title: Diversity, composition, and geographical distribution of microbial communities in California salt marsh sediments.
abstract: The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the California coastline were characterized using phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Additionally, 27 metals, six currently used pesticides, total polychlorinated biphenyls and polycyclic aromatic hydrocarbons, chlordanes, nonachlors, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene were analyzed. Sampling was performed over large (between salt marshes), medium (stations within a marsh), and small (different channel depths) spatial scales. Regression and ordination analysis suggested that the spatial variation in microbial communities exceeded the variation attributable to pollutants. PLFA analysis and TRFLP canonical correspondence analysis (CCA) explained 74 and 43% of the variation, respectively, and both methods attributed 34% of the variation to tidal cycles, marsh, year, and latitude. After accounting for spatial variation using partial CCA, we found that metals had a greater effect on microbial community composition than organic pollutants had. Organic carbon and nitrogen contents were positively correlated with PLFA biomass, whereas total metal concentrations were positively correlated with biomass and diversity. Higher concentrations of heavy metals were negatively correlated with branched PLFAs and positively correlated with methyl- and cyclo-substituted PLFAs. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential for using microbial community analyses in assessments of the ecosystem health of salt marshes.
authors: Department of Land, Air and Water Resources, 1110 PES Building, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA. anacordova@ucdavis.edu
authors: Ana Lucía
authors: AL
authors: Córdova-Kreylos
authors: Yiping
authors: Y
authors: Cao
authors: Peter G
authors: PG
authors: Green
authors: Hyun-Min
authors: HM
authors: Hwang
authors: Kathryn M
authors: KM
authors: Kuivila
authors: Michael G
authors: MG
authors: Lamontagne
authors: Laurie C
authors: LC
authors: Van De Werfhorst
authors: Patricia A
authors: PA
authors: Holden
authors: Kate M
authors: KM
authors: Scow