Cleaning the coral nursery at Phi Phi Ley Island is a monthly job that is done to ensure that the coral fragments growing in the nursery are not smothered by algae as it attempts to take over the space on the racks.
Algae grows naturally in areas of the reef that have damaged corals or areas of denuded corals. Coral can fight off attempts by the algae to over take it but during algae blooms it is difficult for the coral to maintain it’s dominance on the reef.
Herbivores, such as parrotfish, sea urchins and other echinoderms play an important role in maintaining the balance and avoiding the shift from a coral dominant phase to algae dominant phase.
In a way we are doing the job of the herbivores and increasing the probability of survival while the small coral fragments can grow to a size of self survival.
However instead of grazing we use toothbrushes and scrapers!