title: Stratification and loading of fecal indicator bacteria (FIB) in a tidally muted urban salt marsh.
abstract: Stratification and loading of fecal indicator bacteria (FIB) were assessed in the main tidal channel of the Ballona Wetlands, an urban salt marsh receiving muted tidal flows, to (1) determine FIB concentration versus loading within the water column at differing tidal flows, (2) identify associations of FIB with other water quality parameters, and (3) compare wetland FIB concentrations to the adjacent estuary. Sampling was conducted four times during spring-tide events; samples were analyzed for FIB and turbidity (NTU) four times over a tidal cycle at pre-allocated depths, depending on the water level. Additional water quality parameters measured included temperature, salinity, oxygen, and pH. Loadings were calculated by integrating the stratified FIB concentrations with water column cross-sectional volumes corresponding to each depth. Enterococci and Escherichia coli were stratified both by concentration and loading, although these variables portrayed different patterns over a tidal cycle. Greatest concentrations occurred in surface to mid-strata levels, during flood tides when contaminated water flowed in from the estuary, and during ebb flows when sediments were suspended. Loading was greatest during flood flows and diminished during low tide periods. FIB concentrations within the estuary often were significantly greater than those within the wetland tide channel, supporting previous studies that the wetlands act as a sink for FIB. For public health water quality monitoring, these results indicate that more accurate estimates of FIB concentrations would be obtained by sampling a number of points within a water column rather than relying only on single surface samples.
authors: The Bay Foundation, 1 LMU Dr, Los Angeles, CA, 90045, USA, kjohnston@santamonicabay.org.
authors: Karina K
authors: KK
authors: Johnston
authors: John H
authors: JH
authors: Dorsey
authors: Jose A
authors: JA
authors: Saez
mesh_terms: D001419:Bacteria / Q000145:classification / Q000254:growth & development*; D003430:Cross-Sectional Studies; D016983:Enterococcus / Q000254:growth & development; D004784:Environmental Monitoring / Q000379:methods*; D004926:Escherichia coli / Q000254:growth & development; D063366:Estuaries; D005243:Feces / Q000382:microbiology; D014871:Water Microbiology; D014876:Water Pollution / Q000032:analysis* / Q000706:statistics & numerical data; D053833:Wetlands
references: Mar Pollut Bull. 2006 Aug;52(8):881-91
references: 16406429
references: Can J Microbiol. 2009 Dec;55(12):1364-74
references: 20029528
references: Environ Sci Technol. 2008 May 15;42(10):3609-14
references: 18546697
references: Environ Sci Technol. 2005 Dec 1;39(23):9083-93
references: 16382928
references: Environ Sci Technol. 2006 Aug 15;40(16):4851-8
references: 16955877
references: Water Res. 2005 Sep;39(14):3394-408
references: 16051310
references: J Appl Microbiol. 2004;96(3):464-72
references: 14962126
references: J Environ Qual. 2013 Jan-Feb;42(1):229-38
references: 23673758
references: Water Res. 2008 Feb;42(4-5):941-50
references: 17945328
references: Appl Environ Microbiol. 2002 Mar;68(3):1122-31
references: 11872459
references: Environ Sci Technol. 2010 Jan 15;44(2):631-7
references: 20028091
references: Appl Environ Microbiol. 2001 Jan;67(1):179-84
references: 11133443
references: Environ Monit Assess. 2013 Mar;185(3):2647-69
references: 22766922
references: Environ Sci Technol. 2002 Sep 15;36(18):3885-92
references: 12269739
references: J Water Health. 2011 Jun;9(2):265-78
references: 21942192
references: Environ Manage. 2007 Jun;39(6):867-75
references: 17453279
references: Environ Monit Assess. 2009 Jul;154(1-4):337-48
references: 18563603
references: Environ Sci Technol. 2004 May 1;38(9):2626-36
references: 15180059
references: Water Res. 2003 Feb;37(3):589-608
references: 12688694
references: J Appl Microbiol. 2002;93(5):864-71
references: 12392534
references: Appl Environ Microbiol. 1999 Dec;65(12):5628-30
references: 10584032
references: Water Res. 2006 Feb;40(3):475-86
references: 16386284
references: Water Res. 2010 Aug;44(15):4630-42
references: 20591461
references: Environ Sci Technol. 2001 Jun 15;35(12):2407-16
references: 11432541
references: Clin Microbiol Rev. 2003 Jan;16(1):129-43
references: 12525429
references: Environ Monit Assess. 2009 Aug;155(1-4):477-92
references: 18704731
references: Environ Toxicol Chem. 2013 Feb;32(2):320-8
references: 23161663