Impact of top down and bottom up controls on the microbial loop in Turkish shallow lakes : space for time substitute, monitoring and mesocosm approaches

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2012
Özen, Arda
Bacteria, nanoflagellates and ciliates constitute the microbial loop and it is a model of the pathways of carbon and nutrient cycling through microbial components of pelagic aquatic communities. The current study comprised of a comparative study of the microbial food web community along north to south latitudinal gradient using space for time susbtitute, monitoring and mesocosms experiments with contrasting nutrient and predation states. We investigated effect of fish predation through different zooplankton taxa on microbial loop community with in situ food web experiments in 14 lakes along north to south latitudinal gradient. The effect of seasonality was also determined by monitoring in Lakes Eymir and Mogan between 2010 and 2011. Effects of hydrology and fish through microbial community was studied in mesocosms in Lake Eymir. An implication of global warming along with eutrophication on microbial community was further explored in warmed and nutrient enriched artificial ponds during 4 months in Silkeborg, Denmark. Our results revealed that temperature, hydrology, fish, macrophytes and seasonality affected the top down control of zooplankton and bottom up control of nutrients on microbial loop and interactions between controls and increase in these controls had a strong negative impact on the contribution and biomass of microbial loop and change the interactions within microbial community. Global warming may also effect the impact of top down and bottom up controls through increasing eutrophication, temperature, change in hydrology and zooplankton composition and in a consequence of that efficiency of microbial loop may decrease in the future warmer, drier and eutrophic conditions.

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Citation Formats
A. Özen, “Impact of top down and bottom up controls on the microbial loop in Turkish shallow lakes : space for time substitute, monitoring and mesocosm approaches,” Ph.D. - Doctoral Program, Middle East Technical University, 2012.