The Butterfly Effect - How the loss of crayweed could upset the Australian Seafood Industry

The Butterfly Effect - How the loss of crayweed could upset the Australian Seafood Industry

It is often said that a butterfly flapping its wings on one side of the planet can have cataclysmic impacts on places thousands of miles away.  Long before The Butterfly Effect was a 2004 sci-fi film, it was the premise of a meteorologist Edward Lorenz who showed that even the slightest alteration to an environment could echo through time to eventually cause chaos.

This same theory can be applied to ecosystems in our waterways. Take for example crayweed. It is a fairly common kind of kelp, or underwater ‘tree’ that forms forests in the shallows off south eastern Australia.

For the most part, it is about a metre tall, although in Tassie, it can reach heights of 3 metres. The  average person might look at it and shrug.



Surely this visually unremarkable seaweed wouldn’t be too significant a loss?

Well, in the 1980s, Sydney all but lost its population of crayweed. It turns out that it is highly susceptible to changes in water quality, and when sewerage was dumped just on our coastal beaches and reefs, (as well as being pretty unhealthy for swimmers) populations of crayweed began to recede.

The butterfly’s wings flapped.

And as per Lorenz’s model, the reverberations began to make themselves known, and they weren’t good.  As the crayweed vanished, so too did the various animal life that had called it home.

Dr. Ezequiel ‘Ziggy’ Marzinelli from USYD and the Sydney Institute of Marine Science leads up the research side of Operation Crayweed, an official OneFishTwoFish partner, and he joined us to explain the effects of losing crayweed altogether.  “Imagine losing all of the eucalypts and replacing it with short little bushes,” says Ziggy. “They just don’t offer the same benefits that come with crayweed.

The first thing to happen would be that you would lose the habitat for the little things at the bottom of the food chain. The knock on impacts are that some bigger species rely on them for food. Eventually, it can lead to a loss of commercially viable seafoods like abalone and lobster that love hanging out within crayweed forests.”

According to Ziggy, these two species combined are amongst the most economically significant fisheries in the Australian seafood industry, with abalone fetching over $100 a kilo. 

The reverberations of the butterfly’s wings were beginning to be felt. If this had continued, Lorenz’s model shows that the flow on effects can be exponential. An entire industry might have failed, thousands of people could have been out of work. How far this could go is anyone’s guess.

The frightening thing is that this could have happened, were it not for a few important decisions.

“In the late 80s, there were many protests about the water quality,” explains Ziggy. This was more likely due to residents not wishing to swim in untreated sewage, but it turned out to be serendipitously helpful for crayweed along the Sydney coastline as well.

“In the early 1990s, the government decommissioned those nearshore outfalls. They replaced them with deep-water outfalls and improved the treatment of the sewerage  which is now deposited in much deeper water.”

When researchers began to realise the importance of crayweed and the degree to which it had declined off the Sydney shoreline, the next step was to replant populations in key sites along the coast. They began transplanting healthy fertile adult plants from existing populations and attaching them to deforested rocks. Once these were fastened in place using mesh, the plants began to reproduce and  spread.



Now, they find offspring from these transplants hundreds of metres away from the original plant. The second key event that took place to salvage populations of abalone and lobsters was the creation of organisations like Operation Crayweed in order to scale-up the restoration of crayweed forests along the entire coastline of Sydney.

“We know that if you go to places where crayweed never declined, the numbers of abalone are much higher,” says Ziggy. 

The goal is that the Sydney coastline would eventually look no different to these sites.

OneFishTwoFish is proud to partner with Operation Crayweed in this goal, creating an ocean that is as sustainable as possible.

Images courtesy of Operation Crayweed.
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