Australia Weather News

Sea grass banked up against the Busselton Jetty. - ABC

The world-famous Busselton Jetty has been swamped by tonnes of sea grass that was washed onto the beach of the WA South West holiday town by strong storms last week.

The sea grass is now covering the waterline for metres out to sea, and is posing a smelly problem for the local authorities.

It has channelled into the beach alongside the jetty — the longest timber-plied jetty in the southern hemisphere, which extends for 1.84 kilometres out to sea.

In 2014, the WA Government spent $28 million fixing a problematic groyne that allowed more than 100,000 square metres of rotting sea grass to accumulate on the beach every year.

Busselton resident Margaret Macpherson said she couldn't believe how much seagrass had deposited on the jetty beach.

"I've been here for 28 years and I've never seen it like this," she said.

Another local resident Nola Angus said the recent storm had aggravated the situation.

"I was hoping some of the seaweed would have gone with the storm but unfortunately it's gotten even worse," she said.

Ms Angus said the smell could at times be unbearable.

"It was horrific. At [1:00am] you'd be getting up in the summer time and closing your windows to try and get the smell out," she said.

Sophie Teede, a marine biologist who has worked at the Busselton Jetty for seven years, said she had not seen a washup to this extent for a number of years.

She emphasised that though the mounds of plant matter look like seaweed, it is actually a different type of organism.

"That storm really cleaned out a lot of the dead and detached leaves from the seagrass meadows themselves," she said.

"With all the swell rolling around, that deposits all of those detached leaves up on the beach itself."

The sea grass provides an environment for small marine animals and also helps hold the coastline together to guard against erosion.

"It has a really protective element to protect the sand from eroding away from the beach itself," Ms Teede said.

"I think the way the seagrass has washed up on the beach now has definitely been influenced by the sand bags that have been put out by the City of Busselton.

"There's been a big build up under the jetty, and that has forced a lot of it to where it is now."

Ms Teede said there were no real negative environmental effects of such a large amount of seagrass, which would eventually wash away by itself.

The worst effect was likely to be the smell of the material as it dries in the sun.

The local council, which regularly employs front-end loaders to clear away sea grass from the town's beaches during the peak tourism season in summer, is hoping it may avoid a costly clean-up effort to remove the sea debris.

Busselton Mayor Grant Henley said he was hoping more storms forecast for later this week would wash away much of the seagrass naturally.

"This storm was a little unusual in its duration and the direction it came in, which has lead to this almost unnatural build up," he said.

"Well cut some channels through this so there's access to some of the infrastructure, but we won't be removing large amounts of seagrass

"We'll wait and see what nature does and if it becomes a pressing issue then we'll see what steps we can take."

ABC