ZEBRA MUSSELS: “Poster child” of biological invasions Prepared by Dick Sternberg on behalf of: • Kandiyohi County •Middle Fork Crow River Watershed District •Kandiyohi County Lakes Association (a coalition of 17 lakes) •Green Lake Property Owners Association
What are ZebraMussels & Why are they a Problem?•Zebra mussels are smallfreshwater mollusks (¼ to1½ inches long) named forthe striped pattern oftheir shells.•Native to Black and Caspian sea drainages in Eurasia•Brought to North America in the ballast waters of trans-Atlanticfreighters in the late 1980s•Attach to underwater objects with theirbyssal threads•Filter the water to remove plankton thatwould otherwise provide food for fish andother aquatic life
•May reach a density of 700,000/sq. meter•They spread extremely rapidly; within 2 years of the firstGreat Lakes sighting, they found their way into all of theGreat Lakes.•As more and more waters become infested, the rate ofspread will increase, as appears to be happening in Minnesota.•Once zebra mussels invade a body of water, there is no knownmethod of control or containment.•The only solution: KEEP THEM OUT!!!
Quagga vs. Zebra Mussels Quagga mussel Zebra musselQuagga named after an extinct Quaggas inhabit a greater range ofAfrican zebra species depths. Found in water as deep as 500Quaggas tend to be slightly larger feet; zebras rarely deeper than 75 feet.with a broader shell Quaggas found in MN waters of theRidge on quagga’s shell not as Mississippi River and in Duluth-sharp as Zebra’s Superior harbor of Lake SuperiorHinge area of quagga may lack They have displaced zebra musselsstripes. in Lake Michigan and other areas ofQuaggas can tolerate colder water the Gr. Lakes, quickly becoming far more abundant than zebras ever were.and lower oxygen levels than zebras.Consequently, quaggas feed Quaggas pose athroughout the year, not just in warmwater periods, so they filter even serious threatmore food organisms from the water. to MN lakes
Reproduction•Extremely prolific - an adult female releases up to a million eggs ina year and has a life span of 2-5 years.•The larval form, called veligers, are microscopic in size and enablethe species to spread quickly by drifting downstream with thecurrent or being transported overland by trailered watercraft.•Veligers float freely forseveral weeks beforesettling onto underwaterobjects where they cangrow and anchorthemselves with theirbyssal threads.•They may anchorthemselves to adult zebramussels, leading to therapid formation of densecolonies. Juvenile zebra mussels attached to adults
Impacts •Byssal threads secrete a powerful glue, enabling the mussels to form dense colonies on rocks, metal, plastic, concrete, pipes, ropes, boats, motors and practically any other submerged object.Before zms After zms On boats and motors On inside of pipe On stick On golf ball On remains of beer can
•Zebra mussels also attachthemselves to living things, liketurtles, crayfish and native clams.In some infested waters, nativeclams have been nearly eliminatedby encrusting of their shells.•Zebra mussels attach themselvesto aquatic plants, which are oftentransported on trailered boats. ZMs encrusting crayfish and native clam ZMs clinging to aquatic plants EWM draped over boat trailer – Bailey’s Harbor, Lake Michigan …. NEXT STOP??
•Dead and dying zebra mussels wash up on beaches, sometimes creating windrows more than a foot deep. •The decaying mussels emit a foul odor and the razor-sharp edges of their shells make footwear a must when walking the beach.Presque Isle State Park – Lake Erie
•Notorious for theirbiofouling capabilities,zebra mussels colonizewater supply pipes anddebris screens of powerplants, public water Clogged water-supply pipes Encrusted debris screentreatment plants, andindustrial facilities.•They constrict waterflow, thereby reducingthe intake in heatexchangers, condensers,fire-fighting equipment,and air-conditioning and Zebra mussels scraped from Lock & Dam #7 nearcooling systems. LaCrescent, Minnesota, 2001•They also encrust navigational buoys, pilings, docks, piers and locksand dams.•Continued attachment of zebra mussels can cause deterioration ofwooden, concrete and even steel objects, affecting its structuralintegrity, so periodic scraping or chemical treatment is necessary.
