Impact of fish farm deposition on maerl beds.

Abstract

There is an ongoing search for marine fish farming sites that have the minimum environmental impact yet create quality produce and economic benefits. In the north and west of Scotland, candidate areas sometimes include maerl beds as these calcareous algal deposits tend to occur in areas sheltered from wave action with strong tidal water movement that may reduce the build-up of organic matter. Maerl beds are a UK Biodiversity Action Plan habitat and this report is the culmination of collaborative research between Scottish Natural Heritage (SNH), the Scottish Environment Protection Agency (SEPA) and Marine Harvest (Scotland) (MHS). Previously, it was unknown whether maerl beds would be resilient to fish farm operation, by virtue of the strong tidal flows that typify maerl grounds, or whether these habitats were easily degraded. Experimental evidence from laboratory studies has, however, shown that maerl is particularly sensitive to siltation and lowered oxygen levels (Wilson et al., 2004). This study was undertaken to investigate the effects of fish farm deposition on maerl beds.