Brown algae off Sydney and Central Coast Beaches - Trichodesmium erythraeum

Post date: Mar 12, 2018 10:12:27 PM

Issued by Water NSW

Over the weekend (10th and 11th March, 2018) there have been multiple reports of a brown algae bloom at Sydney and Central Coast Beaches. The bloom appears as a brown slick which is often mistaken for an oil spill or pollution. Preliminary analysis of samples taken at Gordon’s Bay and Terrigal suggest that the bloom is cyanobacteria Trichodesmium erythraeum.

Trichodesmium erythraeum may release toxins in the water that can cause skin and eye irritations. General advice is to avoid swimming in the area and avoid contact. Trichodesmium sp. is a tropical cyanobacteria that comes down the coast in the Eastern Australia Current (EAC). The persisting warm waters off the coast suggest that the EAC is still flowing strongly and impacting upon the shelf and into shore. It can be observed as red brown slick of saw-dust like particles at the water surface. Aggregations such as along shorelines it can turn the water milky brown to red. Generally these blooms dissipate with changing tides and or wind conditions and might be observable as slicks for hours to days at a time.

As the blooms moves along the coast some beaches may be impacted. Palm Beach was closed by council lifeguards as a precaution early on Monday morning 12th March today.

Contact Water NSW for more information P: 02 9865 2559, www.waternsw.com.au.