10-05-2025
Council shuts down popular ocean pool inundated with 'hundreds' of 'toxic' creatures
Swimmers and beachgoers have been told by council to stay away from a popular pool along the Aussie coast after it was inundated by "hundreds" of ocean creatures. The sea hares, a type of marine mollusc, were found congregating at Mereweather Baths in Newcastle, in an incredibly "rare to witness" event.
City of Newcastle council said the marine creatures, usually found in rock pools and sea grass beds, have come together to spawn in the pool which is currently closed to visitors to protect the species.
A special warning to pet owners was issued to stay away from the area as the molluscs are toxic to dogs — with one vet telling Yahoo News that the animals will exhibit "immediate symptoms" if they've touched one of the molluscs.
"This kind of mass aggregation is rare to witness in a public swimming facility, and we're working with marine experts to manage the event with care," a council spokesperson said.
"Sea hares may naturally move on with the tides, but we are also preparing to manage their removal sensitively, as well as the egg masses, to protect both the animals and the environment," council said.
The pool will be closed until at least Tuesday when council plans to "manually remove" the sea hares before pressure cleaning the pool. "We will be doing this in a careful way to maximise egg survival," council assured residents.
Sea hares are soft-bodied marine molluscs that feed mainly on algae.
It's understood that the species most prevalent in the pool is the Aplysia juliana, a common coastal species — but there are also a few larger individuals, have been identified as Aplysia sydneyensis.
They are larger than a bluebottle, growing up to 30cm long and release a dark purple ink when disturbed.
During spawning, they release long strands of yellow egg masses. Once the spawning is complete, the sea hares naturally die.
Previously speaking to Yahoo News Australia, Dr Tim Hopkins from Northern Beaches Emergency Vet, who specialises in toxins, urged pet owners to avoid areas after mass beaching events after hundreds of dead sea hares were found along the shores of the Hardy Inlet, near Flinders Bay in Augusta in Western Australia in March.
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Hopkins said symptoms can come in quite quickly in dogs in particular and the best thing to do if ingestion occurs is to seek out the nearest vet. "You'll see immediate symptoms from them having mouthed the sea hare, and then usually within hours, you're seeing those systemic signs," he told Yahoo.
"It's often hard with these inquisitive dogs, they'll find a random washed up item or animal and we do see that [poisonings] sometimes after mass beaching events with jellyfish and other venomous animals.
Their toxicity comes from their diet — primarily red and green algae — which contain compounds that can be harmful if ingested. The ink contains a mix of secondary metabolites, some of which can be irritating or toxic to other marine organisms.
Symptoms in dogs can include vomiting, drooling, lethargy, tremors, seizures and death in severe cases. While not all sea hares are equally toxic, ingestion is risky, and pet owners are advised to keep their animals away from these creatures when they wash up.
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