The waters around Sydney, Australian turned red yesterday morning, causing some concern that there had been a shark attack and prompting the closure of three popular beaches in the area while officials investigated. After testing the water, the culprit in this pseudo-prophetic vision was identified — an algae known as Noctiluca scintillans, or 'Sea Sparkle'.
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Similar to what happened in southern France a few months ago, the Noctiluca scintillans had a population explosion — also called 'a bloom' — as they went into a feeding frenzy on plankton and rapidly multiplied. According to the The Australian, a spokesman for the New South Wales Office of Water said that these blooms are often caused by an upwelling of colder, nutrient-rich water, and that they are common in the spring and fall, due to warmer waters and movement of ocean currents.
Although these algae blooms are a bit disturbing to look at and have an unpleasant smell, they aren't toxic and generally only represent a mild skin irritant, due to higher levels of ammonia excreted by the algae (yes, algae pee).
The blooms started to break up later in the day, allowing Bondi Beach to be reopened, and Dr. Fred Gurgel, a professor of marine biology at the University of Adelaide, told The Herald Sun "It should clear up in less than a week."
Before this bloom dissipates completely, the people of Sydney could be treated to an interesting show. The reason why Noctiluca scintillans is also called 'Sea Sparkle' is because it is bioluminescent. If the algae is disturbed, by a swimmer or a boat or even the waves or ocean currents, it can light up, producing a sparkling blue phosphorescent display for anyone nearby.