Light absorption 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 25 days of light exposure, the fraction of incident visible light absorbed by the leaves (absorptance) was quantified with a Lambda850 (PerkinElmer, USA) spectrophotometer with integrating sphere. Light absorption by the photosynthetic components of the leaves (photosynthetic absorptance) was distinguished from the total absorptance by correcting for the non-photosynthetic absorptance at 750 nm (Cummings and Zimmerman, 2003).