CANBERRA, June 25 (Xinhua) -- Recent underwater footage and field surveys have exposed the devastating impact of South Australia's persistent harmful algal bloom, as scientists report widespread reef damage and mass mortality of marine invertebrates.
The persistent bloom, dominated by toxic Karenia dinoflagellates, has been active since early 2025 and continues to devastate marine ecosystems across large stretches of the state's coastline, according to a release on Tuesday from the Queensland-based Great Southern Reef Foundation, which conducted the research with Flinders University in South Australia.
Marine researchers report that sessile invertebrates, including sponges, ascidians, corals, and razor clams, have suffered near-total mortality at most surveyed sites. Mobile species such as abalone, urchins, and fish show patchier impacts, with both dead and surviving individuals observed, the release said.
Some resilient species, like rock lobsters and harlequin fish, persist in certain areas, but the long-term outlook for these populations remains uncertain, it said.
The bloom has caused mass die-offs, discolored waters, and oxygen-depleted zones, disrupting marine habitats and harming local tourism, with communities reporting foul odors, reduced beach use, and health concerns, according to the Great Southern Reef Foundation.
Scientists link the bloom's scale and persistence to marine heatwaves, nutrient runoff, and calm seas, noting its movement through the water has complicated response efforts. ■
