The shores of Tasmania’s Preservation Bay glowed blue last week, but why?
The blue light caused by billions of algae is called Noctiluca scintillans, or sea sparkle. Bioluminescent algae illuminates the water when disturbed by waves and currents.
According to Gustaaf Hallegraeff, an aquatic botany professor at the University of Tasmania, scientists believe the algae’s flashing light is used as a deterrence mechanism against predators.
“Imagine there’s a little animal that wants to eat this plankton and suddenly it flashes at you,” he said.
A deep red or orange color in the daylight, the algae only glows blue at night. The phenomenon was first reported in Sydney Harbour in 1860, but has since expanded to other regions. Hallegraeff attributes this in part to oceanic warming and currents.
Hallegraeff also explained that the threats associated with this algae are directly related to the species inhabiting the nearby ocean regions. The phenomenon acts like a vacuum cleaner, eating the plankton in its path. This has led to complaints from local Tasmanian shellfish farmers stating that their shellfish were hungry after being left with nothing to eat.
Hallegraeff did express support for the idea of the glowing algae becoming part of the tourism industry in Tasmania.
“It exposed people to the wonder of nature and they should be able to enjoy that,” he said.
Though the occurrence is nontoxic, the algae can cause skin irritation in some people.
Photo by Catalano82, CC BY 2.0
Chamberlain Smith is a freelance writer based in Athens, Georgia.