Light absorption by phytoplankton: development of a matching parameter for algal photosynthesis under different spectral regimes

• Published in: Journal of Plankton Research
• Main Authors: Markager, Stiig, Vincent, Warwick F.
• Format: Text
• Language: English
• Published: Oxford University Press 2001
• Subjects: ORIGINAL ARTICLES; Arctic; Canada; Phytoplankton
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/23/12/1373; https://doi.org/10.1093/plankt/23.12.1373

A spectral matching parameter (absorption efficiency, A e ) was developed to quantify the relationship between the light absorption spectra of phytoplankton communities and the spectral irradiance of their ambient light field. A e was defined as the ratio between the amount of radiation absorbed by the phytoplankton in situ and the amount absorbed in a spectrally flat light regime. This approach was applied to our measurements of spectral absorption for the phytoplankton communities in six lakes in High Arctic Canada that spanned a range of bio-optical conditions. A e values were calculated for the light spectrum down through the water column and for 11 types of artificial light source. Spectral matching varied among lakes and with depth. There was a significant linear relationship between the relative change in A e with depth and the diffuse attenuation coefficient K d (r2 = 0.52, P = 0.012 for K d for the 400–700 nm waveband; r2 = 0.78, P = 0.0003 for K d at 440 nm). The tabulated values for the matching parameter A e allow the comparison of photosynthesis versus irradiance (P versus E) curves among studies using different light sources. A e estimates also facilitate the evaluation of chromatic adaptation in natural waters, and the calculation of spectrally adjusted, in situ primary production down through a water column from P versus E relationships under a single spectral regime.