Coral Reefs: Rainforests of the Sea
Holly Stratts
 
Unless someone like you cares a whole awful lot, nothing is going to get better. It’s not.
--Dr. Seuss, The Lorax
 
Coral reefs have been in our oceans and seas for thousands of years yet only within the last 50 years has a visual experience of the breathtaking sights of magnificent formations been accessible to most divers, thanks to two Frenchmen. During 1942-43, Jacques-Yves Cousteau and Emile Gagnan redesigned a car regulator that would automatically provide compressed air to a diver on his slightest intake of breath. They called their invention the Aqua Lung and it was marketed commercially in the United States in 1952. This device paved the way for non-scientist types to explore our last frontier.

It is estimated that the world’s coral reefs cover approximately 110,000 square miles or an area roughly the size of Nevada. Reef-forming corals most commonly are found in tropic and sub tropic waters ranging in latitude from 32° north to south and can be found extensively throughout the South Pacific, in the East Indies and the Indian Ocean to Sri Lanka, and around Madagascar on the southeastern African coast. They also form along the tropical eastern coast of Brazil, through the West Indies, along the Florida coast and at Bermuda.

Coral reefs do not develop on the East Coast of North America north of Florida and Bermuda but small patches of coral grow as far north as New England. Certain kinds of coral grow as far north as the Arctic Circle.

Corals are animals. Individual animals are called polyps that have a cylinder-shaped body. At one end is a mouth surrounded by small tentacles. The other end attaches to hard surfaces on the sea bottom. Coral animals grow rigid calcium carbonate skeletons that collectively form the reef. Corals also depend on algae (zooxanthellae) to survive and thrive through photosynthesis. This symbiotic relationship is necessary for survival of both the coral and the algae. Anything that kills the algae, such as a reduction of light needed for photosynthesis, also kills the coral. Anything that kills the coral also kills the algae.

There are three types of coral reefs. First, the fringe reef is a submerged platform of living coral animals that extend from the shore into the sea. Second, barrier reefs follow the shoreline but are separated from it by water. They form a barrier between the water near the shore and the open sea. A barrier reef may consist of a long series of reefs separated by channels of open water. Such reefs usually surround volcanic islands of the South Pacific. The Great Barrier Reef of Australia, more than 1,250 miles long, is the most magnificent coral reef in the world. Third, an atoll is a ring-shaped reef that surrounds a lagoon. In 1842, Charles Darwin first proposed an origin for these structures based on his field observations on several islands. Other hypotheses for atoll formation have been proposed, but Darwin’s theory remains the most plausible to many scientists. He proposed that atolls form from the subsidence or sinking of volcanic islands and their associated fringing reefs. The fringing reef continues to grow upward as the volcano subsides. When most of the island has subsided, a barrier reef forms encircling the island. After all of the original volcanic island has subsided, a lagoon takes its place as the circular reef pattern of the atoll forms. Storms breaking on the reef of the atoll pile material above sea level on the reef. Although many coral atolls are uninhabited, some larger ones such as Midway Island and some in the Cook Island group can support human habitation.

Dr. Sheila A. McKenna ’87 A&S has extensive experience in reef-forming coral habitats. As director of the Marine Biodiversity Program, Center for Applied Biodiversity Science for Conservation International in Washington, D.C., her expertise is in coastal management, marine science and Rapid Assessment Programs (RAPs) in the field. As described by Conservation International, marine RAPs are short and intensive biological inventories of key marine areas around the world. “We go into areas that haven’t been investigated before. We look at three indicator groups for biodiversity that includes corals, coral reef fish and mollusks such as clams, crabs and snails. We check for reef health which I do as part of the reef condition team. We look at the benthos to determine what percentage of different species covers the bottom. The indicator is how much live coral coverage is present. We also look at the commercially important fish, what the fish populations are and what their biomass is. All this gives you a good indication of the condition of the reef.”

McKenna has over 2,500 dives in Indonesia, the Philippines, the Bahamas, Bermuda, the Galapagos Islands, the Cook Islands, Madagascar and St. Croix. Not all of these expeditions go according to plan however. During a trip to Madagascar, McKenna and her team were trapped there when a civil uprising occurred following a national election. No one was permitted to enter or leave the country for a week.

“These expeditions are usually conducted in conjunction with a socio-economic team that goes into the villages and discovers what marine resources are used in the local area and what their concerns are. All this information is synthesized and used to help pinpoint and set up locally managed marine areas and also determine ways they can best preserve the biodiversity. The locally managed marine areas work well because it shows the people that their catch is better when an area is not fished for a while or a specific section of reef is closed off for a while and left to reestablish healthy stocks of fish,” noted McKenna.
Dangers facing reefs

Coral reefs around the world are in danger and this danger comes from many fronts such as overfishing, coral bleaching, coastal development, global climate change and human-related activities.