Five women of the University of New South Wales (UNSW) are studying crayweed (scientific name Phyllospora comosa) after it has been non-existent along 70km of Sydney coastline.

They are on a mission to choose the optimum population of crayweed to restore it back in Sydney, Eden has been the first stop.

“Everyone has told us how special Eden is, but we are here because we are looking along at a latitudinal gradient. We are looking at different stresses on the crayweed,” PhD student George Wood said.

“We have been measuring things like the photosynthesis of the seaweed, the biomass and the size, whether they are healthy or unhealthy, how much they have been eaten, how many bite marks they have,” Sophie Voerman said.

Eden is the southern most point they will be researching on the mainland, Victoria has been excluded but Tasmania is on their list for the following week where crayweed canopies can reach up to three meters tall.

“We have already looked at fine scale genetic structure around Sydney and didn't find much difference, so this is the next step to start looking at a wider scale,” Ms Wood said.

They are halfway through the three year project, and halfway through their survey – their next site to visit will be Batemans Bay.

Eden has been an exciting location for the researchers as it is the home of the highest variation of seaweed species in the world.

“This little corner of the South East Australian coast has the highest biodiversity and endemism in the world,” Ms Voerman said.

The group snorkeled at Cocora beach, after taking samples they felt the need to stay in the water to enjoy the sights.

“We were surprised by the larger canopies down here – it was like a forest which was really nice to see,” Ms Wood said.

The team are surveying the population genetics of crayweed and how it may be used to aid and assess the success of the crayweed restoration project.

“We are looking at the population genetics, how diverse different communities are because obviously if you are inbred it’s bad and if you aren’t adapted to certain environments, its bad also,” Ms Wood said.

So far the group have looked at the seaweeds past existence in Sydney, restoring it as closely as they can. 

“We have done ten sites, although haven't been successful at all of them.”

“The most recent successful site was at Bondi, after about three or four months the crayweed will start to reproduce, so we are waiting to see if we have been successful at another five sites,” Ms Wood said.

Crayweed provides food and habitat to a huge diversity of marine life, including economically important abalone and crayfish. 

Eden is blessed with an abundance of crayfish and abalone compared to Sydney, the team of crayweed enthusiasts are determined to bring back biodiversity to the waters of Sydney.

“It [crayweed] is everywhere down here, it is one of the dominant canopy former's and habitat former's on the East Australian Coast,” Ms Wood said.

“We want to bring back to Sydney; the epifauna, crayfish and abalone and different microbial communities that are associated with it – which is good for itself but also different pharmaceuticals, a lot of drugs are made from using seaweed.”

It is unknown as to why crayweed had disappeared from the 70km stretch, although there are speculations that sewage and bad water quality may have been the cause.

“It is such an unusual thing for such a long distance of the coast to just disappear,” Ms Wood said.

“No one knows exactly why it has disappeared because it wasn't reported missing until 2008. It went missing probably during the 70’s or 80’s.

“We have based this species on other brown seaweeds that’s really sensitive to excess nutrients and sewage,” Ms Wood said.

“We used to have all of these raw sewage outfalls in Sydney, so the hypothesis is that the water quality was really bad because of the sewage, and now that we have deep water outfalls the quality is much better.”

The team have transported crayweed to sites around Sydney and have been successful, which has indicated the water quality has improved.

For more information on ‘Operation Crayweed’ visit their website.