Moen, C.

Various symbiotic relationships build and maintain coral reefs. Mutualistic relationships provide the organisms involved with an increased chance of survival and reproduction which prove important for the health and function of reef communities. The increasing presence of macroalgae is an indication of declining reef health. In order to maintain the growth of certain species of macroalgae, Threespot damselfish, Stegastes planifrons, cultivate and maintain algae gardens. If there is an abundance of algae in the gardens of S. planifrons, there is a limited opportunity for coral recruitment and growth; this makes them an important species in the ecosystem. Damselfish are very territorial and will defend their gardens by chasing and biting intruders. This study tested whether there is a particular sized territory surrounding the garden that correlates to the size of the garden itself. Attacks by S. planifrons in the gardens toward a laser pointer allowed the determination of garden and territory area. The area of the garden, the point where the attacks ended and the total surrounding territory of the damselfish were measured using a measuring tape. A positive trend between area of garden and area of territory was found indicating that both increased correspondingly. The algae gardens and territorial behavior of S. planifrons can be indicative of the current phase shift from a coral reef to a coral depauperate ecosystem. More algal cover is indicative of decreased coral cover and coral recruitment success. By understanding ecological dynamics, protection of coral reefs from a degrading phase shift can be implemented.

This student research was retrieved from Physis: Journal of Marine Science XIV (Fall 2013)19: 96-102 from CIEE Bonaire.