SAN JUAN, Puerto Rico >> An environmental group filed a lawsuit Monday accusing the U.S. government of failing to protect 12 endangered coral species across the Caribbean and the Pacific Ocean that have been decimated by warming waters, pollution and overfishing.

The Arizona-based Center for Biological Diversity said it filed the lawsuit against the National Marine Fisheries Service more than two years after the agency proposed to protect more than 6,000 square miles worth of coral habitat but never did so.

The critical habitat designation would cover 5,900 square miles off Puerto Rico, the U.S. Virgin Islands, Florida and the northwestern Gulf of Mexico. It also would cover 230 square miles around islands including Guam and American Samoa in the Pacific.

Such a designation could improve water quality in the coastal zone, limit excessive fishing and protect spawning grounds, according to the environmental group, which said “absent bold and immediate action” coral reefs worldwide could collapse over the coming century.

A spokeswoman for the National Oceanic and Atmospheric Administration Fisheries said the agency does not comment on litigation.

The Caribbean has five endangered species of coral, including the mountainous star coral, which is largely brown with fluorescent green streaks, and the pillar coral, which was moved from vulnerable to the endangered category in December. The other seven endangered species in the Pacific include the acropora jacquelineae, which resembles a flat plate that can grow up to three feet (1 meter) long.

Corals worldwide have suffered die-offs from pollution, diseases, acidification, over-fishing and an event known as “coral bleaching,” which is caused by warming oceans as a result of climate change.

Overall, 23 coral species, which are the building blocks of reefs, are listed as endangered and six as critically endangered, according to the International Union for Conservation of Nature.