Comparison of Fossil Pigments with 20 Years of Phytoplankton Data from Eutrophic Lake 227, Experimental Lakes Area, Ontario

1994 ◽  
Vol 51 (10) ◽  
pp. 2286-2299 ◽  
Author(s):  
P. R. Leavitt ◽  
D. L. Findlay
Keyword(s):  
Standing Crop ◽  
Algal Biomass ◽  
Carbon Fixation ◽  
Eutrophic Lake ◽  
Laminated Sediments ◽  
Experimental Lakes Area ◽  
Pheophytin A ◽  
Fossil Pigments ◽  
Annually Laminated Sediments ◽  
Nitrogen Additions

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. N2-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.

Cladocera Community Response to Experimental Eutrophication in Lake 227 as Recorded in Laminated Sediments

1994 ◽  
Vol 51 (10) ◽  
pp. 2312-2321 ◽  
Author(s):  
Brenda J. Hann ◽  
Peter R. Leavitt ◽  
Philip S. S. Chang
Keyword(s):  
Standing Crop ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Community Response ◽  
Laminated Sediments ◽  
Accumulation Rates ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Annually Laminated Sediments ◽  
Chemical Conditions

The response of pelagic zooplankton to experimental fertilization was compared with the fossil record of Cladocera obtained from the annually laminated sediments of Lake 227, Experimental Lakes Area, northwestern Ontario. Constrained cluster analysis of both total fossil Cladocera and littoral chydorid communities clearly distinguished between pre- and post-eutrophication communities and further differentiated between years of high and low nitrogen:phosphorus fertilization ratios. However, there were few chydorid species extirpations resulting from the manipulation. Total chydorid accumulation rates and indices of species diversity, richness, and equitability were relatively constant over the last century and were not affected by fertilization. Among pelagic Cladocera, Bosmina longirostris abundance declined > 60% after initial fertilization. Although harsh chemical conditions (pH > 10) may have contributed to reduced abundance of pelagic Cladocera, Bosmina populations were also naturally variable prior to manipulation. Changes in Bosmina morphology (mucrone, antennule, and carapace length) and cladoceran size ratios (Daphnia/[Daphnia + Bosmina]) suggested that zooplanktivory by fish and invertebrates exercised important control of herbivore populations. Fossil Bosmina concentration (remains∙[g dry wt]−1 or remains∙[g organic matter]−1) were significantly correlated (r = 0.66, P < 0.01, 1970–1989) to standing crop in the water column (animals∙m−2). Fossil accumulation rate (remains∙cm−2∙yr−1) was not significantly correlated to Bosmina abundance, perhaps because of errors in determining bulk sediment accumulation rates.

Influence of Reservoir Transit on Riverine Algal Transport and Abundance

1984 ◽  
Vol 41 (12) ◽  
pp. 1803-1813 ◽  
Author(s):  
D. M. Søballe ◽  
R. W. Bachmann
Keyword(s):  
Water Temperature ◽  
Retention Time ◽  
Standing Crop ◽  
Algal Biomass ◽  
Chlorophyll Concentration ◽  
Light Limitation ◽  
Des Moines ◽  
Flow Dependence ◽  
Major Loss ◽  
Chlorophyll Concentrations

The Des Moines River lost 65–75% of its algal standing crop (chlorophyll a) in passing through each of two impoundments (mean retention times 11 and 16 d), and chlorophyll concentrations within both impoundments were 50–90% below the predictions of empirical chlorophyll–nutrient models. Sedimentation of river-borne algae and light limitation within the impoundments were identified as major loss processes. A reduction in algal size from upstream to downstream in one reservoir paralleled the loss of algal biomass. Algal losses in each impoundment increased with both increasing retention time and water temperature so that chlorophyll concentration below the dams was uncoupled from the temperature and flow dependence seen in river reaches not influenced by impoundments. The reduction in riverine algal transport associated with reservoir transit was cumulative over the two-reservoir series; this reduction can be interpreted as a "reset" to river headwater conditions.

scholarly journals A 40,000-Year Varve Chronology from Lake Suigetsu, Japan: Extension of the 14C Calibration Curve

Radiocarbon ◽  
1997 ◽  
Vol 40 (1) ◽  
pp. 505-515 ◽  
Author(s):  
Hiroyuki Kitagawa ◽  
Johannes Van Der Plicht
Keyword(s):  
Tree Ring ◽  
Calibration Curve ◽  
Time Scale ◽  
Mass Spectrometric ◽  
Laminated Sediments ◽  
Varve Chronology ◽  
Total Range ◽  
Dating Method ◽  
Annually Laminated Sediments ◽  
Potential Tool

A sequence of annually laminated sediments is a potential tool for calibrating the radiocarbon time scale beyond the range of the absolute tree-ring calibration (11 ka). We performed accelerator mass spectrometric (AMS) 14C measurements on >250 terrestrial macrofossil samples from a 40,000-yr varve sequence from Lake Suigetsu, Japan. The results yield the first calibration curve for the total range of the 14C dating method.

Paleolimnological studies of annually-laminated sediments in Loe Pool, Cornwall, U.K.

1983 ◽  
pp. 185-191 ◽  
Author(s):  
M. A. Coard ◽  
S. M. Cousen ◽  
A. H. Cuttler ◽  
H. J. Dean ◽  
J. A. Dearing ◽  
...  
Keyword(s):  
Laminated Sediments ◽  
Annually Laminated Sediments

Analysis of the Response of Hypolimnetic Phytoplankton in Continuous Culture to Increased Light or Phosphorus Using Track Autoradiography

1980 ◽  
Vol 37 (3) ◽  
pp. 434-441 ◽  
Author(s):  
R. Knoechel ◽  
F. deNoyelles Jr.
Keyword(s):  
Continuous Culture ◽  
Carbon Fixation ◽  
Common Species ◽  
Total Carbon ◽  
Experimental Lakes Area ◽  
Phosphorus Enrichment ◽  
Species Response ◽  
Ankistrodesmus Falcatus ◽  
Wide Range ◽  
Track Autoradiography

Phytoplankton from the hypolimnetic biomass peak in Lake 266SW (Experimental Lakes Area, northwestern Ontario) was subjected to conditions of increased light or phosphorus in continuous culture. Phosphorus enrichment increased total carbon fixation 16% relative to the control; however, the particulate fraction was initially depressed and the phytoplankton biomass was less than 2% greater after 10 d. The high light culture displayed 21% higher final biomass despite a 13% decline in total carbon fixation which was primarily due to reduced extracellular release. The 21 most common species demonstrated a wide range of positive and negative biomass responses to the experimental perturbations; however, the three dominant chrysophyte species all responded positively to higher light. Detection of population biomass changes provided a direct and accurate means of quantifying perturbation effects provided the species response was stable over several days. Measurement of carbon uptake rates of species through track autoradiography provided the additional sensitivity and temporal resolution needed to monitor low level or variable responses. Synedra radians exhibited a lengthy lag period before demonstrating a strong positive response to phosphorus enrichment, while Dinobryon sertularia shifted from neutral to strongly negative and then strongly positive within a 3-d period. These results illustrate the inadequacy of short-term bioassays for the prediction of long-term perturbation effects.Key words: growth rate, primary production, Ankistrodesmus falcatus, Dinobryon sertularia, Synedra radians

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