Great Barrier Reef
When Captain Cook ran his HMS Endeavour aground here in 1770 he knew he’d hit something unusual, if inconvenient. Now we know it as the Great Barrier Reef, 1,250 miles (2,000 km) long, largest structure ever built by living creatures, visible from the moon.
More than 1,500 kinds of brilliant tropical fish make their homes in this rich ecosystem regarded as the marine equivalent of terrestrial rain forest and one of the most species-rich on earth.
Armored pinecone fish find prey with cooperation of live-in bacteria that glow green-blue at dusk. Male pipefish become “mothers,” incubating embryos in pouches and giving live birth. Amiable groupers 12 feet (3.7 m) long, weighing almost 1,000 pounds (450 kg), strike fear into divers with mock attacks—like barracuda, more curious than aggressive.
Angelfish resembling exquisite undersea butterflies probe coral niches for tiny invertebrates. Orange-white-and-black clown damselfish live painlessly among stinging anemone tentacles,protected by mucus coatings and collecting effortless meals. Bottom-dwelling gobies cohabit burrows with housekeeping shrimp which keep home digs tidy while roommates act as predator “watchdogs.”
Even the worms are beautiful—glowing purple flatworms, delicate salmon-pink feather dusters, golden-bedecked Christmas tree worms. Giant clams, one of 4,000 kinds of reef mollusks, gape velvety scarlet and purple mantles 56 inches (140 cm) wide.
Homely, endangered dugongs like 13-foot (4-m) undersea blimps munch sea grass in crystalline blue-green waters inside the reef’s protection. So do endangered green and loggerhead sea turtles, returned from undersea migrations of hundreds of miles to crawl up white coral sand beaches during summer full moons and lay hundreds of eggs. Raine Island once recorded the greatest known concentration of nesting sea turtles—over 11,000 in a single night.
Overhead, majestic white-bellied sea eagles hover along with stately reef herons, ospreys, pelicans, and frigate birds sailing on 7.5-foot (2+ m) wingspans. Some 242 bird species are supported by and on reef cays and islands, including 40 kinds of seabirds which maintain some of the most significant breeding colonies in the western Pacific—100,000 brown boobies on Heron Island, along with similar numbers of wedge-tailed shearwaters (aka mutton birds) in underground burrows. More than 100 kinds of land birds nest as well.
More than 3,400 reefs ranging in size from under an acre to more than 20 square miles (52 km2) with thousands more smaller reeflets make up this spectacular U.N. World Heritage Site. Some are barely awash at low tide, others form underwater gardens of wondrous color and design in an overall area equal to that of England, Ireland, and Wales combined—some 80,000 square miles (208,000 km2), or twice again as large if one includes surrounding sea.
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Charles Darwin, investigating reefs on his famed Beagle voyage almost a century after Cook, formed now-accepted theory of how they were formed over millions of years by tiny one-celled animals, each living symbiotically with a tiny plant cell within it. Coral furnish safehavens for plant alga, getting in return food and oxygen released when alga consume corals’ nitrogenous wastes and carbon dioxide. When they die, their skeletons support successive generations, enlarging reefs which gradually rise even as their size and weight cause earth around them to subside.
Corals of some 350 species live on the reef in hues and forms as diverse as any in the natural world, from purple sea fans to huge convoluted brain corals, golden and lilac staghorns, pink mushrooms, and crimson sea whips, each home to a profusion of other plant and animal life. Each spring they witness and provide one of the natural world’s spectaculars, an explosion of underwater visual fireworks when millions of coral simultaneously spawn one or two nights after a full moon, releasing trillions of pink, red, and orange egg and sperm bundles to find one another and form new generations on their ancestors’ ancient homes.
Reef climate is tropical with warm temperatures, high humidity, and variable rainfall, most ofit in summer with monsoon (southwest wind) season. Air temperatures range between 75–86°F(24–30°C) in midsummer (January), dropping to 64–73°F (18–23°C) in July. Reef waters’ temperatures vary seasonally.
Natural threats range from cyclonic winds with huge waves which destroy fragile reef structures to freshwater runoff after heavy rains, which can reduce salinity to coral-killing levels.
Longer-lasting are human threats—oil drilling and exploration, for which permits were issued but are for the present suspended; unsustainable commercial fishing and bottom trawling; tourist impact from boat discharge of waste, litter, and fuel, plus direct physical damageby anchors, reef-walking, and disturbance of fauna; illegal collecting of coral; and deteriorating water quality in runoff from populated areas. It’s thought sporadic outbreaks of coral-eating crown-of-thorns starfish may be due to ecological imbalance caused by human activity.
Coral have delicate temperature requirements. Water below 63.5°F (17.5°C) has adverse effects—but global warming could be even more devastating. Even slightly higher temperatures can cause fatal reef-bleaching due to stress which causes coral to expel their life-giving plant partners; rising water levels would force some below the level where sunlight permits algal photosynthesis.
There are a number of ways to visit the reef. International jets fly to Sydney or Brisbane, from which connecting flights go to various coastal towns—Cairns, Townsville, Mackay, and Rockhampton, among others. Or go by bus, rail, or hire a car and drive along the coast stopping at points which offer pleasant lodging and day trips to the reef, and visit mainland national parks along the way.
Accommodations, both mainland and island, range from adequate to luxurious, or one cancamp inexpensively (with permit). See the reef by glass-bottomed boat, snorkel, or scuba. Serious sun protection is a must both in and out of the water. Wear a T-shirt and bring sandals and old tennis shoes for sharp coral sand.
Off Airlie Beach are the Whitsunday Islands and the outer reef. Off Townsville are Hinchinbrook, Magnetic and Orpheus Islands. Off Cairns are Bedarra, Dunk, Fitzroy, Green, Hinchinbrook, Lizard, Thursday, and Orpheus, the Low Isles, many outer reef areas.
One of the best places for breeding seabirds is Michaelmas Cay, a day-trip off Cairns. Lizard is known for superb diving and snorkeling and fine beaches, with upscale lodging but also camping. Hinchinbrook is Australia’s largest island national park, mostly untouched wilderness with goodis Australia’s largest island national park, mostly untouched wilderness with goodlodging, campsites, spectacular rain forests, and granitepeaks off long sandy beaches with a glorious coastalwalk. Heron has good lodging (no camping), outstandingbirds, and surrounding waters teeming with life.
The Whitsundays are great for sailing with lodgingto suit all budgets. Lady Elliot has simple lodging,camping, fine diving directly off the beach. Orpheush as luxury accommodations with wonderful shells on beach and all the reef attractions.