Coral reefs under pressure from damselfish


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A loss of the primary microhabitat of the Threespot damselfish, Stegastes planifrons, has forced the species to seek out new territories.

Due to the damselfishes territorial nature, and feeding habits, this shift in distribution has an adverse affect and pressure is being put on the reef as the fish now destroy corals from the Montastraea annularis species complex. 

It was previously thought by marine scientists that a lack of predators due to overfishing was the reason that the damselfish swarmed coral reefs. However, a new report has discovered that this is not the case. In fact, it is the loss of the fishes preferred habitat that is the problem.  

S. planifrons favours setting up home among staghorn branching corals, particularly Acropora cervicornis, upon which S. planifrons create algal farms on the skeletons of corals after biting into the living tissue.

Although Acropora species can grow fast enough to withstand the effects of these cultivations, the much slower growing M. annularis species cannot recover as quickly and may even take hundreds of years to fully recover.  The actions of the fish affect not only coral mortality but also algal dynamics throughout the Caribbean.

The mass mortality of Acropora can be attributed to factors such as predation, hurricanes and white band disease - white band disease alone has been attributed to wiping out 95% of all Acropora corals in the Florida Keys alone, and all these factors have dramatically reduced the presence of Acropora species since the 1970’s.

The report demonstrates that the answer to the problem should centre around restoring the lost habitats of Acropora species, and not relying upon relieving the pressure on fishing for predator species of the damselfish, such as groupers and snappers.

For more information see the paper: Precht WF, Aronson RB, Moody RM, Kaufman L (2010) Changing Patterns of Microhabitat Utilization by the Threespot Damselfish, Stegastes planifrons, on Caribbean Reefs. PLoS ONE 5(5): e10835. doi:10.1371/journal.pone.0010835