Influence of temperature and stratification on spring succession of the plankton community in deep lakes

• Applicant: Professor Dr. Wilfried Gabriel, since 6/2009
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2004 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5430203

A major impact of global warming on European lakes will be mediated through effects on seasonal succession of the plankton. E.g., the timing of the spring clearwater phase (a period of low algal densities caused by intense grazing from Daphnia) is linked to climate, with warmer winters being followed by an earlier onset and a longer duration of the clearwater phase, and an earlier onset of the spring increase and the summer decline of Daphnia. There are two non-exclusive hypotheses by which mild winters might favour an early build-up of Daphnia biomass: (i) enhanced algal production; (ii) increased metabolic rate. Both depend on the seasonal progression of thermal stratification of lakes. We propose two field experiments designed to disentangle the separate impacts of stratification depth, temperature, and nutrient availability on seasonal succession in the plankton. We will also search existing lake data for trends in the seasonal development of these physico-chemical variables that are driven by interannual climate variability. The experiments will run from April to June and cross-classify (i) three mixing depths with two temperatures (ambient/reduced) in presence and absence of a hypolimnion, and (ii) two temporal patterns of seasonal stratification (early/late) with two temperatures (ambient/ reduced) and two nutrient levels (ambient/enhanced). The data search will focus on regularly stratifying, deep lakes for which data are available with high resolution and for greater than 5 years. Our ultimate goal is to link climate variables to key processes in the plankton in order to predict realistic scenarios of climatic forcing of spring and summer succession in the plankton.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1162: The Impact of Climate Variability on Aquatic Ecosystems (AQUASHIFT)
• Participating Person: Professor Dr. Herwig Stibor
• Ehemaliger Antragsteller: Professor Dr. Sebastian Diehl, until 6/2009