| title: | Impact of climate change on ecosystems of large shallow lakes, mediated by the altered inflow of substances |
|---|---|
| reg no: | ETF5738 |
| project type: | Estonian Science Foundation research grant |
| subject: |
1.16. Marine Sciences and Limnology |
| status: | accepted |
| institution: | Institute of Zoology and Botany at Estonian University of Life Sciences |
| head of project: | Tiina Nõges |
| duration: | 01.01.2004 - 31.12.2007 |
| description: | Studies on global climate have revealed that the conditions in the Northern Hemisphere tend to change for warmer, winters are becoming wetter and summers drier. These changes are attributed to the increasing content of green-house gases in the atmosphere, which is probably reflected in the increasing tendency of the North Atlantic Oscillation Index (NAO). Climate change affects the balance of heat, water and substances in lake catchments resulting in changes of the hydrological regime and loadings. Hydrological changes have the strongest impact in shallow lakes where they cause big changes in the water volume and lake depth. A basic research is planned to study the influence of the inflow of substances on the ecosystem of large shallow lakes. First of all, the response of phyto- and bacterioplankton will be considered. The role of the dynamics of dissolved organic matter on the underwater light climate will be investigated as well. Work hypotheses: in positive phase of NAO the amount of water discharged into the lakes increases bringing about the elevated inflow of dissolved substances. However, the concentration of phosphorus in lake water tends to be lower in water-rich years. This is caused by the effect of dilution as well as by the less intensive leakage from sediments because of smaller resuspension in deeper lake. The concentration of DOC in lakes is higher in water-rich years. In the deeper lake where the water column is on the average less illuminated than in shallower lake, the increased concentration of DOM weakens the underwater irradiance contributing to the sharpening of phytoplankton light limitation and to the reduction of its biomass. Higher concentration of DOM may favor bacteria while the lower phytoplankton production in DOM-rich years can reduce bacterial biomass if they are dependant on phytoplankton exudates and degradation products. Two Estonian large lakes Võrtsjärv and Peipsi offer an unique opportunity to study the impact of climatic change on the ecosystem of shallow lakes. They are among few lakes in the World, which water level is unregulated and has a natural variability strongly associated to the changes of NAO. More than 30-year long time series from these lakes enable to analyse the impact of climate change on the ecosystems. Monthly data on phytoplankton from L. Võrtsjärv start from the year 1964. Also for L. Peipsi the data stretch back to the 1960s, though having a lower frequency. |
| project group | ||||
|---|---|---|---|---|
| no | name | institution | position | |
| 1. | Helen Agasild | EPMÜ ZBI | vanemlaborant | |
| 2. | Tõnu Feldmann | EPMÜ ZBI | vanemlaborant | |
| 3. | Tiina Nõges | Institute of Zoology and Botany at Estonian University of Life Sciences | senior researcher | |
| 4. | Anu Reinart | Uppsala Ülikool | teadur | |
| 5. | Lea Tuvikene | EPMÜ ZBI | teadur | |
| 6. | Ilmar Tõnno | EPMÜ ZBI | doktorant | |