Explaining the distribution and abundance patterns of organisms in the natural environment is a central objective of ecological theory. Predation and competition have long been seen as major drivers of diversity and abundance, while more recently ‘supply-side’ ecology has developed as a potentially important factor explaining populations dynamics. Marine sessile and sedentary species comprise a large component of rocky shoreline biodiversity. For many benthic organisms, broadcast spawning is the primary mode of reproduction with extremely high larval output potentially making larval supply a key step in their ecology. Large-scale studies (over 100’s of km’s) of supply-side ecology are uncommon. Aquaculture, however, provides a perfect opportunity to conduct large-scale ‘supply-side’ research by substantially increasing source populations and the opportunity for increased larval supply. The smoothshelled mussel Mytilus galloprovincialis is farmed in two open coastal embaymen