It's one thing to have swarms of giant jellyfish or squids preying upon local commercial fish populations; it's quite another to have a huge swarm of crustaceans - tiny ones at that - threatening to destroy an entire island. The uninhabited island of Hoboro, which lies about 1,650 ft off the coast of Hiroshima, has been under steady attack for the last few years; millions of crustaceans - relatives of crabs and shrimp known as "nanatsuba-kotsubumushi" - are boring into the island, a process dubbed "bio-erosion."
The surge in numbers was sparked by recent increases in the temperature of the surrounding waters, which contributed to huge plankton blooms - a staple of the voracious crustaceans. "The creatures make holes in the rock as they make nesting areas, which makes it weaker and very susceptible to weathering from the ocean and the wind," explained Yuji Okimura, an emeritus professor at Hiroshima University.While the island's longstanding decline is nothing new to observers, the speed with which the crustaceans have bored into its soft rock over the past two years has caught many by surprise; Okimura noted that it would typically take several thousand years for normal weathering processes to reduce the island to rubble. Some are warning that under present conditions the island could be gone within the span of a century.