Microbial Ecology

, Volume 62, Issue 3, pp 574–583

Terrestrial Sources Homogenize Bacterial Water Quality During Rainfall in Two Urbanized Watersheds in Santa Barbara, CA

Authors

    • Donald Bren School of Environmental Science and ManagementUniversity of California
    • Earth Research InstituteUniversity of California
  • Laurie C. Van De Werfhorst
    • Donald Bren School of Environmental Science and ManagementUniversity of California
    • Earth Research InstituteUniversity of California
  • Jill L. S. Murray
    • City of Santa Barbara, Creeks Restoration and Water Quality Improvement Division
  • Patricia A. Holden
    • Donald Bren School of Environmental Science and ManagementUniversity of California
    • Earth Research InstituteUniversity of California
Environmental Microbiology

DOI: 10.1007/s00248-011-9874-z

Cite this article as:
Sercu, B., Van De Werfhorst, L.C., Murray, J.L.S. et al. Microb Ecol (2011) 62: 574. doi:10.1007/s00248-011-9874-z

Abstract

Microbiological contamination from runoff is a human health concern in urbanized coastal environments, but the contamination sources are often unknown. This study quantified fecal indicator bacteria and compared the distributions of human-specific genetic markers and bacterial community composition during dry and wet weather in urban creeks draining two neighboring watersheds in Santa Barbara, CA. In a prior study conducted during exclusively dry weather, the creeks were contaminated with human waste as indicated by elevated numbers of the human-specific Bacteroidales marker HF183 (Sercu et al. in Environ Sci Technol 43:293–298, 2009). During the storm, fecal indicator bacterial numbers and loads increased orders of magnitude above dry weather conditions. Moreover, bacterial community composition drastically changed during rainfall and differed from dry weather flow by (1) increased bacterial diversity, (2) reduced spatial heterogeneity within and between watersheds, and (3) clone library sequences more related to terrestrial than freshwater taxa. Finally, the spatial patterns of human-associated genetic markers (HF183 and Methanobrevibacter smithii nifH gene) changed during wet weather, and the contribution of surface soils to M. smithii nifH gene detection was suspected. The increased fecal indicator bacteria numbers during wet weather were likely associated with terrestrial sources, instead of human waste sources that dominated during dry weather flow.

Supplementary material

248_2011_9874_MOESM1_ESM.doc (400 kb)
ESM 1(DOC 400 kb)

Copyright information

© Springer Science+Business Media, LLC 2011