[APWG] Fw: USGS News Release: Exotic Hydrilla Benefits ChesapeakeBay?s Ecosystem

[Marc Imlay]

How well has the exotic Hydrilla done is less polluted areas with less
nitrogen nutrients?  In those reaches, which had more natives species to
start with, did Hydrilla out compete the natives? What about the
neurological impact on bald eagles with the associated exotic
microorganisms? Marc 

 

Marc Imlay, PhD 

Conservation biologist, Anacostia Watershed Society 

(301-699-6204, 301-283-0808 301-442-5657 cell)

Board member of the Mid-Atlantic Exotic Pest Plant Council, 

Hui o Laka at Kokee State Park, Hawaii 

Vice president of the Maryland Native Plant Society, 

Chair of the Biodiversity and Habitat Stewardship Committee 

for the Maryland Chapter of the Sierra Club.

 

 

 

  _____  

From: apwg-bounces at lists.plantconservation.org
[mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of
Patricia_DeAngelis at fws.gov
Sent: Friday, May 18, 2007 2:33 PM
To: apwg at lists.plantconservation.org
Subject: [APWG] Fw: USGS News Release: Exotic Hydrilla Benefits
ChesapeakeBay?s Ecosystem

 


Forwarding this news release with an interesting twist on exotic aquatic
species.... 

Patricia S. De Angelis, Ph.D.
Botanist - Division of Scientific Authority
Chair - Plant Conservation Alliance - Medicinal Plant Working Group
US Fish & Wildlife Service
4401 N. Fairfax Dr., Suite 750
Arlington, VA  22203
703-358-1708 x1753
FAX: 703-358-2276
Working for the conservation and sustainable use of our green natural
resources.
<www.nps.gov/plants/medicinal>

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

U.S. Department of the Interior 
U.S. Geological Survey 

News Release 

May 18, 2007        Nancy Rybicki        703-648-5728
nrybicki at usgs.gov 

        Jurate Landwehr        703-648-5893        jmlandwe at usgs.gov 


Exotic Hydrilla Benefits Chesapeake Bay's Ecosystem 

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 ASLO: Limnology and
Oceanography, v 52, pages 1195-1207. 

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 Limnology and Oceanography. 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. 

"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.   

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.   

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.   

"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. 

"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."   

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.   

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 http://chesapeake.usgs.gov 

USGS provides science for a changing world. For more information, visit
www.usgs.gov. 

Subscribe to USGS News Releases via our electronic mailing list or RSS feed.


**** www.usgs.gov **** 

Diane Noserale
Media Relations, Eastern Region
U.S. Geological Survey
150 National Center
Reston, VA  20192
phone:  703-648-4333
fax:  703-648-4588 

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