Jay DeLong
Olympia, WA
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New Water Flea Invades Southern Lake Michigan
URBANA, IL How could something just one centimeter in size, cause enormous
problems for Lake Michigan? Easy, when you're a water flea with no known
enemies in the area.
Researchers with the National Sea Grant College Program report that
Cercopagis pengoi, (sometimes called the fishhook flea), has recently
invaded the waters of southern Lake Michigan. Tiny, but prolific, it
reproduces rapidly, has no known predators, and can create havoc by
upsetting the lower levels of the food chain. Patrice Charlebois,
biological resources specialist for Illinois-Indiana Sea Grant noted that
although this water flea was found earlier this year in Grand Traverse Bay,
it is now posing a threat in Southern Lake Michigan.
It was first spotted in the open waters of southern Lake Michigan by Burt
Atkinson, captain of a charter boat named "Donna G," who was out with a
party off Waukegan Harbor. The captain noticed the masses (which can look
and feel like wet cotton batten) on his lines and knew they were different
from the other spiny water flea, Bythotrephes cederstroemi. Charlebois,
checked zooplankton samples collected in the same area but closer to shore
by her home institution, the Illinois Natural History Survey's Lake Michigan
Biological Station. She found them to be not only present in the sample,
but fairly abundant.
Charlebois has followed the invasion of the spiny water flea and worries
that this new species could cause even greater problems for the Lake
Michigan ecosystem. As is the case with its predecessor, this new invader
feeds on tiny aquatic organisms called zooplankton, which are an important
food source particularly for young fish. So, Cercopagis could compete for
the same food as these fish. Cercopagis also has little barbs on its tail,
which gave it the nickname, "fishhook." The barbs make it difficult for
small fish to eat them, and without a predator, the fishhook flea can
concentrate on multiplying.
"We're concerned about the potential impacts that Cercopagis will have on
the Lake Michigan foodweb. The fact that Cercopagis feeds on other
zooplankton and is not easily consumed by fish could have detrimental
impacts on all levels of the lake foodweb. The foodweb has already been
compromised by other exotics such as the spiny water flea and the zebra
mussel." Charlebois goes on to say that Cercopagis could also be a serious
threat to yellow perch. Young yellow perch rely on zooplankton as a food
resource. "If Cercopagis strikes another blow to this already battered
resource, yellow perch may feel the impact again."
So, what can be done to stop or slow down the spread of this potentially
destructive water flea in Lake Michigan and inland lakes? Boaters and
anglers can help prevent the spread of Cercopagis by observing many of the
same procedures used to prevent the spread of other exotic species. Taking
the time to do simple things like inspecting the boat and removing plants
and animals from equipment; draining the boat of all lake or river water
(including the baitbucket); dumping bait on land or in the trash, never in
the water; and rinsing the boat with a high-pressure sprayer or 104 F degree
water or allowing the boat to dry for at least five days before transporting
it to another body of water can greatly slow and even stop the spread of
Cercopagis and other exotic species.
Sea Grant is a network of 29 university-based programs involving more than
300 institutions nationwide in research, education and the transfer of
technology regarding coastal, marine and Great Lake issues. Sea Grant is
supported by the U.S. Department of Commerce's National Oceanic and
Atmospheric Administration (NOAA) in partnership with the states and private
industry.
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