The beach looks beautiful... until you stumble on dead birds and fish killed by Type E botulism. (Photo by Rebecca Williams)
A deadly toxin is spreading across
the Great Lakes, killing fish and birds.
Rebecca Williams reports scientists are
trying to put the puzzle together as quickly
as they can:
Transcript
A deadly toxin is spreading across
the Great Lakes, killing fish and birds.
Rebecca Williams reports scientists are
trying to put the puzzle together as quickly
as they can:
(sound of waves lapping the beach)
It’s one of those perfect beach days. Not too hot, not too crowded. Everything’s
just right.
Unless you don’t like rotting fish and dead birds full of maggots.
Hunter Brower is hanging out at this Lake Michigan beach. He says he’s seen a
lot of dead gulls here in recent years.
“It’s disgusting. We’re out here to enjoy our time and it’s just not right.”
The birds and fish are being killed by Type E botulism. Basically, it’s food
poisoning. For about a decade now, botulism has been killing huge numbers of
birds in the Great Lakes.
We’re talking about more than 75,000 birds – and scientists think that’s probably
a very conservative estimate. That’s because birds could be dying and not
reaching the shore. And it’s very hard to know how many fish are getting killed.
They’re harder to diagnose.
“It’s really one of nature’s most potent toxins.”
Mark Breederland is with Michigan SeaGrant. He says some studies show the
toxin can paralyze fish.
“They can actually lose their orientation and be bobbing up and down vertically
and that would be easy pickin’s if you’re a loon.”
Loons and other birds eat those poisoned fish, or, even grosser, they’ll eat the
maggots in dead birds on the beach, and get sick. The toxin can make birds lose
control of their neck muscles. Their heads fall in the water and they drown.
Beaches full of dead fish and birds aren’t great for tourism. But scientists are
more worried about what this means for endangered species – from the giant lake
sturgeon to the tiny piping plover.
Mark Breederland says they’re also worried about the thousands of migratory
birds that get killed on their way south in the fall.
“They’re just driving down their migratory highway, pulling over for a rest stop to
get something to eat, and that’s their last and final resting spot.”
So scientists are trying to pin down what’s going on.
There’s one main hypothesis. It involves some nasty little critters: invasive zebra
mussels and their cousins, the quaggas. They got into the lakes in the ballast
water of foreign ships.
Both mussels suck in lake water and filter it. They’ve made the lakes a lot clearer
than they used to be.
The clearer water means more sunlight can reach the lake bottom, and that
kick-starts algae growth. When the algae die, it sucks oxygen out of the water.
And, all of that is perfect for a bacterium that produces the botulism toxin to go forth
and multiply.
Okay, now, remember those pesky mussels? Scientists suspect they can take in
the toxin but they’re not affected by it. But fish that eat the mussels get sick.
One fish in particular loves to eat mussels. It’s the invasive round goby. And
there are lots and lots of gobies in the Lakes. That could mean lots of poisoned
snacks for bigger fish and birds.
Researchers have a bad feeling about all this, and they’re trying to confirm their
hunches.
(sound of boat engine starting up)
Brenda Moraska LaFrancois is headed out on Lake Michigan to investigate. She’s
part of a team that’s collecting samples from the lake bottom.
She says this is a tough mystery to unravel.
“These are really complicated systems and unfortunately they’re continuing to
change.”
As soon as scientists think they have a handle on what’s going on, some new
invader gets in and messes everything up again. So it’s really hard to know what
could be done to stop the outbreaks.
The experts say, if you go to the beach, it’s safe to swim. But you shouldn’t eat any
fish or waterfowl that seem sick.
Your local wildlife managers might tell you: don’t touch it, but get something to
bury the dead animal down in the sand, so other birds won’t feed on it and spread the
toxin.
For The Environment Report, I’m Rebecca Williams.