Abstract:
On inshore coral reefs, coral cover declines from disturbances are often accompanied by increases in macroalgal cover. Thus, coral recovery often occurs against a backdrop of elevated macroalgae cover. While ‘macroalgae’ are generally assumed to reduce coral recruitment, their taxonomic composition and structure vary considerably. Here, we test whether different macroalgal assemblages affect coral recruitment on an inshore reef by experimentally manipulating macroalgal assemblages within forty 1 m 2 plots on the shallow reef crest in Florence Bay, Magnetic Island (central inshore Great Barrier Reef). Specifically, we investigated the effect of canopy-forming macroalgae (e.g. Sargassum, Turbinaria, Sirophysalis), understorey macroalgae (e.g. Hypnea, Lobophora, Padina), mixed macroalgal assemblages (both canopy- and understorey macroalgae) and plots cleared of macroalgae on rates of coral recruitment to tiles. We also quantified coral size frequency distribution in Florence Bay to investigate its relationship with macroalgal structure and composition. The presence of canopy-forming macroalgae was the most important factor affecting coral recruitment, with coral recruitment being ~ fivefold greater in plots with no canopy-forming macroalgae compared to those with canopy-forming macroalgae. Moreover, the presence of two macroalgal taxa, Sargassum and Lobophora,
