Pr. Leavitt et Dl. Findlay, COMPARISON OF FOSSIL PIGMENTS WITH 20 YEARS OF PHYTOPLANKTON DATA FROM EUTROPHIC LAKE-227, EXPERIMENTAL LAKES AREA, ONTARIO, Canadian journal of fisheries and aquatic sciences, 51(10), 1994, pp. 2286-2299
Fossil pigments from annually laminated sediments were calibrated with
coeval phytoplankton data (1970-1989) from experimentally eutrophied
Fake 227 in the Experimental Lakes Area, Ontario. Concentrations of ub
iquitous pigments (beta-carotene, pheophytin a) were correlated to tot
al algal biomass standing crop (r = 0.56-0.65; P < 0.01) during the ic
e-free seasons, but not to carbon fixation or water-column chlorophyll
(Chi). Indicator pigments were correlated to ice-free season algal bi
omass for cyanobacteria (echinenone, aphanizophyll) and chlorophytes (
lutein-zeaxanthin, pheophytin b)(r = 0.53-0.55, P < 0.05), weakly corr
elated for cryptophytes (alloxanthin, alpha-carotene; r = 0.32-0.40, P
< 0.10), but were uncorrelated for chrysophytes and diatoms (fucoxant
hin, Chl c) or dinoflagellates (peredinin). Premanipulation concentrat
ions of fossil pigments (nmol pigment .(g organic matter)(-1)) from gr
een algae and filamentous cyanobacteria (myxoxanthophyll) increased 4-
to 10-fold in response to eutrophication of Lake 227. N-2-fixing cyan
obacteria (recorded as aphanizophyll) replaced chlorophytes after the
nitrogen additions decreased threefold in 1975. In contrast, accumulat
ion rates of pigments (nmol pigment . m(-2) . yr(-1)) were rarely corr
elated with algal standing crop or production and were less satisfacto
ry than fossil concentrations for the purpose of detecting changes in
phytoplankton community composition.