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Optical properties of benthic photosynthetic communities: Fiber‐optic studies of cyanobacterial mats
Author(s) -
Jørgensen Bo Barker,
Des Marais David J.
Publication year - 1988
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1988.33.1.0099
Subject(s) - irradiance , benthic zone , photosynthesis , radiance , chlorophyll a , bacteriochlorophyll , environmental science , phycocyanin , microbial mat , geology , botany , oceanography , optics , cyanobacteria , remote sensing , biology , physics , paleontology , bacteria
A fiber‐optic microprobe was used to analyze the spectral light gradients in benthic cyanobacterial mats with 50‐ µ m depth resolution and 10‐nm spectral resolution. Microcoleus chthonoplastes mats were collected from hypersaline, coastal ponds at Guerrero Negro, Baja California. Gradients of spectral radiance, L , were measured at different angles through the mats and the spherically integrated scalar irradiance, E o , was calculated. Maximal spectral light attenuation was found at the absorption peaks for the dominant photosynthetic pigments: chlorophyll a at 430 and 670 nm, carotenoids at 450–500 nm, phycocyanin at 620 nm, and bacteriochlorophyll a at 800–900 nm. Scattered light had a marked spectral effect on the scalar irradiance which near the mat surface reached up to 190% of the incident irradiance. The spherically integrated irradiance thus differed strongly from the incident irradiance both in total intensity and in spectral composition. These basic optical properties are important for the understanding of photosynthesis and light harvesting in benthic and epiphytic communities.