The intertidal zone can be a harsh environment, presenting many challenges to the organisms inhabiting it. Given its dynamic nature, it is surprising that it is sometimes able to sustain systems as delicate and sensitive as coral reefs. Many organisms have adapted to life on the intertidal reef flat, and one of the most prominent on the northeastern coast of Australia is the massive coral Goniastrea aspera. The mechanisms driving the distribution of this species are not entirely understood; this study investigated the potential role of microhabitat, as well as that of actual physical characteristics of the colonies, in the distribution of G. aspera on a distinctly zoned intertidal reef flat on Magnetic Island.
General distribution was determined using transects, and data was collected about the distance from shore, size, morphology, substrate attachment, and health of each individual colony. Quadrats were used to estimate the percent cover of different substrate types within the individual microhabitat. G. aspera was found to occur in highest densities in the coral-rubble zone, with an apparent preference for certain substrate types; however, selection of these microhabitats did not have a significant effect on the health of the colonies. Zone was found to influence the amount of bleaching in individuals, while distance from shore was the most important factor influencing substrate attachment, and in turn, substrate attachment had the most influence on the percentage of living coral tissue in each individual colony. The distribution and health of the colonies was found to be influenced by many different factors of both the environment and the coral itself. Microhabitat and competition are hypothesized to play key roles in density and health of G. aspera on the reef flat, with physical characteristics also having an influence, but further research into these interactions is needed to verify the exact role each one plays.
Natural Resources Management and Policy | Oceanography
Smith, Julia, "Factors Affecting the Distribution and Health of the Intertidal Coral Goniastrea aspera on the Reef Flat in Geoffrey Bay, Magnetic Island" (2006). Independent Study Project (ISP) Collection. 327.