Daphnia grazing, the clear water phase, and implications of minerogenic particles in Onondaga Lake

Alternative models for the dynamics of edible phytoplankton were compared using long-term data from mesotrophic Paul Lake and eutrophic Lake Mendota. Alternative models fit to the data contrasted linear versus logistic algal growth, type I versus type II functional response, and prey-dependent versus ratio-dependent predation. In both lakes, the model with lowest prediction error had logistic algal growth and a type I, prey-dependent functional response. Under these models, the spring bloom and clear-water phase of productive lakes can be explained as an incomplete predator–prey cycle: the spring pulse of edible algae is followed by a peak of Zooplankton; then, edible algae are overgrazed leading to the clear-water phase and collapse of the grazer biomass. This study demonstrates the use of time series data at the ecosystem scale to identify process-based models, contrast alternative models on a probabilistic basis, and estimate parameters. This approach avoids the assumptions involved in extrapolating ecosystem models from smaller scale studies.

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Do zooplankton contribute to an ultraviolet clear-water phase in lakes?

Limnology and Oceanography ◽

10.4319/lo.2007.52.2.0662 ◽

2007 ◽

Vol 52 (2) ◽

pp. 662-667 ◽

Cited By ~ 16

Author(s):

Craig E. Williamson ◽

Hendrika J. De Lange ◽

Dina M. Leech

Keyword(s):

Water Phase ◽

Clear Water ◽

Clear Water Phase

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Clear-water phase in the Řimov Reservoir (South Bohemia): Controlling factors

SIL Proceedings 1922-2010 ◽

10.1080/03680770.1989.11898975 ◽

1991 ◽

Vol 24 (2) ◽

pp. 1336-1339

Author(s):

V. Vyhnálek ◽

J. Komárková ◽

J. Seďa ◽

Z. Brandl ◽

K. Šimek ◽

...

Keyword(s):

Controlling Factors ◽

Water Phase ◽

Clear Water ◽

Římov Reservoir ◽

Clear Water Phase ◽

South Bohemia

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Influences of grazing on temporal patterns of algal pigments in suspended and sedimenting algae in a north temperate lake

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f98-153 ◽

1999 ◽

Vol 56 (1) ◽

pp. 60-69 ◽

Cited By ~ 12

Author(s):

David Poister ◽

David E Armstrong ◽

James P Hurley

Keyword(s):

Water Column ◽

Chlorophyll A ◽

Temporal Trends ◽

Sediment Traps ◽

Grazing Pressure ◽

Water Phase ◽

Carotenoid Pigment ◽

Clear Water ◽

Heavy Grazing ◽

Clear Water Phase

The concentrations of phytoplankton pigments in suspended and settling particles were measured in Trout Lake, Wisconsin, U.S.A., during the 1993 ice-free season. A decrease in water column concentrations of chlorophyll a coincident with an increase in pheophorbide and pheophytin concentrations occurred during a "clear-water" phase in June. The lack of a corresponding decrease in carotenoid pigment concentrations indicated that carotenoid pigments were degraded to a lesser extent than chlorophyll a during this period of heavy grazing pressure. Chlorophyll a, pheophorbide, and pheophytin showed temporal trends in fluxes to sediment traps that were similar for all pigments but did not correspond to trends in water column pigment concentration. Fucoxanthin concentrations and microscopic examination indicated that the sedimentation of large, dense diatoms increased the sedimentation rate of chlorophyll during the clear-water phase. In addition, ungrazed diatoms apparently were the main source of pheophorbide in trap material during the clear-water phase, indicating that pheophorbide should not be used as a surrogate for fecal pellet sedimentation in lakes influenced by the sedimentation of large diatoms.

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