There is an aquatic invasive species people are trying to prevent the 
spread of. It is a freshwater alga that can form blooms in rivers and 
potentially harm aquatic invertebrates. It's commonly referred to as 
"didymo" or "rock snot". I don't know of any direct effect on birds, but 
it could affect the food sources of birds that eat aquatic 
invertebrates. In Maryland, it was found at Gunpowder Falls in Baltimore 
County in the spring of 2008.

A nationwide map of where it has been found so far is posted at
http://www.vtwaterquality.org/lakes/docs/ans/lp_didnadistmap.pdf

And general information is posted at
http://en.wikipedia.org/wiki/Didymosphenia_geminata

Below is part of an email that appeared on a dragonfly listserve 
explaining control methods.

-- 
June Tveekrem
Columbia, Maryland
tweekiebird|AT|southernspreadwing.com
http://SouthernSpreadwing.com



-------- Original Message --------
Subject: 	[Odonata-l] Oregon DSA Meeting Precautions
Date: 	Fri, 25 Jul 2008 09:16
From: 	Bryan Pfeiffer <>
To: 	NEOdes <>, , 
, 


Here in Vermont and elsewhere, we are trying to prevent the spread of 
/Didymosphenia geminata/, a freshwater algae also known as "Rock Snot." 
It can bloom to form mats that carpet a stream or river bottom (and 
potentially harm odonates and other things we care about). I'm no 
expert, but it is reported that only one cell of the stuff can infect a 
new location.

In Vermont we're disinfecting our clothing and gear each time we switch 
rivers or move upstream. Detergent, bleach, soap, and very hot water can 
be effective disinfectants. Here's more information:

http://www.issg.org/database/species/ecology.asp?si=775&fr=1&sts
http://www.vtwaterquality.org/lakes/htm/ans/lp_didymo.htm
http://www.epa.gov/region8/water/didymosphenia/


Best,
Bryan Pfeiffer
-- 

Wings Environmental: www.wingsenvironmental.com
Wings Photography: www.wingsphotography.com
Vermont Bird Tours: www.vermontbirdtours.com