We have been invited by Prof. Steve Smith, Director of the National Marine Science Centre at Coffs Harbour to co-ordinate a hub for a Sea Slug Census along our coast. Here's what he said on ABC News today: Scientists watching southerly migration of tropical sea slugs to chart climate change ABC Coffs Coast By Helen Merkell Posted about an hour ago

Blue and yellow Hypselodoris bennetti sea slugs mating, near Muttonbird Island, Coffs Harbour.

The National Marine Science Centre at Coffs Harbour is looking at whether the southerly migration of tropical sea slugs is an indicator of climate change.

According to researchers, south-east Australia is a recognised global climate hotspot and southward shifts in distribution have already been documented for several species.

Evidence suggests more tropical species heading south

Centre director Professor Steve Smith said colourful sea slugs were now being found up to 1,300 kilometres south of their known range.

"We're very confident about that because these are such colourful organisms that they're always seen by divers if they're around," he said. "We know there's been a documented increase in global seawater temperatures [and] we're seeing changes in oceanographic conditions in different parts of the world.

"We know there are predictions for major changes in this part of the world.

"Certainly the evidence at the moment is suggesting that we are getting more tropical species moving further south."

Multi-coloured Miamira magnifica sea slug on the reef off Woolgoolga, north of Coffs Harbour NSW.

Professor Smith said researchers are concerned about whether or not the species in the receiving waters were able to cope with these "invaders".

"At the moment we don't really know what the ecological consequences are," he said.

"We do know high water temperatures can encourage rapid spread of introduced species [and] we've got a classic example with sea slugs.

"In three years, they have spread from central Queensland all the way around to Adelaide."

Professor Smith said migration of sea slugs was not necessarily the 'canary in the coal mine' but was an indicator of warming ocean temperatures.

"Sea slugs are one of the most popular marine invertebrates among divers and rock pool ramblers," he said.

"Because they have this capacity to be very useful indicators of environmental condition, we're currently putting together a program which works with volunteers to document the distribution of these species.

"So, we can use them as a monitoring tool for climate change and any other environmental change."

Sea Slug Census harnessing citizen scientists

The Sea Slug Census, which started in Port Stephens, is now running in three centres after Sydney and the Gold Coast joined up.

"We plan to include the South Coast of NSW sometime in March," Professor Smith said.

"Then we want to extend it across the country to include WA, SA and Victoria with the long-term goal to have an international program.

"It's incredibly popular with underwater photographers and we use all of that information to document the distribution of the species — there's a huge variety of them. "The largest [sea slugs] can be up to 50 centimetres, possibly even bigger. The big Spanish Dancer we get off Coffs Harbour.

"The smallest are so small it's frustrating. You know they're there but you can't see them, so just a few millimetres in size.

"Some are highly cryptic, coloured the same as the habitat they live in [and] then you've got the flamboyant ones that are so popular."

A white with red spots sea slug Goniobranchus splendidus taken at Nelson Bay, NSW.