The 2025 harmful algal bloom (HAB) in South Australia has continued into spring, severely impacting marine ecosystems across Gulf St Vincent, Kangaroo Island, Yorke Peninsula, and Spencer Gulf.
Dominated by toxic Karenia dinoflagellates and other harmful species, the bloom has caused mass deaths of fish, sharks, rays, abalone, razorfish, crabs, and seagrass. The bloom is self-perpetuating and difficult to predict, with satellite and water sample data showing high concentrations of phytoplankton.
Ecosystem engineers like razorfish and structural habitats such as seagrass beds have been devastated, raising concerns about long-term recovery. Despite widespread mortality, some signs of resilience are emerging, with surviving species and new recruits observed in affected areas like Edithburgh.
The ecological damage is extensive, but monitoring efforts continue to track recovery and inform future restoration strategies.
“…The ecological damage is extensive, but monitoring efforts continue to track recovery and inform future restoration strategies.”
Great Southern Reef Foundation
Source: Great Southern Reef Foundation 20/10/25
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