Mass algal bloom kills thousands of sea dragons, pipefishes and seahorses in South Australia

Thousands of sea dragons, pipefishes and seahorses have washed up along South Australia’s coastline after a severe algal bloom caused a mass mortality event that ecologists say is the worst ever recorded for the Syngnathidae family worldwide. Analysis of citizen‑scientist records compiled by the volunteer group Dragon Search SA identified more than 1,600 weedy and leafy sea dragons, 1,400 pipefishes and 160 seahorses dead on beaches as the harmful algae spread across the state’s shores.

The unprecedented die‑off highlights the ecological impact of the bloom, which has devastated marine habitats and raised concerns about future environmental health in the region. Researchers are using the citizen‑science data to assess the full extent of the loss and to inform mitigation strategies, while climate and environment editor Adam Morton continues to track the story through live updates and his Clear Air newsletter.