“(There is a) mix of tropical, temperate and WA endemics. With the higher sea temperatures, we expected the proportion of tropical species to increase, but this did not happen on the west side of Rottnest, where all three groups declined substantially,” he said.
“These findings show that even with the high degree of protection from direct human activities, these areas are not immune to the impacts of global climate change.”
The island is promoted as having “some of the most biodiverse marine gardens you could find”, with about 400 species of fish and 20 species of coral calling the island home.
Wells said tackling climate change had to be an urgent priority to ensure the island and other biodiverse hotspots continue to exist in the future.
“This is not a local problem, it’s a global climate change problem,” he said. “Hopefully the reef system can bounce back when conditions improve.”
Marine heat waves have also caused problems in other parts of the state.
All of WA’s coral reefs have bleached at least once since 2010. In 2016, during an El Nino year when there are historically warmer waters, there was a reduction in coral cover and bleaching at northern locations such as Christmas Island, Ashmore, and Scott Reef, as well as on the coast near the Kimberley.
Further south, Ningaloo and Pilbara reefs, seagrass and kelp forests took a beating in 2011, 2021 and 2022 – as the Leeuwin Current intensified and brought warm waters south.
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