Toxic tides and marine collapse: Lochie Cameron tracks South Australia’s algal disaster
In early 2025, vast stretches of South Australia’s coast began to turn silent. Marine life washed up on beaches in unprecedented numbers—sharks, rays, sea dragons, and fish lay lifeless along the sand. Beneath the surface, the ocean floor transformed into a desolate wasteland. At the center of the response was Lochie Cameron, a marine observer and citizen science leader who has spent months documenting one of the most devastating algal blooms in Australian history.
The bloom, dominated by the toxic species Karenia mikimotoi, first surfaced near Goolwa and Middleton in March after swimmers reported eye irritation. From there, it expanded rapidly, engulfing the Gulf St Vincent and progressing into the Spencer Gulf. Covering an estimated 4,500 square kilometers—roughly 30% of the South Australian coastline—the bloom has impacted waters up to 30 meters deep, killing marine species across every level of the food chain.
Algal blooms are not new to South Australia and can often drive healthy marine productivity. But this event was different. Driven by a rare convergence of environmental conditions, it became a toxic, self-sustaining crisis. Unusually warm waters, the nutrient-rich Bonney upwelling, and agricultural runoff from the 2023 Murray River floods created an ideal environment for harmful algae to thrive. As marine organisms died, their decomposition fed the bloom further, accelerating its spread and impact.
Lochie, who also manages a caravan park and works as an aquatics instructor, began documenting the event as it unfolded. He and hundreds of other citizen scientists contributed to an iNaturalist project cataloguing marine deaths along the coastline. The scale was staggering—tens of thousands of southern fiddler rays, Port Jackson sharks, flathead, and other benthic species washed ashore. In one stretch of beach, there were 87 dead weedy sea dragons recorded across just three kilometers.
This Harmful Algal Bloom is totally devastating; the toxins are affecting species on all trophic levels.
Lochie Cameron, Citizen Scientist.
The cause of death in many cases has been linked to the algae’s toxins, which damage the gill structures of fish and invertebrates, leading to suffocation. In other cases, neurotoxic effects have been suspected. Strange behaviors observed in sharks and rays—beaching themselves repeatedly, swimming erratically—suggest neurological damage. Marine mammals, including dolphins and seals, have also been found dead. One necropsied dolphin showed signs of starvation, hinting at broader ecosystem collapse.
Much of the devastation remains hidden beneath the waves. Divers report that once-thriving marine habitats, such as Edithburgh Jetty—famed for its soft corals and sponge gardens—have been stripped bare. Some have described the underwater scene as resembling a bushfire. In affected areas, even fishing 20 kilometers offshore yields nothing. The entire Gulf St Vincent has become an aquatic dead zone.
The consequences have extended beyond ecology. Tourism in coastal towns has collapsed, particularly in regions like the Yorke Peninsula, where businesses have experienced an eerie absence of visitors during what would normally be a steady winter season. In the aquaculture sector, oyster and mussel farms have been shut down for months. Despite oysters’ ability to metabolize toxins over time, fear among consumers has stifled demand. Commercial fisheries are reporting record-low catches. Both state and federal governments have offered $28 million in combined support, though many affected believe the funding falls far short of what’s needed.
Lochie and others in the field say this disaster is not just a product of bad luck. Climate change and human activity played a clear role. Sea surface temperatures reached five degrees above average during the summer and remain elevated. These warmer waters, combined with increased nutrient loads from agriculture and flood events, made the region highly vulnerable to a toxic bloom of this magnitude.
While some treatment methods exist—such as using modified clay to suppress algae—they come with significant environmental risks. For now, the focus is on long-term resilience. Restoration of native oyster reefs and seagrass beds, which can help filter toxins and support marine biodiversity, has been identified as a priority. South Australia once hosted extensive oyster reefs that acted as natural barriers against such events. Their return could offer hope for the future.
Despite the devastation, the citizen science response has been one of the few bright spots. Over 700 volunteers have contributed to the SA Marine Mortality Project, identifying species, logging locations, and sharing data with researchers. Some carcasses have been sent to universities for study, including sea dragons whose ear bones—called otoliths—can help determine their age and life history. Government agencies like PIRSA and Fishwatch have also played a role, collecting specimens and coordinating responses, though many teams were overwhelmed by the sheer scale of mortalities.
There are growing concerns for species that have not yet shown signs of impact but remain at risk. The giant cuttlefish aggregation near Whyalla is particularly vulnerable. These animals breed once, lay eggs, and die shortly after. If the bloom reaches their breeding grounds, it could wipe out an entire generation. Conservation groups are already discussing the possibility of collecting eggs for captive rearing to prevent permanent loss.
Marine scientists warn that what has occurred in South Australia could happen again. Blooms of Karenia species have caused ecological disasters in Japan, China, and the Gulf of Mexico. Australia is not immune, especially with rising ocean temperatures and continued nutrient loading. The coastline of South Australia, one of the most biodiverse marine algal environments on Earth, has suffered a serious blow.
Lochie believes recovery is possible—but not soon. The ocean is resilient, but the damage in the Gulf is so widespread that restoration could take decades. Toxic waters have persisted for months, and the full ecological toll is still being uncovered. What began as a local issue has grown into a long-term environmental crisis—one that demands sustained attention, funding, and political will.
While the future remains uncertain, the dedication of individuals like Lochie Cameron offers a glimpse of what committed, grassroots action can accomplish. His work has not only provided essential data to researchers but also galvanized a broader awareness of the fragility of South Australia’s marine ecosystems. In a time of ecological crisis, such efforts may prove vital to ensuring there is still something left to protect.
You can listen to the full conversation with Lochie Cameron on the Citizen Science Show Podcast