Are damselfish detrimental to Bonaire’s coral reefs?

Damselfish are small herbivores that cultivate algal gardens on coral heads throughout Caribbean reefs. These gardens are used to grow specific types of algae that they can digest easily. However, algal gardens can affect coral both physically and physiologically. In addition to competing with coral for light and space, algal gardens cause coral to spend valuable metabolic energy to remove the algae. This study aimed to determine whether there is a correlation between damselfish density, percent dead coral cover, and coral diversity. A total of thirty-two 20 x 1m belt transects were laid out randomly at a highly impacted and less impacted site. The damselfish density, the number of species, and their size distribution were recorded along with percent dead coral present and coral composition of the substrate. Data were analyzed and compared to deduce whether or not there was any significant evidence that high damselfish numbers are correlated with an increased percentage of dead coral. Although no connection was found between high densities of damselfish and increases in dead coral, it is possible that factors not quantified in this study, such as human impact, could have had an influential role on both damselfish densities and the health of the reef.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 50-56 from CIEE Bonaire.

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