•Zebra mussels are filter feeders, sucking water in through the incurrent siphon, removing the digestible organic matter and then expelling much clearer water through the excurrent siphon. •Ejected particles are bound with mucus, forming “pseudofeces” which encrusts the bottom and displaces native bottom fauna.Incurrentsiphon Excurrent siphon
•Clearer water meansdeeper light penetration,promoting growth ofaquatic plants andfilamentous algae atgreater depths.•The plants and algae maybreak free, foulingshorelines and beaches. Heavy weed mat along Lake Erie shorelineDead ZMs tend to collectin the decaying vegetation,making a bad odor worse.•Dense algae blooms maydevelop as a result of ZMsrejecting blue-green algaewhile consuming greenalgae and other “good”algae that feed on it. Blue-green algae can be toxic to wildlife and pets
•Dead algae sinks to the bottom,promoting growth of a toxicstrain of botulism.•ZMs consume the poisonousalgae, but it does not affectthem. Gobies (invasive baitfish)then eat the toxic ZMs andbecome paralyzed.•The helpless baitfish are an easytarget for fish-eating birds,which themselves become Michigan DNR wildlife biologist examining deadparalyzed and drown. loons collected in the Great Lakes region.•Since 1999, 75,000 fish-eating birds, including 9,000 loons, have beenkilled by ZM-induced avian botulism in the Great Lakes area.•Zebra mussels “bioaccumulate” pollutants in their tissues by as muchas 300,000 times. The pollutants continue to biomagnify as they arepassed up the food chain and eaten by higher-level predators includingfish which may in turn be eaten by humans.
Impacts on Fish & Fishing•Zebra/quagga mussels filter outthe plankton that baitfish,juvenile gamefish and some adultgamefish need for food.•The water becomes clearer, butnot cleaner.•Because plankton are at thebottom of the food chain, overall A blanket of zebra mussels on the bottom meansfish productivity is reduced. clearer water but less food for fish•Dim-light feeders like walleyesgenerally go deeper and do moreof their feeding at night.•Pelagic (open-water) feederslike salmon can spot lures at agreater distance, so angler catchrates may stay the same or evenincrease, masking a populationdecline. Walleyes have better dim-light vision than their prey, so they often feed after dark in clear waters
Lake Michigan Estimated Example: Biomass of Baitfish in•Total poundage of baitfish L. Michigandropped from 450,000 tonsin 1989 to 30,000 tons(a record low) in 2008.•Alewives, the major foodfor salmon, declined from140,000 tons in 1973 to2,000 tons in 2008.•The average weight of L. Michigan chinook salmon has droppedabout 25% because of the alewife shortage.
•Diporeia, tiny shrimplikeamphipods that are themajor food source forwhitefish and many speciesof baitfish, declined by95% from 1994 to 2005. Diporeia The commercial catch of L. Michigan whitefish has declined by 70% since the mid-1990s•The average weight of a 7-year-old Lake Michigan whitefish droppedfrom more than 5 pounds in 1988 to barely a pound in 2008. Thedecline is blamed on the diporeia shortage.•The recent quagga mussel explosion has worsened the food shortage.•Clearer water resulting from the mussel explosion enables predatorfish to see baitfish at greater distances, increasing their predatoryadvantage and further reducing baitfish populations.
Lake Erie walleye population continues to sink;fishermen can comment at open housesBy Darcy Egan, Cleveland Plain DealerAugust 28, 2009Lake Eries schools of walleye may be heading for crisis management, and Ohiofishermen can give the Division of Wildlife their views Saturday, Aug. 29 on how tobest manage Ohios favorite fish at open houses held around the state. The annualopen houses are designed to bring sportsmen and wildlife experts together to discusswildlife issues. They are from noon to 3 p.m. at the Division of Wildlife district offices,including the northeast Ohio office at 912 Portage Lakes Dr., Akron. A special openhouse for walleye fishermen is at the Ottawa County Visitors Center on Rt. 53, justnorth of Rt. 2, in Port Clinton.The walleye population has perilously slumped since a bonanza hatch in 2003, andthe 2009 spawning season doesnt look promising. If the Lake Erie Committee of theGreat Lakes Fishery Commission estimates the lakewide population has slippedbelow 15 million walleye, it will call for special crisis management at its annualmeeting on March 22-26, 2010 in Windsor, Ontario. The result will be lower daily baglimits for Ohio anglers and less walleye for Ontario commercial netters, the two majorplayers in Lake Eries walleye harvest.
