New ballast water rules target invasive species  Environment
Stephanie Hemphill · ·   1. Listen ballastwaterrules      Sep
19, 2008  Discharging ballast water  Every year, hundreds of
ships slide under the Aerial Lift Bridge into the port of
Duluth. They come from the oceans of Europe and Africa. They
also come from Canada, and other ports on the Great Lakes.
These ships carry iron ore, grain, windmills, and sometimes --
like a giant floating aquarium -- they transport fish and other
critters that don't belong in Lake Superior.  Researchers have
found 88 non-native species in Lake Superior. With no natural
predators, many of them thrive in their new home and quickly
out-compete native species, threatening entire populations and
throwing entire ecosystems out of balance. For example, lamprey
and zebra mussels have changed the Lake Superior ecosystem
forever.  Nearly half of those invaders arrived in ships --
often in the ballast water that ships carry to balance their
loads.  As many as nine billion gallons o