Trichodesmium

Trichodesmium, or "sea sawdust", is a genus of filamentous cyanobacteria. They are found in nutrient-poor tropical and subtropical ocean waters.

Trichodesmium
Trichodesmium bloom off the Great Barrier Reef
Scientific classification
Domain:	Bacteria
Phylum:	Cyanobacteria
Class:	Cyanophyceae
Order:	Oscillatoriales
Family:	Microcoleaceae
Genus:	Trichodesmium Ehrenberg ex Gomont, 1892
Species
Trichodesmium contortum Trichodesmium erythraeum Trichodesmium hildebrandtii Trichodesmium radians Trichodesmium tenue Trichodesmium thiebautii

They are most common around Australia and in the Red Sea, where they were first described by Captain Cook.

Trichodesmium is a diazotroph; that is, it fixes atmospheric nitrogen into ammonium, a nutrient used by other organisms. Trichodesmium is thought to fix nitrogen on such a scale that it accounts for almost half of the nitrogen fixation in marine systems globally.^[1][2]