The unusual red tide that has recently affected waters off China's southern island province of Hainan has entered the final phase of its life cycle and is expected to dissipate soon, according to authorities.

The Hainan Marine Disaster Emergency Office said on Wednesday that, based on field surveys and the current development of the algal bloom, the red tide event is now approaching the end of the maintenance stage and is expected to soon decline naturally. Heavy rainfall or the arrival of a tropical storm could accelerate the process by dispersing and diluting the algal bloom.

Marine scientists have identified the organism responsible for the outbreak as a species closely related to Margalefidinium polykrikoides,formerly classified within the genus Cochlodinium, although further taxonomic studies are still underway.

Lü Songhui, a marine biologist from Jinan University in Guangzhou City, said the organism differs from previously documented red tide species found in Chinese waters and has never before been recorded in Hainan. He added that scientists cannot rule out the possibility that it represents a previously undescribed species.

Red tides generally fall into two categories: toxic blooms that pose direct risks to human health and harmful algal blooms that primarily threaten marine ecosystems. According toLü , the recent Hainan red tide falls into to the second category.

The dominant algal species causing this red tide produces compounds that damage fish gills, impairing respiration and leading to mass fish mortality when cell concentrations become sufficiently high.

However, researchers say that the toxins are not known to accumulate in fish tissue, suggesting the risk to human health remains relatively limited.

According to Lü, seafood harvested from affected waters can be consumed provided it passes routine food safety inspections. Dead or decomposing fish should not be collected or eaten under any circumstances.

Dense concentrations of algae release large amounts of mucus, which may cause skin irritation or allergic reactions, and the public is advised to avoid entering seawater that shows any unusual discoloration.

Hainan has historically experienced fewer red tide events than most of China's coastal provinces, making the current outbreak "particularly unusual".

For a red tide to develop, experts say two conditions must coincide: the presence of bloom-forming algae and environmental conditions that allow the organisms to multiply rapidly and accumulate in large numbers.

As the affected waters are part of an open marine system and no major pollution incidents have recently been reported in the area, researchers believe that this outbreak is closely linked to the persistent hot, dry weather that has affected Hainan in recent weeks.

Lü explained that prolonged high temperatures promote strong thermal stratification in the upper layers of the ocean, allowing algae to concentrate near the surface where sunlight is most abundant. At the same time, water circulation patterns in the Beibu Gulf to the northwest of the island province transport and concentrate algal cells along Hainan's western coast. Scientists believe the combination of unusual climatic conditions and regional ocean currents created the conditions for this exceptional ecological event.

Researchers also note that no universally accepted or consistently reliable early-warning model currently exists for forecasting harmful algal blooms worldwide.

Lü proposes that Hainan should expand long-term monitoring and conduct more systematic research on the harmful algal species most commonly found in local waters. By creating a comprehensive database and improving scientific understanding of algal bloom dynamics, researchers hope to develop a region-specific forecasting system capable of providing more accurate early warnings for future red tide events.