title: Abiotic autumnal organic matter deposition and grazing disturbance effects on epilithic biofilm succession.
abstract: Stream epilithic biofilm community assembly is influenced in part by environmental factors. Autumn leaf deposition is an annual resource subsidy to streams, but the physical effects of leaves settling on epilithic biofilms has not been investigated.We hypothesized that bacterial and microeukaryotic community assembly would follow a successional sequence that was mediated by abiotic effects that were simulating leaf deposition (reduced light and flow) and by biotic (snail grazing)disturbance. This hypothesis was tested using an in situ experimental manipulation. Ambient biofilms had greater algal biomass and distinct ARISA community profiles compared to biofilms developed under manipulated conditions. There were no significant differences in biofilm characteristics associated with grazing, suggesting that results were driven by reduced light/flow rather than invertebrate disturbance; however, grazing appeared to increase bacterial taxon richness.Interestingly at day 38, all treatments grouped together in ordination space and had similar algal/total biomass ratios. We suggest that algal priming promoted a shift in ambient biofilms but that this effect is dependent upon successional timing of algal establishment. These data demonstrate that abiotic effects were more influential than local grazing disturbance and imply that leaf litter deposition may have bottom-up effects on the stream ecosystem through altered epilithic biofilms.
authors.affiliation: Department of Biology, University of Dayton, Dayton, OH 45469-2320, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Lang
authors.affiliation: Department of Biology, University of Dayton, Dayton, OH 45469-2320, USA.
authors.forename: Ryan W
authors.initials: RW
authors.lastname: McEwan
authors.affiliation: Department of Entomology and Department of Osteopathic Medical Specialties, Michigan State University, 243 Natural Science Bldg., 288 Farm Lane, East Lansing, MI 48824, USA benbow@msu.edu.
authors.forename: M Eric
authors.initials: ME
authors.lastname: Benbow
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D001483:Base Sequence; D018441:Biofilms / Q000145:classification / Q000254:growth & development*; D018533:Biomass; D004269:DNA, Bacterial / Q000235:genetics; D017753:Ecosystem; D060434:Herbivory / Q000502:physiology*; D059013:Microbial Consortia / Q000235:genetics*; D018515:Plant Leaves / Q000382:microbiology*; D012621:Seasons; D017422:Sequence Analysis, DNA; D012908:Snails / Q000502:physiology; D014197:Trees
chemical_list: D004269:DNA, Bacterial
keywords: 454 pyrosequencing; ARISA; invertebrate grazing; leaf deposition; periphyton; priming effect