Blue dragons, thousands of dead pipis and a “big blob of super hot water”: What’s happening off the Mid North Coast?

It’s not often you see a blue dragon on Mid North Coast beaches. The small sea slugs, otherwise known as a blue glaucus, immediately grab attention for their otherworldly aesthetic. But on Thursday, residents of South West Rocks would’ve been able to see dozens washed up at the beach, stagnant on the sand. 

Experts say the unusual event is likely linked to above average ocean temperatures – a phenomenon that strongly influences weather patterns in Australia.

An expert opinion: Adrian Meder from the Australian Marine Conservation Society told the Mid North Coaster blue dragons are normally out in the middle of the ocean.

• “They live in the boundaries between two oceanic currents where food gets concentrated,” Meder said, explaining the marine creatures hang out in patches of high ocean productivity on the edge of hot and cold currents, feeding on things like bluebottles and other jellyfish.

Strong currents and winds: Blue dragons are not strong swimmers and can often be at the mercy of strong currents. Both genus of the animal (Glaucilla marginata and Glaucus atlanticus) are tiny – measuring somewhere between 1.3 and 3-centimetres. Existing near the surface of the water, sustained periods of strong winds towards the coast can lead to them being washed up on beaches.

Meder said the blue dragon visitation at South West Rocks likely has something to do with the water being unusually warmer than usual for this time of year. He explained the ocean off the New South Wales coastline is a global ocean heating hotspot.

• “One of the things that is happening right now off [the NSW] coast is water temperatures have been elevated by about three degrees above the average for this time of year,” said Meder.
  

• In 2024, a CSIRO report found Australia’s oceans are warming faster than the global average. But the oceans off south-east Australia and the Tasman Sea are a particular hotspot – and are warming at twice the global average.

• Sea surface maps show water sitting just off the NSW coastline is as hot as 27 degrees.

“Big blob of super hot water”: Meder said extreme weather and unusual ocean events, like mass marine die offs, are linked to the increasing marine heat waves along the east coast. 

• For example: warm water in the ocean creates moisture in the atmosphere that results in stronger storms and high rainfall.

• Warm ocean temperatures can lead to algal blooms that can be poisonous to marine life that would ordinarily feed on those algae.

Meder noted there's a “big blob of super hot water” sitting just off NSW's coastline that has been influential in driving strong onshore winds.

• “When weather pushes blue dragons up against the coastline, it suggests something significant is going on in the ocean,” Meder said.

Heatin’ up: As ocean waters get hotter, the East Australian Current (EAC) is getting stronger.

The EAC moves from Queensland through the Great Barrier Reef and is pushing further south to the New South Wales coastline and beyond.

• “This current is just absolutely roaring down the coast toward Tasmania,” Meder said. “There’s a powerful pulse of it sitting offshore right now off our coast.

Why is the ocean getting hotter? Global temperatures are rising due to human-induced climate change. The burning of fossil fuels (coal, oil, and gas) leads to an increase in greenhouse gas emissions. This traps heat in the atmosphere and excess heat is absorbed by the ocean. 

It’s not just blue dragons: Last week, hundreds of thousands of pipis were found washed ashore along South Dunbogan beach at Diamond Head.

A spokesperson for the NSW Department of Primary Industries and Regional Development said the cause of death remains unknown, but noted these mass deaths can be a result of extreme weather, tides, low oxygen events, starvation and infection by a range of pathogens.

• Mass mortalities of moon pipis have previously been reported between South Ballina and Coffs Harbour (2009-2010). 

• Moon pipis are generally found below the low tide mark in the wave break zone.  

Meder said masses of shellfish dying is likely a consequence of the increasingly unusual ocean conditions and marine heat waves.

• “Sometimes we get algal blooms and so on that can be poisonous to the shellfish which would ordinarily be feeding on those algae,” Meder said.

Meder said while he can’t confirm the link between blue dragons and dead pipis washing ashore on the Mid North Coast, he said there is strong evidence the underlying driver of both events would be connected to unstable ocean conditions, like above average ocean temperatures.

• “The ocean is what drives most of the weather that we see and a whole lot of our climate in the bigger sense,” Meder said.

Ocean changing rapidly

Meder said the ocean is changing at such a rapid rate, “the scientific community, fishery managers, and our environment managers are really struggling to keep up with the pace of change”.

• “Scientists were saying 10 years ago all these things could happen in the future if we're not careful. Those things have already happened and we’ve moved onto the next stage,” he said. “The ocean is really changing and moving faster than we can really keep up with as far as managing the impacts on things like shellfish and fisheries.”

“These big, one off, really unusual events that are happening increasingly really show you that our oceans are changing and changing fast.”