title: The effect of top-predator presence and phenotype on aquatic microbial communities.
abstract: The presence of predators can impact a variety of organisms within the ecosystem, including microorganisms. Because the effects of fish predators and their phenotypic differences on microbial communities have not received much attention, we tested how the presence/absence, genotype, and plasticity of the predatory three-spine stickleback (Gasterosteus aculeatus) influence aquatic microbes in outdoor mesocosms. We reared lake and stream stickleback genotypes on contrasting food resources to adulthood, and then added them to aquatic mesocosm ecosystems to assess their impact on the planktonic bacterial community. We also investigated whether the effects of fish persisted following the removal of adults, and the subsequent addition of a homogenous juvenile fish population. The presence of adult stickleback increased the number of bacterial OTUs and altered the size structure of the microbial community, whereas their phenotype affected bacterial community composition. Some of these effects were detectable after adult fish were removed from the mesocosms, and after juvenile fish were placed in the tanks, most of these effects disappeared. Our results suggest that fish can have strong short-term effects on microbial communities that are partially mediated by phenotypic variation of fish.
authors.affiliation: Department of Surface Waters-Research and Management Center for Ecology, Evolution and Biogeochemistry Eawag Swiss Federal Institute of Aquatic Science and Technology Kastanienbaum Switzerland; Zoological Institute University of Basel Basel Switzerland.
authors.forename: Karen E
authors.identifier: 0000-0002-1130-2093
authors.initials: KE
authors.lastname: Sullam
authors.affiliation: Eawag Aquatic Ecology Department Center for Ecology, Evolution and Biogeochemistry Kastanienbaum Switzerland.
authors.forename: Blake
authors.initials: B
authors.lastname: Matthews
authors.affiliation: Eawag Department of Fish Ecology and Evolution Center for Ecology, Evolution and Biogeochemistry Kastanienbaum Switzerland; Aquatic Ecology and Evolution Institute of Ecology & Evolution University of Bern Bern Switzerland; Department of Biology University of Fribourg Fribourg Switzerland.
authors.forename: Thierry
authors.initials: T
authors.lastname: Aebischer
authors.affiliation: Eawag Department of Fish Ecology and Evolution Center for Ecology, Evolution and Biogeochemistry Kastanienbaum Switzerland; Aquatic Ecology and Evolution Institute of Ecology & Evolution University of Bern Bern Switzerland.
authors.forename: Ole
authors.initials: O
authors.lastname: Seehausen
authors.affiliation: Department of Surface Waters-Research and Management Center for Ecology, Evolution and Biogeochemistry Eawag Swiss Federal Institute of Aquatic Science and Technology Kastanienbaum Switzerland.
authors.forename: Helmut
authors.initials: H
authors.lastname: Bürgmann
keywords: Gasterosteus aculeatus; bacterial community composition; ecosystem effects; mesocosms; stickleback