Visitors to Banyule swamp may have noticed a green tinge to the water (see sample below) caused by a bloom of cycanobacteria (blue/green algae). The cyanobacterium involved appears to be a species from the genus Dolichospermum (formerly part of the genus Anabaena). Down a microscope it appears as curled filaments of beadlike cells interspersed with the ocassional gas-filled cell that makes the filament float. The bloom is likley to have been triggered by high nutrient levels and warm water. The rains and colder temperatures that have just arrived may curtail and disperse the bloom.