MEPS 267:99-105 (2004)  -  doi:10.3354/meps267099

Acoustic detection of organic enrichment in sediments at a salmon farm is confirmed by independent groundtruthing methods

D. J. Wildish1,*, J. E. Hughes-Clarke2, G. W. Pohle3, B. T. Hargrave4, L. M. Mayer5

1Biological Station, Fisheries & Oceans Canada, 531 Brandy Cove Road, St. Andrews, New Brunswick E5B 2L9, Canada
2Department of Geodesy & Geomatics Engineering, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick E3B 5A3, Canada
3Huntsman Marine Science Centre, 1 Lower Campus Road, St. Andrews, New Brunswick E5B 2L7, Canada
4Bedford Institute of Oceanography, Fisheries & Oceans Canada, Dartmouth, Nova Scotia B2Y 4A2, Canada
5Darling Marine Center, University of Maine, 193 Clarks Cove Road, Walpole, Maine 04573, USA

ABSTRACT: Acoustic backscatter contrast in depositional sediments under salmon farm cages in the Bay of Fundy, Canada, was correlated with localized changes in (unknown) sediment geotechnical properties, as indicated by 4 independent measures of organic enrichment. Sediment total sulfides and redox potentials, enzyme hydrolyzable amino acids, sediment profile imaging and macrofaunal samples, taken at mid-cage positions, each rejected the null hypothesis that salmon cage footprints, defined acoustically as high backscatter areas, were indistinguishable from nearby reference areas. Acoustic backscatter imaging appears capable of mapping organic enrichment in depositional sediments caused by excessive inputs of salmon farm wastes associated with intensive aquaculture.


KEY WORDS: Organic enrichment · Multi-beam acoustics · Sedimentary sulfides · Sediment profile imaging · Aquaculture


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