Defenders' Experts
Hawaiian Islands National Wildlife Refuge - Hawaii
The submerged world of coral spreads in a colorful weave of delicate calcified meadows over more than 3 million acres around the northwestern Hawaiian Islands. This marine menagerie is home to 7,000 species of coral, algae, mollusks, fish and crustaceans. In this vibrant underwater world, the endangered Hawaiian monk seal fishes for lobster and eel, repairing to sandy beaches to rest and give birth to the next generation of one of the world's most imperiled seals.
The refuge is comprised of eight islands, reefs, and atolls which provide breeding and nesting space for endangered leatherback and threatened green sea turtles. Many millions of seabirds such as great and lesser frigatebirds, Laysan albatrosses, shearwaters, boobies and terns breed here, joined by wintering shorebirds, endangered songbirds and waterfowl. In recognition of this amazing biodiversity, President Bush recently declared the vast area of ocean in which the refuge is located a national monument, making it the largest protected patch of ocean on Earth.
The Threat
For monk seals, seabirds, and coral, the remote nature of their Hawaiian Islands habitat has never fully insulated them from threats of industry and pollution. However, previous threats look small in scale compared to the warmer sea temperatures, shifting currents, sea level rise and sunken habitat projected in future scenarios.
One island is already gone, claimed, researchers believe, by some combination of intense storms and shifting sea currents. Islands are critical habitat for the monk seal, a marine mammal species reduced to only 1,500 individuals. Predictions of future sea level rise make further loss of habitat likely, another challenge to the seal's ability to reproduce. The situation is similar for the three sea turtle species that breed here and rely on the availability of suitable beach habitat to shelter their nests.
Coral species may be even more vulnerable to global warming because they require consistent ranges in water temperature. Prolonged periods of warmer water can cause bleaching, the loss of colorful algae that lives in symbiosis with coral. Stripped of this algae, coral reefs around the world that were once an explosion of vivid colors are turning a pallid gray or ghostly white and are no longer able to survive. Complicating matters is the increasing acidity of the ocean as more carbon dioxide is pumped into the atmosphere and absorbed, creating carbonic acid and depleting the seawater of the calcium carbonate corals need for growth and repair. With "temperature- induced bleaching" cited as one of the reasons, two species of coral-the staghorn and the elkhorn-were recently added to the endangered species list, the first corals to receive that dubious distinction. Scientists believe that if the warming trend continues, extinction is likely for many species of coral-along with the undersea communities that depend on them.
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