Transcript Figure 2 - San Mateo County Community College District

Distribution Of Fecal Coliform Bacteria in A Central California Coastal Stream
Tim Viray, Eric Fung, and Christine Case
Biology Department, Skyline College, San Bruno CA
Abstract
Materials & Methods
Results
Pillar Point is a popular recreation area and one of the most contaminated
beaches along the central California coast. This study was undertaken to locate
the source of fecal contamination at Pillar Point. Identifying the source of fecal
contamination in coastal creeks is important for protecting the health of
swimmers and the coastal ecosystem. Frenchman’s Creek is the only stream that
drains the Coast Ranges into the ocean at Pillar Point. The creek flows from
coastal sage scrub, through rural and suburban watersheds, to the ocean. We
conducted a systematic survey of water, soil, and vegetation along the 4-km
creek from headwaters to estuary. Coliform and Enterococcus bacteria were used
as indicators of fecal contamination. Total coliform and fecal coliform bacteria
were counted using the multiple-tube method. A membrane-filtration test was
used to determine enterococcal numbers in the samples. Fecal contamination
begins approximately 0.8 km upstream from the estuary; heavy contamination
was detected at three of the sites investigated. In these sites, total coliforms
exceed 2400/100 mL and enterococci exceed 80/100 mL. Fecal coliforms (from
mammals) were found at these sites. Coliform counts are being performed on
soil and aquatic vegetation to determine whether these are reservoirs for fecal
coliform bacteria or the fecal coliforms are from land-based anthropogenic
sources.
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Water samples were collected along Frenchman’s Creek from headwaters to
the estuary between April and July 2011 (Figure 2).
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Samples were collected by washing 480 mL plastic bottles and collecting
approximately 240 mL of the creek’s water.
Fecal contamination was found in sites 3, 4, and 5 (Figures 3 and 4), which
indicates that the source of contamination is nearer the estuary than the
headwaters.
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Soil and plant samples were also collected around the area where water
samples were collected and placed in zip-lock bags.
No coliforms were found in plant and soil samples collected at sites 3, 4, and
5.
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Coliform counts were performed on water, plant, and soil samples using the
multiple-tube method with lauryl-sulfate lactose broth.
Methylumbelliferone glucuronide (MUG) agar incubated at 44±0.5°C was
used for the confirming test (2).
Enteroccocus bacteria are present and abundant in the sites where fecal
contamination was found (Figure 4).
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Higher coliforms counts were found during periods of rainfall suggesting
stormwater runoff as the source of contamination (Figure 5).
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The membrane filter technique was used on the water sample to determine
enteroccoci on Enterococcus Agar and E. coli on Endo Agar (2).
Discussion & Conclusion
Figure 3. Coliform counts along Frenchman’s Creek. The sites shown in red had
fecal coliforms present.
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During the summer and fall season, local farmers raise the dam between sites
3 and 4 (Figure 2) to provide irrigation water.
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The water level was raised by 15–20 feet, which covered multiple smaller
water runoffs that could be possible sources of the contamination.
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We cannot confirm the exact location of the contamination but we have
narrowed the source to sites 4 and 5.
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We confirmed that soil or riparian vegetation are not reservoirs for the fecal
bacteria, which infers that the contamination is from land-based
anthropogenic sources.
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The higher coliform counts found during periods of rainfall suggest that
stormwater drainage contributes to contamination of the creek.
Aim
To determine the source of fecal contamination into Frenchman’s Creek.
Future Studies
Background
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Pillar Point is listed as one of the 10 most polluted beaches in San Mateo
County (1).
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Illnesses associated with fecal pollution include skin rashes, respiratory
infection, meningitis, gastroenteritis, and hepatitis (1). These illnesses are
transmitted by water contact sports and from consuming marine animals.
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Fecal contamination at Pillar Point Harbor threatens commercial fishing and
recreation (7).
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Frenchman’s Creek (Figure 1) is a major contributor to the fecal distribution
of Pillar Point (1).
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Sampling at the tunnel/storm drain that links to a florist warehouse/greenhouse. This runoff from the florist could be the source of the contamination.
This site is between sample sites 4 and 5.
Literature Cited
Figure 4. Sites of fecal contamination from mammals.
Coliforms are aerobic or facultatively anaerobic, gram-negative, nonendospore-forming, rod shaped bacteria that ferment lactose to form gas
within 48 hr of being placed in lactose broth at 35-37°C. Fecal coliforms are
found in the human intestines. They produce the enzyme -glucuronidase
when put on a methylumbelliferyl--D-glucuronide at 44.5°C. Total
coliforms include fecal coliforms as well as coliforms that grow at 35-37°C
(3).
Escherichia coli and enteroccoci are used as indicator organisms for fecal
contamination because they are found in the intestines of warm-blooded
animals (5).
1.
Brennan, S,. August 2010. “Ten most polluted beaches in San Mateo County.” Coastsider.
http://coastsider.com (5 June 2011).
2.
Clesceri, L. S. and A. E. Greenberg, and A. D. Eaton (eds). Standard methods for the
examination of water and wastewater, 20th ed. Washington, D. C.: American Public Health
Association, 1999.
3.
Holt, J. G. (ed.) Bergey's Manual of Determinative Bacteriology, 9th ed. Baltimore: Williams
& Wilkins, 1994.
4.
National Research Council (U.S.). From Monsoons to Microbes: Understanding the Ocean’s
Role in Human Health. National Academy Press, Washington D.C., 1999.
5.
O’Brien, D. 2011. “A Better To Track Salmonella and E. coli in Waterways.” Agricultural
Research Magazine 206: 8.
6.
Perry, A. 2011. E. coli: Alive and Well, Probably in a Streambed Near You.” Agricultural
Research Magazine 211: 20.
7.
“Pillar Point Harbor.” 1998-2004. San Mateo County Harbor District.
http://www.smharbor.com/pillarpoint/ (29 July 2011).
Acknowledgements
E. coli can survive in waterways in the biofilms that form on some most
surfaces (6).
Enterococci are facultatively anaerobic, gram-positive cocci in Lancefield
group D. They can also be found in soil, water, food, and are a significant
component of human intestinal microbiota (3).
Locating storm drains or sewage cross-connections along the creek can be
done to verify whether these factors contribute to the contamination.
agricultural and suburban developments to the Pacific Ocean. This is the site
where the MPN for both fecal coliforms and enterococci is at its highest.
Transfer of pathogenic bacteria among fishes and other marine organisms can
directly affect humans (4).
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Figure 1. Frenchman’s Creek. The water runs from coastal scrub through
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Figure 2. Collection sites along Frenchman’s Creek. USGS 7.5-
minute quadrangles Montara Mountain and Half Moon Bay.
Figure 5. Coliform counts relative to rainfall. The highest coliform counts were
found at sites 2, 4, and 5
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Skyline MESA and SACNAS for supporting our project
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Colleagues with whom we worked countless hours during the entire spring and summer
semesters
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Pat Carter for providing us with all the materials we need to do our experiment well
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Professor Christine Case who inspired us to do our best and pushed us to go beyond ourselves
to get better.