A $100 million oyster industry is in jeopardy, as a Karenia mikimotoi algal bloom,sweeps through parts of the South Australian Coastline.
In addition, hundreds of species were lost, marine tourism has nosedived by at least six figures in weeks.
The bloom has caused discoloured water and foam along parts of Fleurieu Peninsula, Kangaroo Island and the southern coast of Yorke Peninsula.
So authorities from the Department for Environment and Water (DEW) as well as the Department of Primary Industries and Regions (PIRSA), have conducted water tests in the Coorong North Lagoon.
Results have confirmed the presence of the Karenia strain of algae, in the Coorong North Lagoon between Seven Mile Basin and Long Point.
Experts believe the algae flowed through the Murray Mouth and into the lagoon during a strong cold front, including a storm on May 26 and high tide on May 27.
More tests are being conducted.
Weekly testing of the Coorong will be undertaken to analyse the algal bloom’s movement. The Coorong region remains open and visitors are advised to check signage and avoid contact with discoloured water, foamy water, or water where marine life is dead or in poor health.
Latest statewide observations show sea surface temperatures are decreasing in shallow coastal and gulf waters due to seasonal cooling and the passing of the cold front.
However, moderate marine heatwave conditions continue across most of South Australia’s coastal regions.
Experts believe there are three plausible contributing factors causing the bloom, which started in March. A marine heatwave that started in September 2024 – with sea temperatures about 2.5°C warmer than usual – combined with calm conditions, light winds and small swells. The 2022-23 River Murray flood, washing extra nutrients into the sea and cold-water upwelling in summer 2023-24 that has brought nutrient-rich water to the surface.
The last large event of this type of algae recorded in SA was at Coffin Bay in 2014.
Picture: Supplied