• Record: found
  • Abstract: found
  • Article: found
Is Open Access

Impact of Summer Cattle Grazing on the Sierra Nevada Watershed: Aquatic Algae and Bacteria

Read this article at

      There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


      Introduction. We evaluated periphytic algal and microbial communities to assess the influence of human and cattle impact on Sierra water quality. Methods. 64 sites (lakes and streams from Lake Tahoe to Sequoia National Park, California) were sampled for suspended indicator bacteria and algae following standardized procedures. The potential for nonpoint pollution was divided into three categories: cattle-grazing areas (C), recreation use areas (R), or remote wildlife areas (W). Results. Periphyton was found at 100% of C sites, 89% of R sites, but only 25% of W sites. Eleven species of periphytic algae were identified, including Zygnema, Ulothrix, Chlorella, Spirogyra, mixed Diatoms, and Cladophoria. Mean benthic algae coverage was 66% at C sites compared to 2% at W sites (P < 0.05). The prevalence of E. coli associated with periphyton was 100% at C sites, 25% of R sites, and 0% of W sites. Mean E. coli CFU/gm of algae detected was: C = 173,000, R = 700, W = 0. (P < 0.05). Analysis of neighboring water for E. coli bacteria >100 CFU/100 mL: C = 91%, R = 8%, W = 0 (P < 0.05). Conclusion. Higher periphytic algal biomass and uniform presence of periphyton-attached E. coli corresponded to watersheds exposed to summer cattle grazing. These differences suggest cattle grazing compromises water quality.

      Related collections

      Most cited references 47

      • Record: found
      • Abstract: not found
      • Article: not found

      Ecology. Controlling eutrophication: nitrogen and phosphorus.

        • Record: found
        • Abstract: not found
        • Article: not found

        Ecological Costs of Livestock Grazing in Western North America

          • Record: found
          • Abstract: not found
          • Article: not found

          Top-Down and Bottom-Up Control of Stream Periphyton: Effects of Nutrients and Herbivores


            Author and article information

            1Department of Environmental Science and Policy and the John Muir Institute of the Environment, University of California, Davis, CA 95616, USA
            2Department of Emergency Medicine, University of California Davis Medical Center, 4150 V Street, PSSB 2100, Sacramento, CA 95817, USA
            Author notes
            *Robert W. Derlet: rwderlet@

            Academic Editor: Pam R. Factor-Litvak

            J Environ Public Health
            J Environ Public Health
            Journal of Environmental and Public Health
            Hindawi Publishing Corporation
            21 February 2012
            : 2012
            Copyright © 2012 Robert W. Derlet et al.

            This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

            Research Article

            Public health


            Comment on this article