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

[Patricia_DeAngelis at fws.gov]

Forwarding an interesting nugget of info on this topic.


----- Forwarded by Patricia De Angelis/ARL/R9/FWS/DOI on 05/18/2007 06:20 
PM -----

Yes, but how about the "duck Alzheimer's" which appears to be associated
with hydrilla.  Also, not all scientists agree the Potomac hydrilla
infestation is so innocuous.

There are possible redeeming virtues to a lot of things.  The dose makes
the poison is a statement sometimes heard from toxicology.

Volume 20 | Issue 5 | Page 59  | Reprints | Issue Contents

1 comment
Comment on this article
-------------------------------------------------------------------------

COLUMN
By Jack Woodall
Space Invaders Are Here
Guess what? They're little and green!



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


I wonder why people began imagining that space invaders were green. 
Perhaps
it was because humans had already appropriated most of the other colors:
black, white, khaki, red, yellow, and blue. The ancient Brits painted 
their
naked bodies blue with woad, so they say, but that was before football 
fans
started painting themselves in the colors of their teams. Now you can see
green people rooting for Brazil, but they have a yellow stripe also.


Be that as it may, the color of the invaders I am talking about is due to
chlorophyll; they are plants, not humanoids, and they do not come from
outer space, but from one part of the globe to invade the space of 
another.
Classic examples are the Nile cabbage (Pistia stratiotes), responsible for
blocking navigation over long stretches of the White Nile in the southern
Sudan, has turned up in the Amazon. In revenge, the South American water
hyacinth (Eichornia crassipes) - with its lilac flowers and gas-filled
bladders that give buoyancy to drift down rivers and foul the beaches of
Rio de Janeiro after torrential rains - has invaded the Nile.


I want to report on two much more insidious green threats, with the
appropriately alien names of kudzu (Pueraria montana var. lobata) and
hydrilla (Hydrilla verticillata). Kudzu is a broad-leaved Asian vine,
imported to the United States a century ago by immigrant farmers to grow 
as
cheap fodder for their cattle. It has spread out of control across 
enormous
areas of the country, overgrowing and strangling every tree, bush, plant,
or even object in its path (see the images at www.jjanthony.com/kudzu ).


The damage does not stop there. Kudzu is host to a serious crop pest. The
fungus that causes soybean rust (Phakopsora pachyrhizi) was first
identified in Japan in 1902 and took a century to cross the Pacific,
reaching South America in 2000. In 2004 Hurricane Ivan picked up spores
from there and dropped them over nine southern states of the United 
States.
Once there, they not only infested soybean fields, but also found a
congenial alternate host: kudzu. As a result, no matter how much fungicide
farmers spread on their soybean fields, the rust will be hiding in kudzu
leaves ready to make a comeback. But in a nice twist, weed-control groups
are growing the fungus that causes wheat rust, another crop pest; the
fungus is rubbed into cuts in the kudzu stems to kill the plant.


The other alien threat was discovered when American bald eagles 
(Haliacetus
leucocephalus) and coots (Fulica americana) began to flop around in 
circles
and show brain damage - I have no idea why it wasn't called mad bird
disease - and to die in numbers on some Arkansas lakes. Between 1994 and
2002, at least 100 eagles and thousands of coots died at 11 lakes between
North Carolina and Texas. The cause was traced to a neurotoxin in the
water. But what was the source of the poison, and why did it affect mostly
those two species?


It turns out that the neurotoxin is connected to hydrilla, an invasive
species of water plant. Hydrilla was imported into the United States in 
the
1960s from its native Africa, Australia, and parts of Asia by the aquarium
industry to prettify fish tanks. Inevitably, it escaped when aquarium
owners emptied their tanks into the environment, and it now totally covers
the surface of many lakes in Arkansas, Florida, and other states — 
10,000
acres in South Carolina alone.


The damage does not stop there. Hydrilla attracts a blue-green
cyanobacterium, of a species previously unrecorded in the United States,
which flourishes on its slender fronds. Cyanobacteria as a class produce
deadly toxins - not, I hasten to add, out of pure malice, but as an
unintended consequence of getting rid of unwanted products of their
metabolism. Vegetarian water birds such as coots and many ducks feed on 
the
plant, sicken from the toxin and die. Eagles find the sick birds easy 
prey,
feed on them, and die in their turn - a classic food-chain disaster just
like that which led to the banning of DDT.


So beware of little green alien invaders. Chop down the kudzu on your land
and when you empty your fish tanks, bury or burn the plants.


Jack Woodall is director of the Nucleus for the Investigation of Emerging
Infectious Diseases in the Institute of Medical Biochemistry at the 
Federal
University of Rio de Janeiro, Brazil.

jwoodall at the-scientist.com




Comment on this article


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


comment:
Space Invaders Are Here
by kate austin

[Comment posted 2007-05-17 19:18:02]


Kudzu covers over seven million acres in the South. Why not harvest it and
use it to produce cellulosic bioethanol for fuel? No need for chemical
fertilizers or arable land needed for crops.



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



Alan V. Tasker, Ph.D.
National Noxious Weed Program Manager

USDA  Animal & Plant Health Inspection Service
Plant Protection & Quarantine
Emergency and Domestic Programs
Invasive Species & Pest Management

       (301) 734-5708
Fax (301) 734-8584


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plantconservation.org/pipermail/apwg_lists.plantconservation.org/attachments/20070518/1d5218bf/attachment.html>