Impact of kelp cultivation on the Ecological Status of benthic habitats and Zostera marina seagrass biomass

The Ecological Status of subtidal benthic communities within a commercial kelp farm on the southwest coast of Ireland was not impacted by macroalgal cultivation. Additionally, there was no effect on the biomass of Zostera marina, a key habitat under the EU Habitats Directive and OSPAR Commission. However, sediment grain size and total organic matter (TOM) were influenced by abiotic and biotic aspects of the farm. A temporal effect on univariate and multivariate species data, Infaunal Quality Index (IQI) and Z. marina biomass was observed. This effect was likely a community response to high storm disturbance in winter 2013/14. The use of IQI to assess the impact of macroalgal cultivation on benthic communities is a novel approach. This study supports a view that environmental impacts of macroalgal cultivation are relatively benign compared to other forms of aquaculture. Further research must be conducted to understand all interactions between aqua culture activities and the environment.