Dr. René Sahm (geb. Gergs)

Former member Fish and Freshwater Ecology
Visiting hours: via email

Research Interests

My main research area is the ecology and biodiversity of freshwater systems (Limnology) with a special focus on

  • macroinvertebrate communities
  • fish ecology
  • freshwater food web structure
  • aquatic ecotoxicology

I am also interested in the phylogeography and effects of invasive invertebrates also with regard to their limits in range extension. In doing so I use a wide range of methods to consider different point of views, including:

  • genetic analyses
  • stable isotope analyses
  • micro- and mesososm experiments
  • field surveys

Academic History

  • Since January 2015 at the Artificial Pond and stream system of the Federal Environment Agency (UBA)
  • Team Leader (June 2012 until December 2014): Community Limnology
  • Research Assistant (May 2010 until December 2014):

    Institute of Environmental Science, University of Koblenz-Landau

  • Post doc (2009 until 2010)

    Research fellowship at the University of Konstanz

  • PhD (2009):

    "Dreissena polymorpha in Lake Constance: An example of a keystone engineer?"
    At the Limnological Institute of the University of Konstanz

  • Diploma (M. Sc.) (2004):

    "Quantitative analysis of the seasonal development of grazers and periphyton in a small midland stream"
    At the Limnological River Station Schlitz of the Max-Planck-Institute for Limnology

  • Study of Biology (1998 until 2004):

    Albert-Ludwigs University of Freiburg


  • Young scientist award of the German Limnological Society (DGL) 2011


  • Hydrosphere
  • Aquatic-terrestrial ecology
  • Ornithology
  • Indicator organisms

Current Research Projects

  • Parental assignment analyses of the anadromous allis shad (Alosa alosa) as success monitoring of the reestablishemnt in the River Rhine (DBU scholarship; PhD thesis Kathrin Metzner)

Former Research Projects

  • Invasive amphipods - Trophic interactions between native and invasive amphipod species in aquatic systems. more Info
  • Studies on the reestablishment of populations of the anadromous allis shad (Alosa alosa) in River Rhine. (PhD thesis Matthias Hundt) more Info
  • Zebra mussel (Dreissena polymorpha) biodeposition based food web - Implication of the filtration activity of the mussel on the benthic macroinvertebrate community and food web structure. more Info

Supervised studies

  • Pies, Alisa (2015). Age and growth determination of juvenile allis shad (Alosa alosa) in the river Rhine and Garonne, based on otholid microstructure analysis.
  • Bayer, Bastian (Bachelor thesis, 2014). Nahrungsspektrum des invasiven Amphipoden Dikerogammarus villosus - eine Studie im Rhein anhand stabiler Isotopenanalyse.
  • Gemmer, Isabelle (Diploma thesis, 2014). Is there a genetic bottleneck of the indigenious amphipod Gammarus roeselii due to the invasion of Dikerogammarus villosus in Lake Constance?
  • Schuster, Anne-Karin (Diploma thesis, 2013). Spill-over and spill-back of parasitic copepods infecting the Pacific Oyster in the Wadden Sea.
  • Schreiber, Benjamin (Diploma thesis, 2013). Studying water hardness as a factor influencing mortality of zebrafish (Danio rerio) during chemical marking with oxytetracycline and establishing an experimental design to investigate postmarking stress sensitivity of allis shad larvae (Alosa alosa) after chemical marking with alizarin red S.
  • Steinberger, Nicole (Diploma thesis, 2013). Food quality related growth of the amphipod Gammarus roeselii.
  • Metzner, Kathrin (Diploma thesis, 2012). Genetische Charakterisierung verschiedener Bachforellenpopulationen, Salmo trutta (L.), des Pfälzerwalds.
  • Koester, Meike (Diploma thesis, 2011). Development of group-specific primer for genetic gut content analyses.
  • Hanselmann, Almut J. (Diploma thesis, 2008). Impact of temperature and invertebrate predation on the population of Limnomysis benedeni in Lake Constance. (scientific supervisor)
  • Schlag, Lena (Bachelor thesis, 2008). Ammonium- and pH- tolerance of two amphipod species in Lake Constance. (scientific supervisor)

Recent Publications

ResearcherID: B-6962-2012

ResearchGate: Link

for a paper request please contact Dr. René Gergs