Water column stratification, phytoplankton diversity and consequences
for resource use and productivity
| Project acronym: | HYIII-NTNU-24 |
| Name of Group Leader: | Maren Striebel |
| User-Project Title: | Water column stratification, phytoplankton diversity and consequences for resource use and productivity |
| Facility: | Marine Cybernetics Laboratory |
| Proceedings TA Project: | Water column stratification, phytoplankton diversity and consequences for resource use and productivity |
| Data Management Report: | Data Management Reports Page You will need to login to view this page |
User Project Objectives:
We proposed to analyze the un-investigated links between disturbances of water column stratification and diversity and its consequences for marine plankton dynamics in a gradient of disturbances at different nutrient supply rates in a large scale mesocosm experiment. We hypothesized that experimental disturbances of water column stratification will have consequences for phytoplankton diversity and thereby affect the resource use efficiency and carbon production of phytoplankton and phytoplankton – zooplankton interactions.
Our objectives were as follows:
- To analyse the relationship between disturbance of water column stratification and phytoplankton diversity to be able to generalize possible relationships between stratification disturbances and phytoplankton diversity in pelagic environments.
- To analyse the relationship between marine phytoplankton diversity and diversity dependent resource use efficiency, the stability of resource use efficiency and carbon production
- To analyse the relationship between diversity dependent carbon dynamics of phytoplankton and zooplankton growth. We investigated the link between disturbances of the water column, phytoplankton diversity and its consequences for zooplankton growth in a marine pelagic community.
- To analyse the relationship between disturbance and the growth and diversity of ciliates. Our experiments show how rapid changes in the grazer community can influence the impact of disturbance on primary producers.
User-Project Achievements and difficulties encountered
We studied the responses of a natural coastal phytoplankton community to manipulations of the stratified water column. We installed 24 enclosures (10m depth) and disturbed the stratification of the water column by artificially mixing the water column with a Secci-plate with different time intervals (1-16 days). Undisturbed mesocosms (mixed every 32 days) acted as the least disturbed mesocosms in the gradient. We performed the experiments at two nutrient levels, a un-fertilized and a moderate supply level (0.5 μg P l-1 d-1; Si:N:P 16:16:1) compared to the natural loading of the system (Vadstein et al. 2004). We followed the response of phytoplankton, protist (ciliate and flagellate) and zooplankton communities to stratification disturbances for about 4 weeks. We were especially interested in the consequences of stratification disturbances for phytoplankton diversity and thereby phytoplankton resource use efficiency and carbon dynamics
Highlights important research results
At the moment we are still analyzing samples, phytoplankton, ciliates, and zooplankton samples that are very time-consuming. Thus, we hope that we will finish these analyses until the beginning of 2010. Then we will be able to investigate the relationship between disturbance of water column stratification and phytoplankton and ciliate diversity.
Additionally, we just finished the nutrient analysis (C, N, P) and after gaining the phytoplankton and ciliate data we will be able to analyse the relationship between marine phytoplankton diversity and diversity dependent resource use efficiency, the stability of resource use efficiency and carbon production. Moreover, we will analyse the relationship between diversity dependent carbon dynamics of phytoplankton and zooplankton growth and analyse the relationship between disturbance and the growth and diversity of ciliates.
Pictures 1-4: Experimental setup: (1) daily mixing, (2) experimental setup, (3) daily mixing and fertilization, and (4) raft
with enclosures.
Pictures 5-6: Enclosure with bottle for ciliate growth experiments (5) and setup for dialysis experiments to determine
phytoplankton primary production and loss rates (6).
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