PS 10-113 - Changes in coral reef health:  A follow-up study on three fringing reefs of Magnetic Island

Monday, August 8, 2011
Exhibit Hall 3, Austin Convention Center
Matthew K. Holden, Biological Sciences, University of Arkansas, Fayetteville, AR

    Coral reefs are some of the most important ecosystems in the world in terms of biodiversity.  The richness of life and nutrients that exists within a coral reef ecosystem in an otherwise nutrient desert helps to ensure the survival of surrounding marine ecosystems while providing vital resources such as tourism, fishing, and coastal protection from storm damage.  The Great Barrier Reef Marine Park (GBRMP) is separated into several zones which help to regulate access and use of the park.  The green zone is the most protected, allowing for minimal recreational use, however; the blue zone allows for reasonable fishing and recreational use. Despite the vast importance of coral reef ecosystems throughout history and the current conservation efforts, they are still susceptible to a variety of natural and anthropogenic disturbances. 

    In this study, a general assessment of coral health on three fringing reefs located around Magnetic Island, Queensland was made and compared with past studies by recording the number of incidences of disturbance to coral colonies.  Specific disturbances recorded included bioerosion, bleaching, algal overgrowth, disease, and human damage.  Coral health was also compared between green and blue zones.  The specific corals focused on during this study were hermatypic scleractinian corals.


    The coral reef health at the sites studied considerably decreased compared to results from 12 months prior.  The average number of unhealthy coral colonies increased to over five times the amount of the previous year.  Acropora spp. branching corals and Acropora spp. tabular corals were the dominate growth forms.  Although Acropora spp. branching corals and Acropora spp. tabular corals were major growth forms, they were also the major species affected by disturbance.  Analysis of variance indicated that there was a significant difference between the number of coral colonies affected by different damage types, indicating that some species may be more susceptible to specific damage types than other coral species.  Analysis of variance also indicated that there was a significant difference in how damage occurred on each reef which illustrates that different damage types may affect one reef more than another.  Algal overgrowth and human disturbance continued to be the predominant damage types.

    Contrary to predicted outcomes, the coral reefs located within green zones were in poorer condition than reefs located within blue zones.  Increased protection and management must be implemented to ensure that further deterioration and loss of biodiversity does not occur at each of the three fringing reefs studied. 

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