Inter-Research
Marine Ecology Progress Series

ABSTRACT: During the spring of 1996, phytoplankton samples were collected along a transect from South Wolf Island (Labrador) to Cape Desolation (Greenland). Dense blooms of diatoms were found over the shelf near the coast of Labrador, whereas high concentrations of the colony-forming prymnesiophyte Phaeocystis pouchetii were found close to Greenland. Phytoplankton samples were separated into 2 major groups (diatoms or prymnesiophytes) on the basis of chlorophyll (chl) chl c3/chl a ratios (determined by HPLC analysis), and the effects of species composition on the absorption and photosynthetic characteristics of these 2 high-latitude phytoplankton populations were studied. At all pigment concentrations and all wavelengths examined (apart from 623 nm), the diatom population had a much lower absorption coefficient than the prymnesiophyte population; this was attributed to an increased pigment-packaging effect in the larger diatom cells. Varying proportions of photoprotective pigments also influenced the absorption characteristics of these populations. The low specific-absorption coefficient of the diatom population resulted in a higher maximum photosynthetic quantum yield relative to that of the prymnesiophyte population. The initial slope of the photosynthesis-irradiance (P E) curve (aB) also appeared to be taxon-specific, with higher aB values being recorded for the smaller prymnesiophytes than for the larger diatom cells. The implications of species-dependent variations in phytoplankton absorption coefficients for the retrieval of remotely-sensed chl a are discussed.

KEY WORDS: Phytoplankton absorption · Bio-optical characteristics · Photosynthesis-irradiance curve · High latitudes · HPLC pigments

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Published in MEPS Vol. 201 (2000) on August 9
Print ISSN: 0171-8630; Online ISSN: 1616-1599. Copyright © Inter-Research, Oldendorf/Luhe, 2000