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Can a remote island sustain its own ecosystem?


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In Life of Pi, Yann Martel describes a floating island of vegetation with its own ecosystem that could be boarded and had animals living on it out in the middle of the ocean. It seems far-fetched, but does anything like this exist? —Tim M., UK

Not to deprecate the novelist's art, Tim, but Life of Pi also speaks of carnivorous islands whose trees bear fruit containing human teeth. Mini terrestrial ecosystems adrift in midocean are likewise too cool to be real. However, floating islands of more modest scope do exist, typically in freshwater where there's less wave and tidal action.

One example is the peat batteries of the Okefenokee Swamp in Georgia and Florida. These form when large masses of peat lying on the floor of the swamp accumulate enough methane and carbon dioxide to become buoyant and rise to the surface. Sometimes more than a quarter acre in extent and up to six feet thick, peat batteries can form a base for shrubs and even large trees.

Floating islands aren't limited to swamps—Ohio has its famous Cranberry Bog of Buckeye Lake, a 50-acre mass of moss formed when the floor of a valley that was flooded to create a canal reservoir in the 1830s broke loose and floated to the surface. Besides supporting the eponymous cranberry bushes, Cranberry Bog also hosts flowers, trees, and insectivorous plants, and is stable enough that folks can hike on it. The acre-sized floating island of Island Pond in Springfield, Massachusetts, moves around regularly, attaching itself to different parts of the lake as wind, waves, or humans drive it. As this example suggests, tussocks, as floating islands are sometimes called, can be a royal pain in the drainpipe—they can block waterways, destroy lakefront property values, and clog power-plant water intakes.

Loktak Lake in India, covered by yards-thick mats of drifting vegetation called phumdi, contains Keibul Lamjao National Park. This floating wildlife preserve is home to more than 100 endangered Manipur brow-antlered deer, locally known as sangai, or "dancing deer," because of the balletic gait necessitated by the island's soggy footing. Though the deer are doing OK for the moment, the habitat that sustains them is threatened by the manipulation of water levels to run a nearby hydroelectric plant.

Some floating islands are human-made. For centuries the Uros tribe of Peru has been constructing its islas flotantes on Lake Titicaca, reputedly to escape subjugation by the Inca and other tribes. Made from bundles of totora reeds grown in and around the lake, the islands literally support hundreds of families of fishermen.

In 1942 eccentric genius Geoffrey Pyke and Lord Mountbatten of Great Britain proposed what became known as Project Habakkuk: a plan to construct an immense floating island to transport fighters, long-range bombers, and artillery for use against Axis forces. No mere raft, the Habakkuk would have been 2,000 feet long and 300 feet wide, with nearly 20 times the displacement of the modern aircraft carrier Nimitz. Design specs called for the megavessel to be built of pykrete, a mixture of 14 percent wood pulp or sawdust and 86 percent ice, making it theoretically unsinkable due to its size and inherent buoyancy. Crazy as it sounds, the scheme might have worked—pykrete is cheap and strong and melts slowly. Pyke and Mountbatten got permission to build a 1,000-ton prototype chilled by an on-board one-horsepower motor and successfully floated it on Patricia Lake, Alberta. By then, however, the Allies were doing well enough with conventional weapons that the project went no further.

Since at least 1996 an urban legend has circulated about a giant reef in the South Pacific, supposedly nearly 60 feet thick, made up of millions of discarded condoms. The condom reef is bunk, but a circular current called the North Pacific Subtropical Gyre, located between the west coast of the U.S. and Hawaii, has created a floating collection of trash estimated by some scientists to be at least the size of Texas. Though the three million tons of man-made debris is spread too thin to be considered an island, it remains an ecological and potentially a navigational hazard.

Finally we have—OK, not a floating island, but I'd never forgive myself if I didn't mention the 29,000 rubber ducks, turtles, frogs, and beavers that pitched over the side of a Chinese cargo ship steaming for Tacoma in 1992. Some washed up soon enough on the coast of Alaska, but researchers predicted a portion of the remainder would pass through the Bering Strait, across the Arctic Circle, and into the North Atlantic, making landfall in England and the east coast of the U.S. by 2003. Despite media warnings of the bath-toy armada's impending arrival, only spotty sightings have been reported, so maybe it was all BS. But who knows—when the Fourth of July holiday approaches, terrified Long Island beachgoers may yet run ashore screaming, "Duck!"

Art accompanying story in printed newspaper (not available in this archive): illustration by Slug Signorino.

Update 9/11/2018: A new headline was added.

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