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The impact of light intensity and daylength on silicate and nitrate competition among marine phytoplankton
Author(s) -
Sommer Ulrich
Publication year - 1994
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.1994.39.7.1680
Subject(s) - phytoplankton , dominance (genetics) , light intensity , competition (biology) , diatom , flagellate , photoperiodism , nitrate , biology , algae , nutrient , oceanography , ecology , environmental science , botany , physics , geology , optics , biochemistry , gene
I tested the extent to which differences in light supply could influence the outcome of nutrient (Si and N) competition between marine phytoplankton. Competition experiments were performed with 11 species of marine phytoplankton at Si: N ratios from 16 to 124 : 1, light intensities from 28 to 225 µ mol quanta m −2 s −1 , and three different daylengths. Thus, light supply was the composite result of two components: photoperiod and intensity. Diatoms were dominant competitors at higher Si: N ratios, nonsiliceous flagellates at lower ones. Light had no impact on the transition from flagellate to diatom dominance along the Si: N gradient. However, species within those groups were separated along the light gradient. Contrary to theoretical expectations, changes in light intensity and changes in daylength led to similar shifts in species dominance. Therefore, it was possible to describe the light climate by the integral parameter “daily light dose.”