The impact of year-to-year changes in the weather on the dynamics of Daphnia in a thermally stratified lake

George, D. G.; Hewitt, D. P.. 2006 The impact of year-to-year changes in the weather on the dynamics of Daphnia in a thermally stratified lake. Aquatic Ecology, 40 (1). 33-47.

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The factors influencing the seasonal dynamics of Daphnia in a thermally stratified lake (Esthwaite Water) are described and related to long-term changes in the weather. The Daphnia produced three cohorts in the year and the strength of the cohorts was determined by year-to-year variations in the physical characteristics of the lake and the abundance of edible algae. Food was most abundant in early summer when small, fast-growing flagellates were particularly common. In late summer, the phytoplankton community was dominated by large, inedible species but edible forms re-appeared when nutrients were entrained by wind mixing. Examples are presented to demonstrate the effect that year-to-year variations in the weather have on the growth of the phytoplankton and the dynamics of the Daphnia. In ‘good’ years, when the lake stratifies early and there are periods of episodic mixing in summer, there are two ‘pulses’ of edible algae and two strong cohorts of Daphnia. In ‘bad’ years when stratification is delayed and there is little episodic mixing, the growth of the edible algae is suppressed and the Daphnia produce two weak cohorts. The results are discussed in relation to the impact of intermediate disturbances on growth of phytoplankton and current theories of population regulation in Daphnia. The evidence suggests that the dynamics of the Daphnia in the lake are strongly influenced by seasonal variations in the mixing regime, the recycling of nutrients and the episodic growth of edible algae

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Other
UKCEH and CEH Sections/Science Areas: _ Ecosystem Assessment & Forecasting
ISSN: 1386-2588
Format Availability: Electronic, Print
Additional Information. Not used in RCUK Gateway to Research.: The original publication is available at
Additional Keywords: Daphnia dynamics, Edible algae, Wind mixing
NORA Subject Terms: Meteorology and Climatology
Ecology and Environment
Date made live: 04 Jul 2007 08:35 +0 (UTC)

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