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<p>This study investigated the effects of air exposure on the physiological and biochemical parameters of the seagrass <i>Halodule wrightii</i> Ascherson in a tropical coastal environment in Brazil. Ecophysiological responses were evaluated through measurements of photosynthetic potential, chlorophyll content, oxidative damage (MDA), hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), electron transport rate (ETR), shoot density, biomass, and leaf morphometry. Sampling was conducted across four distinct levels of leaf burning and air exposure. Results revealed that <i>H. wrightii</i> exhibits photosynthetic acclimation to air exposure by adjusting total chlorophyll content and the chlorophyll a:b ratio under high irradiance, accelerating leaf senescence and reducing aboveground biomass. Notably, MDA and H<sub>2</sub>O<sub>2</sub> levels were unaffected by air exposure. In submerged areas, the seagrass decreased the chlorophyll a:b ratio, indicating an increased need for sunlight capture, which correlates with higher aboveground biomass and lower shoot density. Overall, although seagrasses are plant-adapted to live fully submerged, <i>H. wrightii</i> demonstrated a capacity for temporary air exposure capacity; however, rising temperatures may exceed <i>H. wrightii</i>’s acclimation limits, potentially resulting in significant stress and damage.</p>

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Photosynthetic acclimation of the seagrass Halodule wrightii Asch. in air-exposed meadows

  • 期刊论文

  • 发表日期：

    2025年5月27日

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  • Priscila Fernanda da Silva,
  • José Bonomi-Barufi,
  • Marcus Vinicius Loss Sperandio,
  • Josias Alexandre da Silva Filho,
  • Paulo Antunes Horta Junior,
  • Karine Matos Magalhães

摘要

This study investigated the effects of air exposure on the physiological and biochemical parameters of the seagrass Halodule wrightii Ascherson in a tropical coastal environment in Brazil. Ecophysiological responses were evaluated through measurements of photosynthetic potential, chlorophyll content, oxidative damage (MDA), hydrogen peroxide (H2O2), electron transport rate (ETR), shoot density, biomass, and leaf morphometry. Sampling was conducted across four distinct levels of leaf burning and air exposure. Results revealed that H. wrightii exhibits photosynthetic acclimation to air exposure by adjusting total chlorophyll content and the chlorophyll a:b ratio under high irradiance, accelerating leaf senescence and reducing aboveground biomass. Notably, MDA and H2O2 levels were unaffected by air exposure. In submerged areas, the seagrass decreased the chlorophyll a:b ratio, indicating an increased need for sunlight capture, which correlates with higher aboveground biomass and lower shoot density. Overall, although seagrasses are plant-adapted to live fully submerged, H. wrightii demonstrated a capacity for temporary air exposure capacity; however, rising temperatures may exceed H. wrightii’s acclimation limits, potentially resulting in significant stress and damage.