Waterfowl abundance does not predict the dominant avian source of beach Escherichia coli.
The horizontal, fluorophore enhanced, rep-PCR (HFERP) DNA fingerprinting technique was used to identify potential sources of  in water, nearshore sand, and sediment at two beaches in the Duluth-Superior Harbor, near Duluth, MN, and Superior, WI, during May, July, and September 2006. An animal or environmental source could be identified for 35, 29, and 30% of  strains in water, sand, and sediments, respectively. Waterfowl, including Canada geese, ring-billed gulls, and mallard ducks, were the largest source of  that could be identified in water (55-100%), sand (59-100%), and sediment (92-100%) at both beaches. Although ring-billed gulls were more abundant in this harbor, Canada geese were usually the dominant source of waterfowl  found at these beaches. The percentage of  identified from treated wastewater was always less than the percentage of  originating from waterfowl. At both beaches, the percentage of  in water contributed by treated wastewater was higher in May compared with July and September. The larger proportion of wastewater-derived  seen in May probably reflected a smaller contribution of  from geese when these birds were less abundant rather than an absolute increase in  from treated wastewater. Microbial source analysis and bird census data both indicated that waterfowl were a major source of  at beaches in the Duluth-Superior Harbor. These data also indicated it is risky to assume that the most abundant waterfowl species present in waterways will also be the largest source of avian-derived  in water, nearshore sand, and sediments at beaches.
Department of Biology, University of Minnesota Duluth, Duluth, MN, USA.
Dennis L
DL
Hansen
Satoshi
S
Ishii
Michael J
MJ
Sadowsky
Randall E
RE
Hicks
D000818:Animals; D046090:Anseriformes / Q000502:physiology*; D001493:Bathing Beaches; D046091:Charadriiformes / Q000502:physiology*; D004926:Escherichia coli / Q000145:classification* / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology; D019015:Geologic Sediments / Q000382:microbiology; D060106:Lakes; D008910:Minnesota; D011156:Population Density; D012822:Silicon Dioxide; D013696:Temperature; D014865:Waste Disposal, Fluid; D014871:Water Microbiology
D012822:Silicon Dioxide