SINGAPORE — Box jellyfish, which have a painful and potentially fatal sting, have reportedly been sighted in Singapore's waters, prompting the Sentosa Development Corporation and a local marine conservation group to issue advisories on swimming in these beaches.

Marine Stewards, the conservation group, highlighted several incidents in which box jellyfish were seen in the waters around Singapore in a Facebook post on Saturday (July 18).

Box jellyfish, also called sea wasps, deliver venomous stings that cause "excruciating pain" and can possibly result in death, according to the Australian Institute of Marine Science.

In the most recent incident on Friday, a girl was stung by a jellyfish while paddling in shallow waters near FOC Sentosa on Palawan Beach. The species of jellyfish has not been identified. A video posted to the Marine Stewards Facebook page showed the jellyfish, and thin, red lines on the girl's leg.

On Thursday night, a box jellyfish was spotted from a boat around the Pulau Seringat and Lazarus Island dock, according to the Facebook post. Its total length, including its four tentacles, measured about 20cm.

On Tuesday night last week, another box jellyfish measuring about 50cm to 60cm was spotted from a boat in the Tuas area.

On July 3, a box jellyfish more than 1m in length was seen around One Degree 15 Marina Sentosa Cove. Marine Stewards said that the organisation alerted authorities after this sighting and advised swimmers to avoid the Sentosa area for two weeks.

In an earlier incident on March 21, a woman was stung by a box jellyfish while swimming in the waters off National Sailing Centre at East Coast Park. In her Facebook post, the woman reported that after she was stung, the muscles in her back, hips and shoulder went into spasm and she was immobilised.

She said that she had difficulty breathing and all her lymph nodes started swelling. A friend swimming with her handed over a buoy and towed her to shore. The incident left red marks on the woman's arms and legs.

These reports of jellyfish sightings have not been independently verified by CNA.

In response to queries by CNA, the National Parks Board (NParks) said it is aware of the reported sightings of box jellyfish in Singapore's waters.

"NParks is working together with our Friends of Marine Park group to alert the relevant stakeholders such as the academic, boating and recreational communities, as well as agencies whose staff work in and around the coastal waters, on the sighting," said Dr Karenne Tun, director of the coastal and marine branch at NParks' National Biodiversity Centre.

The agency is also working with academic partners from the National University of Singapore to collect water samples from various coastal areas to run environmental DNA analysis. This will help to detect the presence of the species in these areas, said Dr Tun.

Box jellyfish are highly venomous, added Dr Tun. Its sting is extremely painful and can cause severe hypertension, extreme lower back pain, nausea, cardiac and respiratory arrest. It can also cause fatalities.

"If stung by a jellyfish, one should rinse the affected area with seawater or vinegar and not try to remove the tentacles, and seek medical attention immediately," said Dr Tun.

Members of the public should not handle the jellyfish, and should call the NParks helpline at 1800-471-7300 if they spot one, she added.

In response to queries by CNA, Sentosa Development Corporation said that it has issued an advisory to guests advising them to be alert when swimming.

Signs have been placed along Sentosa’s beaches to alert guests to jellyfish sightings. The advisory added that beach patrol officers are conducting regular surveillance of the beaches and waters.

"For your safety, please do not attempt to touch jellyfish if you see any, and alert other beach-goers and Sentosa’s on-ground beach patrol officers (BPO) to its location.

"If stung, please do not rub the affected area nor use fingers to remove the tentacles. Please contact our on-ground BPOs for first-aid assistance," the advisory said.

Marine Stewards also advised people not to swim at Sentosa, Pulau Seringat, Lazarus Island and St John's Island for the next two weeks, the group said in its Facebook post on Saturday. CNA

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