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A team of marine scientists led by The University of Western Australia have uncovered the extinction of a kelp forest ecosystem along 100 kilometres of Western Australia’s coastline, following a heatwave that occurred in 2011.

Kelp forests in Western Australia have not experienced a heatwave of this significance before and UWA Associate Professor and lead author Thomas Wernberg from UWA’s Oceans Institute and School of Plant Biology said there were no signs of recovery five years later.

“Temperatures exceeded anything previously experienced by these kelp forests and they collapsed, allowing turf algae, tropical and subtropical fish, seaweed and coral to increase rapidly,” Professor Wernberg said.

“The research analysed data collected between 2001 and 2015 along 2,000 kilometres of the Western Australian coastline.

“It shows how the heatwave combined with decades of ocean warming has broken down long-standing biogeographic boundaries with lasting consequences.”

Professor Wernberg said like trees in a forest or corals on a coral reef, the kelp forests were the foundations of the ecosystem.

“Kelp forests, are the biological engine of Australia’s Great Southern Reef, where they support globally unique temperate marine biodiversity, some of the most valuable fisheries in Australia and reef-related tourism worth over $10 billion per year,” he said.

“Five years after the heatwave, many cool water fishes, seaweeds and invertebrates have disappeared and been replaced by reef communities from more typical tropical regions.”

Dr Scott Bennett, Research Fellow at the Spanish Research Council and co-lead author of the paper said that tropical grazing fishes had increased substantially in abundance and now prevented kelp forests from recovering.

“The impact has been particularly prominent at northern reefs, where kelp forests have disappeared completely,” he said.

“Recovery is unlikely because of the large grazing pressure, continued warming and the likelihood of more heatwaves in the future.”

The extensive loss of kelp forests in Western Australia provides a strong warning of what the future might be like for Australia’s temperate marine environment and the many values it provide to Australians.

The study involved collaboration among CSIRO, AIMS, WA Museum, DPaW, Curtin University, The Australian National University and several international research partners.

A full report of the research can be accessed here

Media references

Jess Reid (A/UWA Media and Public Relations Manager)                         (+61 8) 6488 6876 (+61 4) 13 105 200