Losing cause

8 July 2016

Published in Science: According to an international team led by scientists from the University of Western Australia*, a kelp forest ecosystem became extinct along 100 kilometres of Western Australia’s coastline following a heatwave in 2011.

Extensive underwater forests of Australian kelps were wiped out by extreme temperatures in 2011
image: Thomas Wernberg

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

It revealed the dramatic impact of the heatwave combined with decades of ocean warming.

Illustration of the shif in the tropical and temperate ecosystem boundaries
Credit: Thomas Wernberg

As the temperatures exceeded anything previously experienced by the kelp forests, they collapsed, and there were now signs of recovery found five years later.

Kelp forests are the biological engine of Australia’s Great Southern Reef, where they support globally unique temperate marine biodiversity. With the collapse of the forests, many cool water fishes, seaweeds and invertebrates disappeared and were replaced by reef communities from more typical tropical regions, such as tropical grazing fishes. These now prevent the kelp forests from recovering.

The research demonstrates a climate-driven break-down of long-standing biogeographic boundaries with lasting consequences, and this harbours a warning that many ecosystems man not be resilient to rapid climate change.

As put by Dr Elizabeth Sinclair, a senior research fellow at University of Western Australia's Oceans Institute who did not participate in the study:

"Wernberg et al.'s new research documents an alarming change in another important habitat-forming, marine ecosystem - kelp forests. While the Great Barrier Reef (GBR) has received much recent media exposure in relation to the widespread coral bleaching event this past summer, the impacts of marine heat waves on other marine ecosystems, such as cool water kelps and seagrasses, are just as devastating."

*The study was led by researchers from UWA's Ocean Institute, with collaborators from the CSIRO, AIMS, WA Museum, DPaW, Curtin University, the Australian National University and several international research partners.

Story is based on information provided by the University of Western Australia