eggs pose lakes risk
By Story and photo Sharon Hill Star County Reporter
Thousands of tiny stowaway eggs could bring the next troublesome
invader into the Great Lakes, researchers have found.
For the first time, a University of Windsor biology student
has proved that the eggs of small invertebrates in the
holds of ships can hatch.
PhD student Sarah Bandoni, working with biologist Hugh
MacIsaac at the university's Great Lakes Institute for
Environmental Research, hatched eggs in the lab after
taking them from the bottom of freighters last year.
"These eggs can dry up, they can be boiled, frozen and
once conditions get back to ideal happy conditions, these
eggs will hatch," she said. "It's an excellent mechanism
for transplanting invasive species."
Current regulations were designed to make sure live foreign
species in ballast water weren't accidentally transported
into the Great Lakes.
Bandoni said freighters do empty ballast water before
entering the Great Lakes, but some water and sediment
is always left behind. A centimetre of water in the bottom
of a giant ship can equal tonnes of water.
Freighters can take in water from the Great Lakes once
in the lakes but when they leave, some ships will take
on cargo and dump some water. That means the eggs could
be stirred up and released or the ship could be a giant
incubator where the eggs have already been hatched. Then
live species would be dumped in the lake.
Bandoni boarded 20 ships last year to get samples of
muck and water from the holds of ships. She takes the
tiny eggs that can be microscopic to about a millimetre
in size and waits to see what will hatch.
"It's like a box of chocolates," she said borrowing a
line from Forrest Gump. "You never know what you'll get."
Mostly the 24-year-old student finds tiny invertebrates
-- animals without backbones. More research is needed
to see if any of the water contained exotic species not
already found in the Great Lakes.
In a 40-gram water sample, Bandoni said she's found as
many as 1,600 eggs of one species. Her experiments showed
as many as 90 per cent of some eggs hatched.
She even tried leaving the eggs in the dark to simulate
the hold of a ship but found they still hatched.
This year she'll focus on seeing how much salt the eggs
can take. Ships with ballasts of salt water weren't considered
a threat because regulators thought anything used to salt
water wouldn't survive in fresh water.
More than 160 invasive species from plants and fish to
tiny invertebrates have been unwittingly introduced into
the Great Lakes. Scientists want to make sure something
as problematic as the zebra mussel doesn't get in next.
Exotic species are a problem because they can be costly
to battle and can change the ecosystem of the lake. For
example, the commercial fishery could be threatened if
an invading invertebrate started competing with small
fish for food.