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'Spreader' alter ego: Killer Algae

The most threatening of comic book villains can escape captivity, be it a prison or a mental asylum, no matter the security level, and for killer algae the tale is no different.

In 1984, killer algae — a mutant strain of the tropical seaweed Caulerpa taxifolia — allegedly escaped from Monaco's Oceanographic Museum (ironically, under the directorship of Jacques Cousteau at the time) when an employee discarded aquarium waste into the nearby Mediterranean Sea. Had it been any other tropical seaweed, this may not have been an issue. But killer algae — originally "discovered" in a German zoo in 1980 — have a genetic mutation, likely induced by years of chemicals exposure and ultraviolet light. The mutation allows killer algae to withstand and thrive in colder water than usual.


So, the invasive seaweed that had once created visually pleasing aquarium exhibits throughout Europe was officially on the loose. With fronds bigger and denser than any other strain of Caulerpa taxifolia, killer algae has blanketed more than 32,000 acres of the world's oceans, including areas of California and Australia's coasts, in lush, kelly-green meadows. In addition to tolerating low water temperatures, the spread of killer algae has been aided by its rapid growth, ability to survive out of water for up to 10 days and reproduction via asexual fragmentation. Even a 1 centimeter piece of the algae — fragmented naturally or by anchors, boat motors or fishing gear — can start growing almost anywhere.

As infestations take hold, killer algae smothers existing ecosystems by outcompeting other algal species and seagrasses for light. The algae's foliage also contains the toxin caulerpenin, which, while not lethal to humans, is poisonous to most fish and causes species diversity to plummet.

Federally listed as a noxious weed in 1999, killer algae is strictly prohibited from being imported or sold in the United States. Treatment of infestations, in which stands are cut off from sunlight with tarps and pumped with chlorine, is time consuming, expensive and environmentally damaging (it took six years and $7 million to eradicate stands near San Diego and Los Angeles). Officials in the United States view stopping the spread of the seaweed before it starts as the most cost-effective management option, but as global infestations of killer algae grow with commercial shipping and tourism, this may prove increasingly unfeasible.

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