Algal blooms are common seasonal events in North Queensland's coastal environments between August and December when increased temperatures, sunlight and other environmental factors are favourable to growth.
Algae play an important ecological role in marine and estuarine environments. Some blooms have the potential to be harmful to humans and other animals while other blooms may only cause a nuisance impact such as an unpleasant odour.
In North Queensland, the most common naturally occurring algal blooms are caused by Trichodesmium species. This alga generally isn't harmful but can be unsightly and smell quite ‘fishy’.
Identification: Trichodesmium species washed ashore may appear red, brown, blue, green or even purple colours. On the sea surface, it can look a bit like sprinkled saw dust or an oil/paint spill. But unlike oil if a stick's dipped into a Trichodesmium bloom it won't attach to it. Also, when a stick's removed from oil, a hole will remain in the oil from the stick but it immediately close's if the material's Trichodesmium spp. Blooms washed ashore generally disappear in a few days.
Problems: The most serious problem is that it depletes the oxygen content of the water in restricted areas like creeks closed to the sea at low tide which can kill the fish. It's also really "fishy" smelling.
Don't touch it! – Blooms of Trichodesmium spp. can irritate your skin so avoid touching or ingesting it. If you come in contact with a bloom it can easily be washed off with running water.