Active coral propagation outcomes on coral communities at high-value Great Barrier Reef tourism sites

Abstract

Tourism-led stewardship of Great Barrier Reef (GBR) sites has implemented upscaling of coral propagation and out-planting practices. Incorporating ecological monitoring into restoration practices has long been acknowledged as a vital component of reef restoration projects – thereby demonstrating success in relation to improved ecosystem function within impacted reefs. As such, one goal for this tourism-led stewardship project was to identify whether and how activity increased coral cover and target species populations within high-value tourism sites. We therefore investigated coral cover and relative cover of commonly out-planted genera within seven tourism sites over six reefs on the northern GBR via benthic surveys, both prior to the commencement of out-planting activities in August 2019, and again in August 2021. Over this 24-month time frame, out-planting intensity varied between 3970 and 84 out-plants within marked areas (with no propagation activity conducted within corresponding control areas) across sites. Within all out-planting sites, > 65 % of out-plants were Acropora species. One reef showed a significant increase in hard coral cover – 10.3 % (p = 0.016) – at out-planting areas compared to control areas by August 2021. At this same reef, proportions of total coral cover attributed to Acropora species were higher within the out-planting site compared to the control site. Despite variability in coral community responses observed across reef site/operators, we have demonstrated how coral propagation via this tourism-led stewardship model has the potential to increase hard coral cover within some out-planting sites, particularly of commonly out-planted genera.