Assessing the long-term impacts of climate change on marine assemblages in South Western AustraliaUnderexplored Reefs

Jack Parker¹, Euan Harvey¹, Ben Saunders¹

¹Curtin University, Australia

To address the relative lack of information on the impact of climate change on temperate ecosystems, our study examines the impact of climate change on marine ecosystems in Southwestern Australia (SWA), focusing on shallow and deeper water reefs (30m-70m) using remotely operated vehicles (ROVs). Surveying a large section of the SWA coastline, our research builds on surveys that began in 2006.
We observed an increase and persistence of warm water species throughout the study area in 2023 with changes in species and functional diversity. While the magnitude of change was higher for marine assemblages in the warmer northern regions, cooler-water regions also exhibited significant shifts. From 2006 to 2015, nearly the entire SWA study area underwent substantial changes linked with the 2011 MHW. These trends were also reflected in deeper reefs, where again warm water species were recorded in 2023 in deeper reefs. These shifts, including alterations in species functional groups and key habitat species like Ecklonia radiata, suggest minimal ecological recovery as assemblages continue to stabilize into new configurations under ongoing climate stress. This study highlights the importance of looking at climate change at the regional scale over a long time period. Furthermore, the study highlights that the rapid and potential permanent shifts in the marine assemblages along the south coast of Western Australia also extend to deeper reefs.