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Fossil pigments from annually laminated sediments were calibrated with coeval phytoplankton data (1970–1989) from experimentally eutrophied Lake 227 in the Experimental Lakes Area, Ontario. Concentrations of ubiquitous pigments (β-carotene, pheophytin a) were correlated to total algal biomass standing crop (r = 0.56–0.65; P < 0.01) during the ice-free seasons, but not to carbon fixation or water-column chlorophyll (Chl). Indicator pigments were correlated to ice-free season algal biomass for cyanobacteria (echinenone, aphanizophyll) and chlorophytes (lutein–zeaxanthin, pheophytin b)(r = 0.53–0.55, P < 0.05), weakly correlated for cryptophytes (alloxanthin, α-carotene; r = 0.32–0.40, P < 0.10), but were uncorrelated for chrysophytes and diatoms (fucoxanthin, Chl c) or dinoflagellates (peredinin). Premanipulation concentrations of fossil pigments (nmol pigment∙(g organic matter) −1 ) from green algae and filamentous cyanobacteria (myxoxanthophyll) increased 4- to 10-fold in response to eutrophication of Lake 227. N 2 -fixing cyanobacteria (recorded as aphanizophyll) replaced chlorophytes after the nitrogen additions decreased threefold in 1975. In contrast, accumulation rates of pigments (nmol pigment∙rrr −2 ∙yr −1 ) were rarely correlated with algal standing crop or production and were less satisfactory than fossil concentrations for the purpose of detecting changes in phytoplankton community composition.
Leavitt et al. (Sat,) studied this question.