<br><font size=3 face="sans-serif">Forwarding this news release with an
interesting twist on exotic aquatic species....</font>
<br>
<br><font size=3 face="sans-serif">Patricia S. De Angelis, Ph.D.<br>
Botanist - Division of Scientific Authority<br>
Chair - Plant Conservation Alliance - Medicinal Plant Working Group<br>
US Fish & Wildlife Service<br>
4401 N. Fairfax Dr., Suite 750<br>
Arlington, VA 22203<br>
703-358-1708 x1753<br>
FAX: 703-358-2276<br>
Working for the conservation and sustainable use of our green natural resources.<br>
<www.nps.gov/plants/medicinal><br>
</font>
<br><font size=3 face="sans-serif">- - - - - - - - - - - - - - - </font>
<br>
<br><font size=4 face="Times New Roman"><b>U.S. Department of the Interior</b></font><font size=3>
</font><font size=4 face="Times New Roman"><b><br>
U.S. Geological Survey</b></font><font size=3> <br>
</font><font size=4 face="Times New Roman"><b><br>
News Release</b></font><font size=3> </font>
<p><font size=4 face="Times New Roman"><b>May 18, 2007
Nancy Rybicki 703-648-5728
</b></font><font size=4 color=#3c613e face="Times New Roman"><b><u>nrybicki@usgs.gov</u></b></font><font size=3>
</font>
<p><font size=4 face="Times New Roman"><b> Jurate
Landwehr 703-648-5893 </b></font><font size=4 color=#3c613e face="Times New Roman"><b><u>jmlandwe@usgs.gov</u></b></font><font size=3>
</font>
<p><font size=4 face="Times New Roman"><b><br>
Exotic Hydrilla Benefits Chesapeake Bay’s Ecosystem</b></font><font size=3>
<br>
</font><font size=3 face="Times New Roman"><b><br>
Editors: “Long-term changes in abundance and diversity of macrophyte
and waterfowl populations in an estuary with exotic macrophytes and improving
water quality,” is available online in the May issue of </b></font><font size=3 color=#3c613e face="Times New Roman"><b><u>ASLO:
Limnology and Oceanography</u></b></font><font size=3 face="Times New Roman"><b>,
v 52, pages 1195-1207. </b></font><font size=3><br>
</font><font size=3 face="Times New Roman"><br>
An exotic species of aquatic vegetation that was deemed a severe nuisance
when it began rapidly colonizing the Potomac River, has instead benefited
the watershed’s ecosystem, according to a study by the U.S. Geological
Survey (USGS) published in the journal <i>Limnology and Oceanography.</i></font><font size=3 color=red face="Times New Roman">
</font><font size=3 face="Times New Roman">The robust exotic hydrilla first
appeared and began to flourish in the fresh water reaches of the tidal
Potomac River just as management investments to reduce nutrient loads from
sewage treatment plants were beginning to take effect. Submerged
aquatic vegetation is an important ecosystem resource for fish and waterfowl
and it was feared that the expansion of hydrilla would impair the reemergence
of native species, but this has not proven to be the case.</font><font size=3>
<br>
</font><font size=3 face="Times New Roman"><br>
“Before and during the seventeen-year period of the study, restoration
of the Potomac has focused on reducing nitrogen loads entering the river
system and the Chesapeake Bay,” said USGS scientist Nancy Rybicki, who
with colleague Jurate Landwehr were curious how the emergence of hydrilla
would affect the benefits sought for by management investments</font><font size=3 color=#008000 face="Times New Roman">.
</font><font size=3 face="Times New Roman"> </font><font size=3> <br>
</font><font size=3 face="Times New Roman"><br>
Shortly after it first appeared in the Potomac in 1983, hydrilla produced
dense vegetation masses and, in some areas, impeded boat traffic and water
sports." More significantly, it was feared that hydrilla would interfere
with native vegetation, which is important for waterfowl, such as black
duck, a signature species in this area. </font><font size=3> <br>
</font><font size=3 face="Times New Roman"><br>
Using information from annual field surveys and aerial photographs, Rybicki
and Landwehr created a data base to document bed-by-bed which species of
vegetation were found in different sections of the Potomac River system.
They recorded the percentage of total coverage and biomass each species
attained annually. In comparing species coverage with water quality
composition, they discovered that, with the reduction of nitrogen concentration
in Potomac River, hydrilla coverage expanded but so did the diversity of
plant species found in the River. Hydrilla did not crowd out native species;
indeed, native species increased. In addition, hydrilla is a good
winter food source for waterfowl communities, which have increased significantly
over this period. </font><font size=3> <br>
</font><font size=3 face="Times New Roman"><br>
“This research is the only long-term, quantitative study of aquatic plant
biodiversity following the colonization of an exotic species in an estuary
where millions of dollars are spent annually to reduce nutrient input and
it demonstrates that exotics are not always harmful to an ecosystem,”
said Rybicki. </font><font size=3><br>
</font><font size=3 face="Times New Roman"><br>
"Furthermore," Landwehr pointed out, "the methods developed
for this study are transferable to any ecological assessments that need
to merge remotely-sensed spatial coverage with field observations."
</font><font size=3> <br>
</font><font size=3 face="Times New Roman"><br>
The findings support current federal and state management strategies to
improve water clarity and reduce nutrient loads to: enhance aquatic vegetation
coverage; increase waterfowl habitat; and protect biodiversity of the existing
native community. </font><font size=3> <br>
</font><font size=3 face="Times New Roman"><br>
The study was conducted as part of the USGS Chesapeake Bay studies, which
is providing integrated science to for effective conservation and restoration
of the Bay ecosystem. The USGS is a federal partner in the Chesapeake Bay
Program, the federal-state partnership to restore the Bay ecosystem. More
information can be found at </font><font size=3 color=#3c613e face="Times New Roman"><u>http://chesapeake.usgs.gov</u></font><font size=3>
<br>
</font><font size=3 face="Times New Roman"><br>
USGS provides science for a changing world. For more information, visit
</font><font size=3 color=#3c613e face="Times New Roman"><u>www.usgs.gov</u></font><font size=3 face="Times New Roman">.</font><font size=3>
<br>
</font><font size=3 face="Times New Roman"><br>
Subscribe to USGS News Releases via our </font><font size=3 color=#3c613e face="Times New Roman"><u>electronic
mailing list</u></font><font size=3 face="Times New Roman"> or </font><font size=3 color=#3c613e face="Times New Roman"><u>RSS</u></font><font size=3 face="Times New Roman">
feed.</font><font size=3> <br>
</font><font size=3 face="Times New Roman"><br>
**** www.usgs.gov ****</font><font size=3> <br>
</font><font size=3 face="Times New Roman"><br>
Diane Noserale<br>
Media Relations, Eastern Region<br>
U.S. Geological Survey<br>
150 National Center<br>
Reston, VA 20192<br>
phone: 703-648-4333<br>
fax: 703-648-4588</font>