Antarctic intertidal macroalgae under predicted increased temperatures mediated by global climate change: Would they...

Area of Science:

• Marine Biology
• Climate Change Ecology
• Phycology

Background:

• The Antarctic Peninsula faces significant sea surface temperature (SST) increases due to global climate change.
• Polar seaweeds' responses to elevated SSTs are not well understood, impacting marine biodiversity.
• Potential adaptation mechanisms include the glutathione-ascorbate cycle and heat shock proteins (HSPs).

Purpose of the Study:

• To investigate the ecophysiological and molecular responses of Antarctic intertidal macroalgae to simulated climate change conditions.
• To assess the role of antioxidant systems and HSPs in thermal stress tolerance in polar seaweeds.

Main Methods:

• Exposure of three macroalgae species (Monostroma hariotii, Adenocystis utricularis, Pyropia endiviifolia) to control (2°C) and elevated (8°C) temperatures for 5 days.
• Measurement of photosynthetic activity, photoinhibition, and photoprotection.
• Analysis of hydrogen peroxide (H2O2) production, lipid peroxidation, and levels of glutathione and ascorbate.
• Gene expression analysis of antioxidant enzymes and HSPs in Pyropia endiviifolia.

Main Results:

• No negative ecophysiological effects on photosynthesis or photoprotection were observed at elevated temperatures.
• Moderate increases in H2O2 production and lipid peroxidation were accompanied by stable, reduced glutathione and ascorbate pools.
• Pyropia endiviifolia showed upregulation of antioxidant enzyme and HSP genes under warmer conditions.

Conclusions:

• Antarctic intertidal macroalgae possess robust mechanisms, including the glutathione-ascorbate cycle and HSP induction, to withstand future SST increases.
• These adaptations suggest potential shifts in the latitudinal distribution and thermal tolerance range of polar seaweeds.
• This study provides critical insights into seaweed resilience in a rapidly warming polar environment.