title: Cyanobacteria facilitate parasite epidemics in Daphnia.
abstract: The seasonal dominance of cyanobacteria in the phytoplankton community of lake ecosystems can have severe implications for higher trophic levels. For herbivorous zooplankton such as Daphnia, cyanobacteria have poor nutritional value and some species can produce toxins affecting zooplankton survival and reproduction. Here we present another, hitherto largely unexplored aspect of cyanobacteria, namely that they can increase Daphnia susceptibility to parasites. In a 12-yr monthly time-series analysis of the Daphnia community in Greifensee (Switzerland), we observed that cyanobacteria density correlated significantly with the epidemics of a common gut parasite of Daphnia, Caullerya mesnili, regardless of what cyanobacteria species was present or whether it was colonial or filamentous. The temperature from the previous month also affected the occurrence of Caullerya epidemics, either directly or indirectly by the promotion of cyanobacterial growth. A laboratory experiment confirmed that cyanobacteria increase the susceptibility of Daphnia to Caullerya, and suggested a possible involvement of cyanotoxins or other chemical traits of cyanobacteria in this process. These findings expand our understanding of the consequences of toxic cyanobacterial blooms for lake ecosystems and might be relevant for epidemics experienced by other aquatic species.
authors.affiliation: Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, CH-8600, Switzerland.|School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: C
authors.identifier: http://orcid.org/0000-0002-9088-2187
authors.initials: C
authors.lastname: Tellenbach
authors.affiliation: Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, CH-8600, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Tardent
authors.affiliation: Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, CH-8600, Switzerland.|Institute of Integrative Biology, ETH Zurich, Zurich, 8092, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Pomati
authors.affiliation: Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, CH-8600, Switzerland.|Department of Systematic and Evolutionary Botany, University of Zurich, Zürich, 8008, Switzerland.
authors.forename: B
authors.initials: B
authors.lastname: Keller
authors.affiliation: Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, CH-8600, Switzerland.|Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA.
authors.forename: N G
authors.initials: NG
authors.lastname: Hairston
authors.affiliation: Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 301, Berlin, 12587, Germany.|Department of Biology, Chemistry and Pharmacy, Institute of Biology, Freie Universitat Berlin, Königin-Luise-Strasse 1-3, Berlin, 14195, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wolinska
authors.affiliation: Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, CH-8600, Switzerland.|Institute of Integrative Biology, ETH Zurich, Zurich, 8092, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Spaak
mesh_terms: D000818:Animals; D000458:Cyanobacteria / Q000502:physiology*; D003621:Daphnia / Q000469:parasitology*; D006790:Host-Parasite Interactions; D050298:Mesomycetozoea / Q000502:physiology*; D012621:Seasons; D013997:Time Factors
keywords: 
  Caullerya mesnili
  ; epidemiology; host-parasite interactions; time series analysis; toxins; zooplankton