Control of coral competitors, predators, pests and other invasive species is particularly important on high-value tourism reefs, or in areas where algae has overtaken coral as the dominant species. This includes controlling crown-of-thorns starfish (COTS) populations, and excess seaweed.
Although naturally-occurring, and offering positive contributions to reef ecology as a food, habitat and fish nursery, macroalgae – or seaweed – when excessive, can compete with, and threaten coral on nearshore reefs.
Its volume on reefs can increase through excess nutrients from human disturbances and pollution, such as agricultural run-off. Macroalgae can negatively affect coral by competing for space and other resources, overshading and transmitting disease. It can also reduce coral larvae production, and inhibit young coral settlement, growth and survival. Manual removal is labour-intensive.
The greatest potential for large-scale and long-term management is through nurturing biological removal agents such plant-eating urchins and fish.
Photo by J Maynard, Copyright, Commonwealth of Australia (GBRMPA)