Page 20 - Flathead Beacon // 12.7.16

COVER
INVASIVE SPECIES
AQUATIC INVADERS
What are mussels? How do they spread? What do they threaten? BY DILLON TABISH
A three-foot deep pile of zebra mussel shells about 50 yards long are piled up along the Lake Winnebago shoreline in
April 2012 at Highway 45 Wayside Park just north of Fond du Lac, Wisconsin. COURTESY MARK HOFFMAN | MILWAUKEE JOURNAL SENTINEL
ZEBRA AND QUAGGA MUSSELS ARE MINISCULE aquatic organisms that invade ecosystems and rapidly reproduce, causing deleterious e ects that harm native ecosystems and commercial, agricul- tural and recreational activities.
ORIGINS: Zebra mussels originated in the Black and Caspian sea drainages between Europe and Asia and were rst reported in the U.S. in the mid-1980s after ships from Europe incidentally transferred the spe- cies in ballast water into the Hudson River in New York. Quagga mussels came from Ukraine and rst invaded the U.S. in 1988, when they were discovered in Lake St. Clair between Ontario and Michigan. By 2014, they have infested rivers and lakes in 29 states, primarily by cling- ing to recreational boats and traveling
through connected river systems. LIFESPAN: Typically up to 5 years. Mussels can survive out of water for up
to 10 days in ideal conditions. REPRODUCTIVE POTENTIAL: Mus-
sels can reproduce all year but most often spawn in spring and fall. In a ve- year lifetime, a single quagga or zebra mussel will produce about ve million eggs, 100,000 of which reach adulthood. The o spring of a single mussel will in turn produce a total of half a billion adult o spring.
HOW DO THEY SPREAD? Adult mus-
sels attach to recreational boats and
equipment, such as anchors and bait
buckets, and attach to new subsurfaces,
such as docks, rocks and aquatic objects
before creating a colony. Boats that
are moored or held in a slip are much
more likely to harbor zebra and quagga
mussels than day boats. Larvae ow FWP watercraft inspection station in Ravalli. BEACON FILE PHOTO
decreased by 80 percent.
ERADICATION: Once zebra and quagga mussels
become established in a water body they are impossible to fully eradicate.
PREVENTION: Education is key. Convincing rec- reational boaters to su ciently clean their boats and equipment before transporting them to new waters is essential, according to experts. Boaters should remove all aquatic plants, animals, and mud from everything that came in contact with water; drain all water, includ- ing bilges, live-wells, cooling water from the motor; clean and dry everything that came in contact with water; dis- pose of any live bait. If mussels are seen attached to a boat or other recreational equipment, it must be decon-
taminated using more stringent guide- lines. Preventing downstream invasions is practically impossible.
THREATS
ECOLOGICAL
• As lter feeders, mussels remove food and nutrients from the water column very e ciently, leaving little or nothing for native aquatic species, including sh. They devastate native species by strip- ping the food web of plankton, which has a cascading e ect throughout the ecosystem. Lack of food has caused pop- ulations of salmon, white sh and other species to plummet.
• Zebra and quagga mussels promote water clarity by lter feeding. The clearer water allows sunlight to pene- trate to the lake bottom, creating ideal conditions for algae to grow. In this way, zebra and quagga mussels have promoted
downstream and can also be transported in water car- ried by recreational boats, trailers and other equipment. Zebra mussel larvae can be carried in boat bilge water, live wells, bait buckets, and engine cooling water sys- tems even if the boat has been in infested water for only a short time. Since the rst adult mussels were discovered in the Lake St. Clair in 1988, there are now an estimated 10 trillion mussels throughout all of the Great Lakes.
DIET: Mussels feed on small organisms called plank- ton that drift in the water. Phytoplankton and zooplank- ton form the base of the aquatic food web, providing a key nutritional source for sh. For example, since mus- sels were discovered in the Hudson, microzooplankton have declined by 70 percent and phytoplankton have
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DECEMBER 7, 2016 // FLATHEADBEACON.COM
Deb Tirmenstein, with the Flathead Basin Commission, and her dog Ismay search a boat for aquatic invasive species at an