Coral reefs are among the most diverse ecosystems in the world. This biodiversity makes them a high priority for conservation. The brilliant corals of Sogod Bay, above, live in one of more than 400 marine protected areas (MPAs) in the Philippines.

MPAs help to conserve biodiversity by preventing practices like coral harvesting and dynamite fishing. Unfortunately, there are also global dangers facing coral reef habitats that cannot be withheld by MPA boundaries.

The impact of ocean acidification on corals is one of these dangers. Oceans absorb carbon dioxide (CO2) from the atmosphere. Carbon dioxide reacts with seawater to form carbonic acid. Due to increases in carbon emissions, more CO2 is entering the world’s oceans, which creates additional carbonic acid in the water.

The more acidic seawater becomes, the less calcium carbonate it can hold. Many marine species, including coral, need calcium carbonate to build their protective shells and exoskeletons. Without it, shells grow slowly and become weak. Coral reefs with breakable, slow-growing corals erode more quickly than they accrete. Reefs can disappear, and the extinction of entire species is possible.

Efforts are being made in the Philippines to increase awareness of the potential impacts of ocean acidification. However, it will take global action to decrease our carbon emissions and help to protect the world’s fragile coral reef ecosystems.

  • Sogod Bay, Philippines, where this beautiful photo was taken, is actually a collection of MPAs. Besides coral, the areas are home to animals as small as pygmy seahorses and as large as whale sharks.
  • Coral reefs cover approximately 26,000 square kilometers (10,039 square miles) around the Philippines.
  • Only 5% of corals in the Philippines are considered to be in excellent condition.
  • Coral reef ecosystems cover only 1% of the ocean, but 25% of marine creatures live in them.
  • Corals can be animal, mineral, and plant all at once! The actual coral polyps are animals. Their calcium carbonate shells are mineral. Algae, which are sometimes considered plants, live with corals and give them their bright colors.
accrete
Verb

to build up or grow together.

Noun

layers of gases surrounding a planet or other celestial body.

Noun

all the different kinds of living organisms within a given area.

calcium carbonate
Noun

chemical compound (CaCO3) found in most shells and many rocks.

carbon dioxide
Noun

greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.

carbon emission
Noun

carbon compound (such as carbon dioxide) released into the atmosphere, often through human activity such as the burning of fossil fuels such as coal or gas.

carbonic acid
Noun

chemical produced as carbon dioxide dissolves in water.

Noun

management of a natural resource to prevent exploitation, destruction, or neglect.

Noun

tiny ocean animal, some of which secrete calcium carbonate to form reefs.

coral reef
Noun

rocky ocean features made up of millions of coral skeletons.

diverse
Adjective

varied or having many different types.

dynamite fishing
Noun

practice of using explosives to stun or kill entire schools of fish. Also called blast fishing.

Noun

community and interactions of living and nonliving things in an area.

erode
Verb

to wear away.

exoskeleton
Noun

the hard external shell or covering of some animals.

Noun

process of complete disappearance of a species from Earth.

fragile
Noun

delicate or easily broken.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

MPA
Noun

(marine protected area) area of the ocean where a government has placed limits on human activity.

ocean acidification
Noun

decrease in the ocean's pH levels, caused primarily by increased carbon dioxide. Ocean acidification threatens corals and shellfish.