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Different mixing techniques in experimental mesocosms-does mixing affect plankton biomass and community composition?
Maren Striebel1, Leo Kirchmaier2, Peter Hingsamer3
1WasserCluster Lunz, Dr. Carl Kupelwieser Promenade 5, 3293 Lunz am See, Austria ; Institute of Hydrobiology and Aquatic Ecosystem Management, University of Natural Resources and Life Sciences, Max Emanuel-Strasse 17, 1180 Vienna, Austria.
Limnology and Oceanography, Methods
|March 3, 2015
Summary
Mechanical mixing using a disc in aquatic mesocosms effectively enhanced zooplankton biomass. This method proved superior for studying plankton dynamics in experimental ecosystems.
Area of Science:
- Aquatic Ecology
- Limnology
- Experimental Ecology
Background:
- Mesocosm studies are vital for understanding aquatic ecosystems, particularly trophic interactions and biogeochemical cycling.
- Experimental setup, including water column mixing, significantly influences mesocosm outcomes.
- Artificial enclosures alter natural mixing regimes, necessitating controlled mixing strategies.
Purpose of the Study:
- To evaluate the impact of different water column mixing techniques on plankton communities in outdoor mesocosms.
- To compare the effectiveness of mechanical mixing (disc), airlift systems, and bubbling for simulating natural conditions.
- To assess the influence of mixing on phytoplankton, ciliate, and zooplankton biomass and community composition.
Main Methods:
- Conducted a 19-day outdoor mesocosm experiment.
- Implemented three active mixing techniques: disc, airlift, and bubbling, alongside a non-mixed control.
- Monitored phytoplankton, ciliate, and zooplankton communities throughout the experiment.
Main Results:
- Mechanical mixing with a disc generated an undertow effect, proving most effective.
- Zooplankton biomass was significantly higher in mesocosms mixed with the disc.
- Airlift treatments showed a reduced proportion of small flagellates, but no significant differences in overall phytoplankton or zooplankton community composition were observed across actively mixed treatments.
Conclusions:
- Mechanical mixing via a disc is a highly effective method for enhancing zooplankton biomass in mesocosm studies.
- While mixing affects certain plankton groups, overall community composition differences were minimal across actively mixed treatments.
- The choice of mixing technique should be tailored to the specific biological processes under investigation in aquatic mesocosms.
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