Thousands of Sea Dragons Perish in Devastating Algal Event

South Australia experienced one of the worst mass mortality events for the Syngnathidae family, which includes sea dragons, pipefishes, and seahorses. Analysis of citizen scientist records revealed that over 1,600 weedy and leafy sea dragons, 1,400 pipefishes, and 160 seahorses washed ashore due to a harmful algal bloom. This toxic event, identified as a rare type of algae, began in March 2025 and affected at least 13 of the state's 30 Syngnathidae species. Weedy and leafy sea dragons, found only in Australia, were among the first casualties. Records indicate that dead sea dragons continued to be found for over a year, with pipefishes and seahorses washing up mainly during the winter and spring of 2025. The conservation status of weedy sea dragons, recently upgraded to vulnerable, and the leafy sea dragon are under reassessment following this crisis. The bloom, caused by Karenia cristata, has impacted over 800 species along Australia's coast. Beyond the immediate loss of life, the event has caused extensive habitat destruction, including the loss of kelp, seagrasses, and sponges, which are vital for these animals and their food sources. Scientists and conservationists are concerned about the long-term consequences for South Australia's marine emblem and are exploring solutions such as captive breeding programs and artificial habitats. Citizen scientists and divers played a crucial role in documenting the mortalities, providing invaluable data for scientific analysis.