Eco-stink if seaweed dwindles

Warmer ocean temperatures could lead to a reduction of stinking seaweed piles on our beaches, according to new WA research, which is great for tourists but not for marine life or beachfront property.

The research paper from Edith Cowan University’s Centre of Marine Ecosystems looked into the “tropicalisation” of Australia’s coastal waters, which could result in the shift of seagrass, seaweed, fish, turtle and dugong populations southward with rising ocean temperatures.

Lead researcher Associate Professor Glenn Hyndes said as herbivorous marine life moved down the coast they were likely to begin foraging on more southern seagrass fields.

“This increased foraging could decimate those local species meaning there’s nothing washing up on our beaches,” he said.

“That might sound like it’s good news — especially if you live near one of those beaches where seagrass wash up regularly, also known as ‘wrack’.

“But it would have disastrous consequences for the coastal ecosystems in those areas which rely on the nutrients and habitat provided by the wrack to survive.”

Professor Hyndes said the changes predicted for WA were happening more rapidly than elsewhere in the world, and even sooner for the Mid West.

“The movement of herbivores ... will affect seagrasses in the Mid West in the same way that it will further south, but sooner,” he said.

“If seagrass grazers become a prominent feature of the Mid West, they are predicted to graze on seagrass and potentially reduce the amount of seagrass that could be transported into beaches in the region.”

Northern Agricultural Catchment Council coastal and marine program co-ordinator Mic Payne said large swathes of the west coast’s seaweed had already died because of climate change, and the potential loss of the seagrass as well was extremely concerning.

“The positives of losing beach wrack are visual, but seagrass is an incredibly important biological community for our recreational and commercial species,” she said.

“The top of that list would be rock lobster.

“There’s a lot of important (fish) species that recruit and grow up in seagrass bed nurseries ... recreational species like whiting, herring and cobbler could be seriously affected.”

Dr Payne also said the change would not help Geraldton’s erosion woes either, with the beach wrack (which varied in composition seasonally, but could be up to 100 per cent sea grass) potentially acting as a barrier during storm events.

As far as fixing the problem goes, Dr Payne said decisions to ameliorate the situation were entirely political.

“We need some top-level decisions to limit carbon emissions ... even once we make those decisions there’s going to be some lag on the effects,” he said.

“But as things are, the ongoing impact on aquatic communities is going to be quite substantial.”