title: Long-term monitoring of molecular markers can distinguish different seasonal patterns of fecal indicating bacteria sources.
abstract: Elevated levels of fecal indicator bacteria (FIB) have been observed at Topanga Beach, CA, USA. To identify the FIB sources, a microbial source tracking study using a dog-, a gull- and two human-associated molecular markers was conducted at 10 sites over 21 months. Historical data suggest that episodic discharge from the lagoon at the mouth of Topanga Creek is the main source of bacteria to the beach. A decline in creek FIB/markers downstream from upper watershed development and a sharp increase in FIB/markers at the lagoon sites suggest sources are local to the lagoon. At the lagoon and beach, human markers are detected sporadically, dog marker peaks in abundance mid-winter, and gull marker is chronically elevated. Varied seasonal patterns of FIB and source markers were identified showing the importance of applying a suite of markers over long-term spatial and temporal sampling to identify a complex combination of sources of contamination.
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA. Electronic address: triedel@utexas.edu.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Riedel
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Thulsiraj
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA; Institute of the Environment and Sustainability, University of California Los, Angeles, Los Angeles, CA 90095, USA.
authors.forename: Amity G
authors.initials: AG
authors.lastname: Zimmer-Faust
authors.affiliation: Resource Conservation District of the Santa Monica Mountains, PO Box 638, Agoura Hills, CA 91301, USA.
authors.forename: Rosi
authors.initials: R
authors.lastname: Dagit
authors.affiliation: Resource Conservation District of the Santa Monica Mountains, PO Box 638, Agoura Hills, CA 91301, USA.
authors.forename: Jenna
authors.initials: J
authors.lastname: Krug
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA.
authors.forename: Kaitlyn T
authors.initials: KT
authors.lastname: Hanley
authors.affiliation: Resource Conservation District of the Santa Monica Mountains, PO Box 638, Agoura Hills, CA 91301, USA.
authors.forename: Krista
authors.initials: K
authors.lastname: Adamek
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA.
authors.forename: Darcy L
authors.initials: DL
authors.lastname: Ebentier
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Torres
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA.
authors.forename: Uriel
authors.initials: U
authors.lastname: Cobian
authors.affiliation: UCLA High School Summer Research Program, The Henry Samueli School of Engineering & Applied Science, Office of Academic & Student Affairs, Room 6426, Boelter Hall, Los Angeles, CA 90095, USA.
authors.forename: Sophie
authors.initials: S
authors.lastname: Peterson
authors.affiliation: Department of Civil and Environmental Engineering, University of California Los, Angeles, Los Angeles, CA 90095, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Jay
mesh_terms: D000818:Animals; D001439:Bacteroides / Q000302:isolation & purification; D001493:Bathing Beaches; D002140:California; D046091:Charadriiformes; D004285:Dogs; D004755:Enterobacteriaceae / Q000302:isolation & purification; D056569:Enterococcaceae / Q000302:isolation & purification; D004784:Environmental Monitoring; D005243:Feces / Q000737:chemistry / Q000382:microbiology*; D006801:Humans; D045483:Rivers / Q000382:microbiology; D012621:Seasons; D014871:Water Microbiology; D014873:Water Pollutants / Q000302:isolation & purification*
chemical_list: D014873:Water Pollutants
keywords: FIB; Long-term; MST; Molecular markers; Topanga; qPCR