Assessing novel cultivation methods, baseline fish assemblages and survey methodologies of cultivated and wild kelp in the Southwest of Ireland

Abstract

Kelp (i.e. large brown macroalgae of the order Laminariales) are important habitat-forming species in coastal ecosystems. Recently, the key role kelp play as part of an expanding blue economy has been recognised in addition to their use as a mitigation tool for climate-driven impacts and other threats posed by anthropogenic activities. Unfortunately, kelp beds and forests globally are under increasing threat due to anthropogenic activities. Paradoxically, kelp has been identified as a mitigation tool for multiple anthropogenically induced environmental impacts. It has arguably never been more urgent to address key knowledge gaps to understand the role kelp play in coastal ecosystem functioning. This study aimed to: (i) address current knowledge gaps surrounding the link between diversity and productivity in relation to biomass production in algal aquaculture (Chapter 2); (ii) describe the fish communities associated with wild kelp beds in SW Ireland (Chapter 3); and (iii) test methods of quantifying fish assemblages associated with kelp farms (Chapter 4). The interaction between juvenile sporophytes of three native Irish kelp species were found to be selective, with a single species dominating in mixed assemblages. The fish communities associated with Laminaria hyperborea were mainly composed of species of the families Gobiidae, Gadidaea and Labridae. Underwater visual census surveys via scuba were identified as an appropriate method for quantifying fish communities at kelp cultivation structures.