Macroalgal removal on the reefs of Magnetic Island


Reef Ecologic Adam Smith with some freshly removed macro algae

Macroalgal removal has been proposed as an active intervention measure to aid reef recovery, through reduced competition and increased benthic substrate for coral recruitment. The baseline information on the effects (both positive and negative) of macroalgal removal on reef community structure and ecology have not been rigorously tested however despite pilot projects on the Great Barrier Reef and elsewhere. This project aims to quantify the ecological effects of macroalgal removal on reefs surrounding Magnetic Island. The effects of macroalgal removal on corals will be evaluated, by assessing quantifying benthic taxa abundance and community diversity, fish assemblages, coral recruitment levels and the photobiology of coral colonies in permanent replicate quadrats with and without active algal removal.

Coral recruitment tile set in a cleared plot

The team led by Honours’ student Elissa Mastroianni cleared macroalgae from six quadrats between Arthur and Florence Bay prior to coral spawning last November. Results from this study will help determine the viability of macroalgal removal as an intervention strategy to promote coral recovery on the reefs of Magnetic island. Other intervention measures such as coral transplantation or larval enhancement may be considered to complement the algae removal efforts in the future.

The project is supervised by Associate Professor David Bourne, Dr Lisa Boström-Einarsson, and Professor Peter Harrison, in partnership with GBRMPA and Reef Ecologic.

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Associate professor David Bourne



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