Ballast Blog – Invader of the Week – Cyanobacteria

Malin Group Ballast Blog

This weeks article looks at the blue-green algae known as cyanobacteria. Cyanobacteriea is a type of photosynthetic bacteria which can be found in almost every terrestrial and aquatic habitat on earth.

It can be said that this simple one-celled organelle deserves a lot of credit. Oceanic cyanobacteria became the first microbes to produce oxygen by photosynthesis around 2.3 billion years ago, making them the tiny culprits for the Great Oxygenation Event which occurred  200 million years later, which led to earths atmosphere changing from a reducing atmosphere into an oxidizing one. This meant that the majority of earths anaerobic organisms became extinct, and the stage was set for the evolution of aerobic organisms on earth – like us humans.

However, aquatic cyanobacteria are known for their colourful blooms that can often be seen from space. Troublingly, these blooms are known to sometimes produce harmful cyanotoxins. Florida is the latest place to suffer the effects of a cyanobacteria bloom, which has come in the form of a toxic green sludge which has killed fish, shellfish, at least one manatee to date, and caused illness in several people.

What is causing the increasing occurrence of cyanobacteria blooms worldwide? There are a number of factors, with climate change featuring at the top of the list. As the water gets warmer, toxic algal blooms proliferate worldwide. One study conducted in Germany concluded that further increase in water temperature would promote the northward expansion of cyanobacteria and lead to an increase of cyanotoxins.

The presence of invasive species can also be a contributing factor. Certain invasive species, such as the European Fan Worm, excrete nitrogen – which encourages the growth of algal blooms.


(Photo courtesy of Mark Conner)