Cool kelp not feeling so hot under a warming ocean

Embargoed until: Publicly released: 2024-01-17 11:01

Australia; NSW; VIC; TAS

Image by Benjamin Davies from Pixabay

Cool edge kelp populations may be more susceptible to climate change and ocean warming than previously recognised, according to Aussie researchers who looked at Ecklonaia radiata, a kelp species common to Australia’s south coasts. The team studied the growth and photosynthesis of kelp forests living in temperatures around the 7°C mark, considered ‘cool edge’ populations, and often overlooked as it’s thought that their warm edge counterparts, living in temperatures up to 26°C, are more at risk as ocean temperatures rise. However the team found cool edge kelp is acclimatised to their local temperatures, and their thermal tolerance and favourable conditions for growth are unlikely to be enhanced under forecasted increases in warming. The team also found that elevated CO2, which can help with heat tolerance in some species of sea grass, does not help E. radiata to tolerate rising sea temperatures.

Media release

From: The Royal Society

Cool-edge populations of the kelp Ecklonia radiata under global ocean change: sensitivity to warming but little effect of ocean acidification

Summary: Kelp forests are threatened by ocean warming, and the effects of co-occurring drivers such as CO2 are rarely considered when predicting their performance in a future ocean. In Australia, the kelp Ecklonia radiata forms extensive forests across seawater temperatures of ~ 7 – 26 °C. Cool-edge populations are typically considered more thermally tolerant than their warm-edge counterparts, but this ignores the possibility of local adaptation. Using thermal performance curves constructed under current and future CO2 levels we demonstrate that elevated CO2 is unlikely to offset negative effects of ocean warming on E. radiata and highlight the potential susceptibility of cool-edge populations to ocean warming.

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Journal/
conference: Proceedings of the Royal Society B

Research:Paper

Organisation/s: Institute for Marine and Antarctic Studies (IMAS), CSIRO, Monash University, The University of Western Australia, University of Technology Sydney (UTS)

Funder: The research was funded by an Australian Research Council Discovery Project to CLH, JB, JG and JAR (grant no: DP200101467).

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