The Department of Water identified significant levels of an algae species, known to be involved in fish kills, in the Vasse estuary in recent weeks.
Although no fish deaths were observed, the Department of Water was closely monitoring the waterways and investigating possible causes for the elevated algae levels.
Karlodinium is an algal species which occur naturally in low levels in ecosystems worldwide.
In some cases, the species could form an intense bloom, which as it dies and breaks down, releases fish-killing toxins into the water.
Blooms of karlodinium species have occurred annually in the Vasse estuary since 2013, however the concentrations have been much lower than detected this week.
Dr Kath Lynch from the Department of Water said karlodinium species preferred stratified conditions (where the water formed ‘layers’) and cooler water temperatures that often occurred after first rains at the end of autumn.
Monitoring of the Vasse estuary, however, showed no stratified conditions, with the salinity of the water close to that of seawater.
Dr Lynch said at this stage they were unsure why the karlodinium bloom had intensified.
“We are monitoring the situation and are currently working to determine what environmental conditions might have contributed to the bloom,” she said.
As a management action Water Corporation has opened the fish gates on the Vasse surge barrier to allow fish to move through the gates and dilute the bloom.
Neighbours to the Vasse estuary channel have also been notified.
The Department of Health advises against recreational activities in waterways during a fish kill or algal bloom event.
The departments greatly appreciate the support and assistance of the community and encouraged people to report any algal blooms to ALGALWATCH on 08 6250 8064. Any fish deaths should be reported to the Department of Fisheries FishWatch on 1800 815 507.
