Effects of shellfish farming on the benthic environment

• Published in: Aquaculture Vol. 224; no. 1; pp. 117 - 140
• Main Authors: Crawford, Christine M, Macleod, Catriona K.A, Mitchell, Iona M
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30-06-2003; Elsevier Science; Elsevier Sequoia S.A
• Subjects: Algae; Animal aquaculture; Animal productions; Aquaculture; Benthic environment; Biological and medical sciences; Environmental impact; Fundamental and applied biological sciences. Psychology; Invertebrata; Invertebrate aquaculture; Marine; Others; redox potential; Salmonidae; Shellfish; Shellfish farming; Australia; Tasmania; Oceania; Tasmania Australia; Australia, Tasmania; PSE, Australia, Tasmania; Benthic environment; Environmental impact; Shellfish farming; Marine environment; Organic carbon; Shellfish; Environment impact; Turbidity; Environmental factor; Sediments; Aquaculture; Benthic zone
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/S0044-8486(03)00210-2

The benthic environment under and near three shellfish farms in Tasmania, Australia, which had had a relatively high level of production over many years was investigated. Benthic samples were collected along transects which ran across the farms, generally from 100 m upstream to 100 m downstream. Sediment deposition, redox values, sediment sulphide concentrations, organic carbon content and water turbidity levels near the bottom were significantly different between the farms but not between sites outside the farm, at the boundary and sites within the farm. Video recordings at one farm showed dense coverage of fine filamentous algae and patchy bacterial mats directly under some longlines and this algae is thought to have fallen off the mussel longlines. At another farm dense beds of seagrass were observed in the videos both under trays of oysters and outside the farm. The benthic infauna did not show clear signs of organic enrichment, and neither univariate nor multivariate measures of benthic infauna were significantly different between sites inside and outside the farm, although they were different between farms.
It was concluded from these results that shellfish farming is having little impact, and much less than salmon farming, on the benthic environment in Tasmania. Thus extensive monitoring of shellfish farms would appear to be not necessary.