Fw: From Science News Online

[Richard L Whitman <rwhitman@usgs.gov>]

                      <bharder@sciencen                                                                       
                      ews.org>                 To:       <rwhitman@usgs.gov>                                  
                                               cc:                                                            
                      07/05/2005 09:11         Subject:  From Science News Online                             
                      AM                                                                                      
                                                                                                              




Dear Richard,
  Thanks again for your help in interpreting this research and putting
  it in context. I tried to squeeze in a comment about wind also
  whipping up waves to similar effect, but it didn't make the final
  round of cuts.

  Please keep me posted on your work, though. I might have an
  opportunity to write another story on the topic in the future.

  Cheers,
  Ben

  ---------------------------------

  Science News Online

  Week of July 2, 2005; Vol. 168, No. 1

  Bacteria Ride the Tide: Moon's phases predict water quality at beaches

  Ben Harder

  At many ocean beaches, full and new moons coincide with the greatest
  concentrations of bacteria in the water, researchers in California
  have determined. The new finding suggests that extreme tides, which
  occur fortnightly in synchrony with lunar phases, generate water
  conditions that could make swimmers sick.

  To prevent waterborne microbes from causing diarrhea and other
  illnesses, authorities at U.S. beaches periodically test
  concentrations of bacteria such as enterococci and temporarily close
  sites where samples exceed regulatory limits. While most enterococci
  aren't pathogenic, studies link their prevalence to the risk of
  infections from other waterborne microbes. Last year, closures
  affected 1,000 ocean and freshwater beaches out of the 3,400 that are
  monitored nationwide.

  However, microbial concentrations fluctuate rapidly, and it takes a
  day or more to cultivate and count bacteria from a given sample.
  Often as a result, says Alexandria B. Boehm of Stanford University, a
  "pollution event is gone by the time the sign goes up" warning
  beachgoers to stay out of the water.

  To assess whether information about tides could be useful in
  predicting water quality, Boehm and Stephen B. Weisberg of the
  Southern California Coastal Water Research Project in Westminster
  assembled data for 60 beach sites along 120 kilometers of the
  southern California coast. For each site, enterococci had been
  measured in samples taken daily or weekly for several years. The
  researchers recorded the phase of the moon, tidal conditions, and
  other characteristics associated with each sample.

  At most sites, so-called spring tides&#151;those associated with full
  and new moons&#151;significantly elevated average enterococci
  concentrations and more than doubled the likelihood that a sample
  would exceed regulatory standards. The negative effect on water
  quality was greatest when a spring tide was going out, or ebbing,
  Boehm and Weisberg report in an upcoming Environmental Science &
  Technology.

  It's not surprising that the highest bacterial concentration "shows
  up at low tide during an exaggerated tidal cycle, when the sea water
  is at its lowest ebb," says coastal oceanographer Willard S. Moore of
  the University of South Carolina in Columbia. During ebb tides, the
  open ocean receives subterranean waters, which can be rich in
  microbes and their nutrients, he says.

  Richard L. Whitman, an ecologist at the U.S. Geological Survey in
  Porter, Ind., offers an alternative explanation. The wave action
  enhanced by the tide stirs up bacteria in the sand, he says.

  "If you're risk averse," Boehm says, "avoid going to the beach during
  spring tides, and particularly during spring ebb tides."

  That's good advice, says Whitman. But he cautions that nobody
  directly monitors disease-causing bacteria, so the link between tides
  and risk isn't confirmed.

  The Environmental Protection Agency already advises people not to
  swim at beaches after heavy rains, which dump bacteria into the
  water.

  If you have a comment on this article that you would like considered
  for publication in Science News, send it to editors@sciencenews.org.
  Please include your name and location.

  References:

  Boehm, A.B., and S.B. Weisberg. In press. Tidal forcing of
  enterococci at marine recreational beaches at fortnightly and
  semidiurnal frequencies. Environmental Science & Technology. Abstract
  available at http://pubs.acs.org/cgi-bin/abstract.cgi/
  esthag/asap/abs/es048175m.html.

  Wade, T.J., et al. 2003. Do U.S. Environmental Protection Agency
  water quality guidelines for recreation waters prevent
  gastrointestinal illness? A systematic review and meta-analysis.
  Environmental Health Perspectives 111(June):1102-1109. Available at
  http://ehp.niehs.nih.gov/docs/2003/6241/abstract.html.

  Further Readings:

  U.S. Environmental Protection Agency. 2004. Before you go to the
  beach..." Available at
  http://www.epa.gov/waterscience/beaches/30cwabeach.pdf.

  Information on EPA beach standards, monitoring, and notification is
  available at http://www.epa.gov/ost/beaches/.

  Sources:

  Alexandria B. Boehm
  Department of Civil and Environmental Engineering
  Terman Engineering Center M7
  Stanford University
  Stanford, CA 94305-4020

  William C. Burnett
  Department of Oceanography
  OSB-0319, Mail Code 4320
  Florida State University
  Tallahassee, FL 32306

  Willard S. Moore
  Department of Geological Sciences
  EWSC, Room 411
  University of South Carolina
  Columbia, SC 29208

  Stephen B. Weisberg
  Southern California Coastal Water Research Project
  7171 Fenwick Lane
  Westminster, CA 92683

  Richard L. Whitman
  USGS Great Lakes Science Center
  Lake Michigan Ecological Research Station
  1100 North Mineral Springs Road
  Porter, IN 46304

  http://www.sciencenews.org/articles/20050702/fob5.asp

  From Science News, Vol. 168, No. 1, July 2, 2005, p. 4.

  Copyright (c) 2005 Science Service.  All rights reserved.

  ---------------------------------

  Interested in new developments in science and technology? Consider
  subscribing to Science News. Visit Science News Online at
  http://www.sciencenews.org/ for access to additional news articles and
  subscription information.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
beachnet is hosted by the Great Lakes Information Network:
http://www.great-lakes.net
To unsubscribe from this list: send mail to majordomo@great-lakes.net
with the command 'unsubscribe beachnet' in the body of your message. No
quotes or subject line are required.
About : http://www.great-lakes.net/lists/beachnet/beachnet.info
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *