Canopy-forming macroalgae can adapt to marine heatwaves

Area of Science:

• Marine Biology
• Climate Change Ecology
• Conservation Science

Background:

• Seawater warming and marine heatwaves (MHWs) drive coastal habitat loss.
• Assessing marine species' resilience to ocean warming is crucial for conservation and predicting future changes.
• Gongolaria barbata is a key canopy-forming species in the Mediterranean Sea.

Purpose of the Study:

• To investigate the physiological effects of short-term versus long-term MHWs at different timings on Gongolaria barbata recruits.
• To determine the acclimation capacity and tolerance of G. barbata to thermal stress.
• To inform conservation and restoration strategies for marine coastal habitats under climate change.

Main Methods:

• A controlled thermo-tolerance experiment was performed on G. barbata recruits collected from a Mediterranean Marine Protected Area.
• Key physiological variables measured included recruit length, maximal photochemical efficiency of photosystem II (Fv/Fm), photosynthetic pigments, antioxidant compounds, and total antioxidant activity (DPPH).
• Univariate asymmetrical analyses were used to assess the impact of thermal stress duration and timing on physiological responses.

Main Results:

• All measured physiological variables, except recruit length, were significantly affected by the duration and timing of thermal stress.
• Recruits exposed to long-term stress showed higher Fv/Fm ratios, increased chlorophyll and carotenoid content, and higher antioxidant concentrations, suggesting physiological acclimation.
• The observed acclimation mechanisms did not negatively impact the natural growth rate of G. barbata recruits.

Conclusions:

• Gongolaria barbata exhibits physiological acclimation to thermal stress, indicating a higher capacity to adapt to future climate conditions, including MHWs.
• The findings support the hypothesis that marine species' adaptation to thermal stress is more common than anticipated.
• This research provides critical evidence for developing targeted conservation and restoration strategies for vulnerable marine coastal habitats.