| title: | Nutrient limitation and the vertical flux of organic matter in the plankton |
|---|---|
| reg no: | ETF5262 |
| project type: | Estonian Science Foundation research grant |
| subject: |
1.16. Marine Sciences and Limnology |
| status: | completed |
| institution: | University of Tartu |
| head of project: | Kalle Olli |
| duration: | 01.01.2002 - 31.12.2004 |
| description: | Nutrient limitation is a central concept in the eutrophication process of surface waters. Different species of plankton organisms and whole communities respond differently to various degrees of the limitation. The possible scenarios how organisms respond to decreased nutrient availability could involve increase of sedimentation losses. Through sedimentation the plankton organisms leave their natural habitat - the productive layer of the water column. This apparent paradox could be understood, if we acknowledge that the survival of the population can be more likely than the dark and cold bottom layers as compared to the impoverished surface. The sedimentation of plankton and detritus is a key process in the biogeochemical processes of the Earth. This is the process which segregates carbon dioxide from the atmosphere and sinks it to the deep ocean for geological time periods. Factors regulating the vertical flux are poorly known, the available models are empirical, imprecise, and depend on questionable assumptions. This proposal intends to experimentally study the linkage of nutrient limitation with the vertical flux of organic matter in the plankton. The proposal has two focal points: nutrient limitation and the regulation of vertical flux of the organic matter. Both of these require a project in their own right, but the joint focus here is based on the hypothesis: 1) nutrient limitation leads to changes in the community composition of phytoplankton; 2) decline of the growth conditions will lead to the death of some species. Their remains contribute to the sinking phytodetritus, increasing the vertical flux. The following oligotrophication will lead to a subsequent decrease in the vertical flux. 3) The deficiency of resources will lead to re-structuation of the planktonic community and the food web to minimize the sedimentation losses of valuable resources; 4) Some species respond to nutrient limitation through formation of resting stages, which sing fast and increase the vertical flux. Falsification or supporting the above hypothesis will be the main scientific contribution of this proposal. |
| project group | ||||
|---|---|---|---|---|
| no | name | institution | position | |
| 1. | Kalle Olli | Tartu University, Institute of Botany and Ecology | Researcher | |