15222055.2014.976681

In Newfoundland fjords, evaluating changes to benthic communities resulting from finfish aquaculture is difficult because the depth (>30 m) and presence of patches of hard substrates at production sites hinder grab sampling. In this study, we used video surveys to characterize benthic assemblages at sites with no aquaculture, with varying amounts of finfish production, and undergoing fallowing periods. Video analyses revealed a patchy distribution of benthic organisms (identifiable at a high taxonomic level), characterized by low natural abundances and richness. Benthic communities at aquaculture sites showed evidence of organic matter enrichment through the presence of Beggiatoa sp. or opportunistic polychaete‐dominated assemblages (or both), bare stations, flocculent matter, and lower abundances and richness near aquaculture cages. Maps of sites in production showed that the area of aquaculture impact was influenced by bathymetry, located underneath cages and in some instances up to 145 m away from net‐pens, and often directed away from the coastline. However, correlations of abundances and richness with distance from cage were weak, and stations close to cages were not always statistically different from stations further away or at the nonproduction site. At the fallow site, a large percentage (∼70%) of stations was barren, suggesting potentially hypoxic or anoxic conditions and warranting further investigations of fallow periods. Our analysis confirms that video‐based assessments can detect major aquaculture‐related changes in benthic communities but cannot, at present, identify lower levels of disturbance.