Bioluminescence in the River Derwent at Montagu Bay, April 2021. Photo: Jenny Kathy, Bioluminescence Tasmania.

Bioluminescence in the River Derwent at Montagu Bay, April 2021.

Image: Jenny Kathy, Bioluminescence Tasmania

Bioluminescence is a natural light phenomenon, created commonly by the marine organism Noctiluca scintillans (a dinoflagellate) that can also produce a red tide. Many other marine species, e.g. fish and squid, also produce bioluminescence, while the phenomenon is much rarer on land.

The purpose of emitting light varies greatly. It includes finding partners and luring or illuminating prey. It can also be used as a form of defence by warning, blinding or distracting a predator. With bioluminescence occurring in so many different types of organisms, scientists are still learning about the multitude of functions it serves.

The actual process of bioluminescence is a chemical reaction that requires oxygen and a light-emitting molecule called ‘luciferin’ in conjunction with a catalysing enzyme. Bioluminescence is NOT the same as phosphorescence. In phosphorescence, external energy from a source of light is absorbed and re-emitted as a particle of light. In bioluminescence, the light-producing chemical reaction occurs inside the light-emitting organism.

Noctiluca scintillans is considered a nuisance species, but is not regarded as harmful to humans, even though large blooms are best avoided for recreational swimming (because of skin irritation).

While we enjoy the, now common, spectacular light of bioluminescence, it is unfortunately a sign of our changing climate. A strengthening of the East Australian current is pushing warm water south towards Tasmania. Our waters are now warm enough for Noctiluca to survive here all year round, and they are competing with zooplankton and larval fish for food.

Further information