Coral reefs are important ocean habitats and offer a compelling case of the risks of climate change. Reefs provide a large fraction of Earth’s biodiversity—they have been called “the rain forests of the seas.” Scientists estimate that 25 percent of all marine species live in and around coral reefs, making them one of the most diverse habitats in the world.
Coral reefs are fragile and sensitive to changes in water quality and temperature. When pollution causes changes in water quality or temperatures exceed their natural tolerances, corals will become stressed and may die if conditions don’t improve.
Stressors to coral reefs include:
Rising water temperatures: Corals thrive in relatively warm water, but when water temperatures rise too high, the zooxanthellae are forced to leave. Since these algae give the corals color, when they leave the coral becomes white, appearing bleached. This coral bleaching can cause the reef to die.
- Ocean acidification: Ocean acidification can affect coral health by making less calcium carbonate available in ocean waters, making it harder for corals to form their skeletons.
- Predation: Some species can cause damage to coral reefs, like damsel fish and crown of thorn starfish. While they may not be invasive, outbreaks of these species can wreak havoc on reefs.
- Overfishing: Coral reef ecosystems support an abundance of species, but overfishing can deplete these populations and affect the entire ecosystem.
- Recreational Impacts: Boat groundings and anchors can harm corals by breaking or scarring them. Sunscreens that include certain chemicals, harm coral reefs and other plants and animals that live in the ocean. Protect yourself and the reef by covering up or wearing mineral-based sunscreens.
While coral reefs are a wonderful sight when on vacation in a tropical area, it’s important to remember that overfishing or recreational use can put significant stress on these delicate micro-environments. Treat them with care – don’t walk on them or try to take a “souvenir.” Our life – and those of future generations – depend on it.