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EFFECTS OF ENVIRONMENTAL VARIATION ON SINKING RATES OF MARINE PHYTOPLANKTON 1
Author(s) -
Culver Mary E.,
Smith Walker O.
Publication year - 1989
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1989.tb00122.x
Subject(s) - photic zone , phytoplankton , irradiance , biology , diatom , biogenic silica , chaetoceros , oceanography , total inorganic carbon , water column , chlorophyll a , flux (metallurgy) , carbon cycle , nitrate , pelagic zone , ecology , nutrient , botany , carbon dioxide , ecosystem , chemistry , physics , organic chemistry , quantum mechanics , geology
The effects of environmental variables, particularly irradiance, on the sinking rates of phytoplankton were investigated using cultures of Chaetoceros gracilis Schütt and C. flexuosum Mangin in laboratory experiments; these data were compared with results from assemblages in the open ocean and marginal ice zone of the Greenland Sea. In culture experiments both the irradiance under which the diatom was grown and culture growth rate were positively correlated with sinking rates. Sinking rates (ψ) in the Greenland Sea were smallest when determined from chlorophyll (mean ψ chl = 0.14 m · d −1 ) and biogenic silica (ψ si = 0.14 m · d −1 ) and greatest when determined from particulate carbon (ψ c = 0.55 m · d −1 ) and nitrogen (ψ N = 0.64 m · d −1 ). Field measurements indicated that variations in sinking may be associated with changes in irradiance and nitrate concentrations. Because these factors do not directly affect water density, they must be inducing physiological changes in the cell which affect buoyancy. Although a direct response to a single environmental variable was not always evident, sinking rates were positively correlated with growth rates in the marginal ice zone, further indicating a connection to physiological processes. Estimats of carbon flux at stations with vertically mixed euphotic zones indicated that approximately 30% of the daily primary production sank from the euphotic zone in the form of small particulates. Calculated carbon flux tended to increase with primary productivity.