Hydrobiologia

, Volume 740, Issue 1, pp 25–35

Water level and fish-mediated cascading effects on the microbial community in eutrophic warm shallow lakes: a mesocosm experiment

  • Arda Özen
  • Tuba Bucak
  • Ülkü Nihan Tavşanoğlu
  • Ayşe İdil Çakıroğlu
  • Eti Ester Levi
  • Jan Coppens
  • Erik Jeppesen
  • Meryem Beklioğlu
Primary Research Paper

DOI: 10.1007/s10750-014-1934-1

Cite this article as:
Özen, A., Bucak, T., Tavşanoğlu, Ü.N. et al. Hydrobiologia (2014) 740: 25. doi:10.1007/s10750-014-1934-1

Abstract

Information on the effects of water level changes on microbial planktonic communities in lakes is limited but vital for understanding ecosystem dynamics in Mediterranean lakes subjected to major intra- and inter-annual variations in water level. We performed an in situ mesocosm experiment in an eutrophic Turkish lake at two different depths crossed with presence/absence of fish in order to explore the effects of water level variations and the role of top-down regulation at contrasting depths. Strong effects of fish were found on zooplankton, weakening through the food chain to ciliates, HNF and bacterioplankton, whereas the effect of water level variations was overall modest. Presence of fish resulted in lower biomass of zooplankton and higher biomasses of phytoplankton, ciliates and total plankton. The cascading effects of fish were strongest in the shallow mesocosms as evidenced by a lower zooplankton contribution to total plankton biomass and lower zooplankton:ciliate and HNF:bacteria biomass ratios. Our results suggest that a lowering of the water level in warm shallow lakes will enhance the contribution of bacteria, HNF and ciliates to the plankton biomass, likely due to increased density of submerged macrophytes (less phytoplankton); this effect will, however, be less pronounced in the presence of fish.

Keywords

Bacteria Ciliates Heterotrophic nanoflagellates Macrophytes Phytoplankton 

Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Arda Özen
    • 1
    • 2
    • 3
  • Tuba Bucak
    • 3
  • Ülkü Nihan Tavşanoğlu
    • 3
  • Ayşe İdil Çakıroğlu
    • 3
  • Eti Ester Levi
    • 3
  • Jan Coppens
    • 3
  • Erik Jeppesen
    • 4
    • 5
    • 6
  • Meryem Beklioğlu
    • 3
    • 7
  1. 1.Department of Forest EngineeringCankiri Karatekin UniversityÇankırıTurkey
  2. 2.Department of Biology, Faculty of ScienceAtatürk UniversityErzurumTurkey
  3. 3.Limnology Laboratory, Department of BiologyMiddle East Technical University, Üniversiteler MahallesiAnkaraTurkey
  4. 4.Department of Bioscience and the Arctic Centre (ARC)Aarhus UniversitySilkeborgDenmark
  5. 5.Greenland Climate Research Centre (GCRC)Greenland Institute of Natural ResourcesNuukGreenland
  6. 6.Sino-Danish Centre for Education and Research (SDC)BeijingChina
  7. 7.Kemal Kurdaş Ecological Research and Training Stations, Lake EymirMiddle East Technical UniversityAnkaraTurkey