Photosynthetic efficiency and capacity of intertidal temperate seagrass Zostera marina from Rimouski, QC, Canada, under a light intensity gradient

Eelgrass shoots (Zostera marina) from Rimouski, QC, were exposed in July 2020 to a natural gradient of light intensity, ranging from 6 to 860 µmol photons/m²/s, to assess the species' capacity to respond to light attenuation. After 5 and 25 days of light exposure, photosynthetic responses were examined using PAM (Pulse Amplitude Modulated) fluorometry. Rapid Light Curves (RLC) were carried out on the second leaf of each shoot and were used for extraction of photosynthetic parameters, such as the photosynthetic efficiency (alpha), the photosynthetic capacity (ETRmax), and the onset of light saturation of the photosynthetic apparatus (Ek).