Coral –algae competition: Patterns, mechanisms and responses to ocean acidification

Coral – algal dynamics in response to the 2006 warming-induced coral bleaching event. Data from the reef slopes of four islands in the Keppel Islands, southern Great Barrier Reef. % cover data are means (n = 10) 6SE, except for Feb 2006 (n = 25–26). CCA: Crustose calcareous algae. doi:10.1371/journal.pone.0005239.g002

Coral – algal dynamics in response to the 2006 warming-induced coral bleaching event. Data from the reef slopes of four islands in the Keppel Islands, southern Great Barrier Reef. % cover data are means (n = 10) 6SE, except for Feb 2006 (n = 25–26). CCA: Crustose calcareous algae. doi:10.1371/journal.pone.0005239.g002

Macroalgae and corals are the dominant benthic groups in coral reefs and compete intensively for the available space. For example, following coral disturbances such as coral bleaching and cyclones, macroalgae are released from space competition with corals and colonise the newly available space. Despite the importance of competition to community structure and reef resilience, very little is known about the natural history of coral-algal interactions in the Great Barrier Reef. To fill in this gap, we are currently quantifying the natural occurrence and types of coral-algal interactions in a range of reefs in the GBR and Moreton Bay, QLD.

 

As the concentrations of CO2 increase in seawater as a consequence of accelerated emissions of CO2 to the atmosphere by human activities, and given that CO2 is a substrate for algal photosynthesis, it has been hypothesised that macroalgal growth and biomass may increase, potentially out-competing the corals, contributing to reef degradation. Using controlled experimental manipulations of CO2 we are testing these hypotheses in a range of algae and corals from the Great Barrier Reef.

Projects:

  • Effects of ocean acidification on coral algal interactions. PhD student Carlos Del Monaco, Griffith University.
  • Impacts of macroalgae on high latitude corals. PhD student Patrick Gartrell, Griffith University.
  • Ecological competition between corals and macroalgae in a high carbon dioxide world: understanding the mechanisms and implications for reef ecosystems, ARC Discovery (Diaz-Pulido, Mumby, Hay, Anthony; 2012-2014).
Carlos & Guillermo, Coral-algal surveys

Carlos & Guillermo, Coral-algal surveys

Corals & Algae

Corals & Algae

Coral Halimeda

Coral & Halimeda

Lord Howe Island