Claire Corlett

Fish Food, Fish Tanks, and More
Tiny Mussels Invade Great Lakes, Threaten Fishing Industry

Tiny Mussels Invade Great Lakes, Threaten Fishing Industry

bjbjLULU JEFFREY BROWN: And next, the story
of a tiny invader doing big damage to the Great Lakes. Ash-har Quraishi of WTTW Chicago
reports. ASH-HAR QURAISHI, WTTW Chicago: It’s just after dawn in northern Wisconsin. Commercial
fisherman Dennis Hickey is getting ready to take his fishing boat out on Lake Michigan.
Hickey’s family has fished these waters for more than a century. The Great Lakes currently
support a $7 billion-a-year commercial and recreational fishing industry. MAN: Our mainstay
of our fishery here in Baileys Harbor is whitefish, Lake Michigan whitefish. ASH-HAR QURAISHI:
Today, Hickey’s lucky. He won’t be battling the elements to bring in a catch. It is unseasonably
warm on this late autumn morning. But he does have to deal with a problem that increasingly
plagues fishermen throughout the Great Lakes and threatens their livelihoods. MAN: Looks
like the hearts have quite a bit of moss and slime in them again. ASH-HAR QURAISHI: The
slime is a type of alga called Cladophora, and some scientists think its extraordinary
increase in the Great Lakes is related to recent and irreparable changes in the Marine
ecosystem. The culprit, they say, is a tiny invasive mollusk called the quagga mussel.
TOM NALEPA, Great Lakes Environmental Research Lab: To me it’s one of the worst, if not the
worst. ASH-HAR QURAISHI: Tom Nalepa is a research biologist with the Great Lakes Environmental
Research Lab at the National Oceanic and Atmospheric Administration. For the last 20 years, Nalepa
and his team have been assessing population trends and the impact of the mussel invasion
on the Great Lakes. TOM NALEPA: They find conditions very suitable and just explode
in terms of population numbers. And during the period of exponential growth, they wreak
havoc on other organisms. They take away resources, outcompete native species. ASH-HAR QURAISHI:
Henry Henderson is director of the National Resources Defense Council. HENRY HENDERSON,
National Resources Defense Council: They wreck the life that’s in there and create a new
ecosystem that is dangerous for our health and safety in fundamentally devastating ways.
You can see it happen in Lake Erie. It’s on the edge of collapse. ASH-HAR QURAISHI: Scientists
believe the quagga mussel first stowed away in the ballast water on transoceanic ships
from the Caspian Sea. The mussels made their way into the lakes when that ballast water
was purged. The tiny fingernail-sized mussels, closely related to another invasive, known
as the zebra mussel, first appeared in lake waters here in 1988. MAN: These are typical
quagga mussels in Lake Michigan. They have the striping, as zebra mussels do. They have
a little flatter shell. ASH-HAR QURAISHI: The quagga mussel is now the most pervasive
and destructive invasive species ever to enter the Great Lakes. Over the last 15 years, the
quagga population has exploded, eclipsing the zebra mussel and infecting all five of
the Great Lakes. Nalepa estimates there are now 437 trillion in Lake Michigan alone. And
the reason scientists say this dominating mussel is so destructive is that it is wiping
out critical food at the bottom of the food chain, organisms like plankton, the main food
source for a shrimp-like organism known as Diporeia. TOM NALEPA: It’s a very important
fish food organism. Hence, this has led to declines in the growth and condition of fish
populations that once depended upon Diporeia as a food source. So it’s led to a cascading
effect from one species to the other throughout the food web. ASH-HAR QURAISHI: In addition
to altering the food chain in the Great Lakes, these mussels attach to all types of surfaces,
like boats, buoys and docks. They clog water intake pipes, sometimes cutting off drinking
water supplies that require expensive remediation, which is why the financial impact from these
tiny invaders is staggering. The U.S. Fish and Wildlife Service estimates the economic
losses over the last decade at about $5 billion within the Great Lakes region alone. At the
DuSable Harbor on Chicago’s Lakeshore, operations manager Kirk Kleist pulls up a dock anchor
chain to show just us how pervasive the mussels have become in near-shore areas. KIRK KLEIST,
Chicago Harbors: They load up so much. They cause problems. ASH-HAR QURAISHI: Kleist,
who has been a diver for over three decades, says he’s seen the dramatic changes in the
lake water caused by mussel filtering. KIRK KLEIST: Thirty years ago, you had five foot
of visibility at the max. Now I have seen 40 to 60 foot of visibility. ASH-HAR QURAISHI:
But scientists say clear water in this clear is in fact a bad thing. TOM NALEPA: Water
clarity has increased two- or three-fold, just because of the ability of mussels to
filter all the particles out of the water, which they use as food. So, if you like clear
water, certainly, when you look out at Lake Michigan, you have it. But clear water also
means that there’s no food in the water for all the other organisms. ASH-HAR QURAISHI:
The other side effect of excess clarity caused by the quagga’s filtering is that it encourages
explosive algal blooms like Cladophora and toxic algae known as Microcystis. HENRY HENDERSON:
They allow for the first time in the life of the Great Lakes sunlight to pierce all
the way down to the bottom of the lake from Erie on. And that creates the ability for
toxic algae to grow, which is poisonous and a threat to our public health and safety.
ASH-HAR QURAISHI: These images taken by NOAA and the U.S. Geological Survey last month
reveal just how overwhelming the algae have become in the Great Lakes. A report published
by the National Wildlife Federation called the toxic algal bloom that infested Lake Erie’s
western basin this year and caused mass beach closings the most harmful ever recorded. MICHAEL
MURRAY, National Wildlife Federation: When the Cladophora wash up on beaches, they often
harbor problematic bacteria, including botulism, which then can negatively impact fish and
birds that consume somewhere in the food web. ASH-HAR QURAISHI: Michael Murray is a staff
scientist with the National Wildlife Federation’s Great Lakes office in Ann Arbor, Mich., and
co-authored the report. Murray says the Great Lakes are experiencing both feast and famine,
because while algae is growing in record amounts in coastal areas, there is also the formation
of nutrient deserts in offshore waters. MICHAEL MURRAY: So, the overall effect is, were still
seeing a lot of — still a nutrients in near-shore areas, major problems with algal blooms, Cladophora,
those types of problems, and then in the offshore areas, not enough nutrients and major problems
with the fisheries there. ASH-HAR QURAISHI: Because of the drastic changes in the Great
Lakes over the last two decades, commercial fishermen say they have had to adapt. Today,
they’re forced to go further and further out into the lake just to get a good catch. When
the wind blows, fisherman Dennis Hickey says the algae load up their live entrapment nets,
making it easier for fish to see and avoid. Hickey and his crew have to spend precious
time and money to pull out the nets and clean them. MAN: Well, it gets worse every year.
It’s been — the last five years, I say, it’s been increasing. ASH-HAR QURAISHI: Scrawny
fish and too much algae have become game-changers for many small commercial fishermen in the
area. MAN: The smaller fishermen just plain decided to sell out and get out of the business.
ASH-HAR QURAISHI: And the future of commercial fisheries looks bleak, because scientists
say removing the mussels from the lake is impossible. TOM NALEPA: Quagga mussels are
going to be with us now forever, I think. It’s just a matter of, at what abundance does
the population stabilize? And that’s the key. ASH-HAR QURAISHI: Scientists and activists
say that, while the focus must shift to preventing the introduction and spread of new invasive
species into the Great Lakes, the destruction under way by the quagga mussel now serves
as a painful cautionary tale. hK”7 hK”7 hK”7 urn:schemas-microsoft-com:office:smarttags
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