Economic Impacts Where do ya•U.S. Congressional researchers wanna start scraping,estimated ZM infestations cost Joe?U.S. businesses, industries andcommunities $5 billion from1993-1999.•The cost to the power industryalone was $3.1 billion.•Kandiyohi Co. gets 20% of itspower from Missouri River powerplants which, if they becomeinfested, could lead to higher Quagga mussel infestation of hydroelectric damselectric rates. in the West is a multi-billion dollar problem•These estimates came before ZM infestations outside the Great Lakesarea. Taking into account current levels of infestation, including quaggamussel infestations in the Great Lakes and the West, those costs may now bedouble.•Property values on ZM infested lakes could plummet, depending on locationand availability of property on nearby uninfested lakes.
•Attached mussels increase dragon the bottom of watercraft,reducing speed, wasting fuel, andrequiring scraping and repaintingthe watercraft’s hull.•Boat engines may be damaged byoverheating due to ZMs blockingcooling water intakes.•Anti-fouling paint will helpprevent ZM attachment, but asingle application may cost from afew hundred to more than $1,000,depending on boat size. Heavy ZM buildup on hull greatly increases drag•Historic, sunken ships and artifacts may become completely obscured by ZMcolonies growing on them.• Swimming beaches will require constant clean-up to remove sharp, bacteria-laced mussel shells. Some Great Lakes swimming beaches have been closed asa result of ZM-induced E. Coli outbreaks.•Aquatic communities impacted by zebra/quagga mussels are changing so fastthat biologists are finding it difficult to predict the long-term impacts ongamefish. But it is safe to say that less fish food means less fish, and thatwill surely reduce fishing opportunities and impact tourism.
Possible Sources of ZM Contamination• Boats/motors/trailers, including canoes, kayaks, jet skis, sailboats and all other types of watercraft• Anchors, anchor ropes, life jackets, dock lines• Water skis, inflatable rafts and tubes and tow ropes• Sandals and other footwear used when wading or walking a beach• Bait containers, lake water in bait containers• Fishing/hunting equipment like waders, landing nets, decoys• Dock moving/installation equipment• Weed-harvesting equipment• Nets, traps and other aquaculture equipment (state/federal/private)• Sampling equipment used by natural resource agencies• Float planes (sightseeing rides)• Pets that have been in the water• Wetsuits, tanks, regulators and other scuba equipment
The Biggest Threats•Boats with complex plumbingsystems, such as multiple livewells. These boats may bedifficult to decontaminatebecause hot water must beforced through all of the hoses,pumps and valves to kill the This live-well diagram illustrates the complexveligers. plumbing systems found in many fishing boats•Large boats left in slips or tied up to docks for long periods of time. loThese watercraft are likely to collect adult ZMs which can infest otherbodies of water should the boat be trailered.•Boats that are used often and on many different waters.Not only is the risk of exposure higher, the drying period between uses isnot long enough to kill veligers.•Boats, boat lifts or other pieces of equipment that have been used oninfested waters and then purchased by buyers on uninfested waters.
MN Zebra MusselDistribution - Nov. 2009•To date, Zebra musselshave been found in about 50Minnesota lakes, rivers andwetlands.•There have been twoinfestations within 60 milesof Kandiyohi County, one inLake Le Homme Dieu(Douglas County) and Kandiyohianother below the Sartell County, MNDam on the Mississippi River(Stearns County).•Calcium, a key indicator of ZM colonization potential, is present inKandiyohi County waters at high levels. All other important waterquality parameters appear to be suitable for ZM survival.•Kandiyohi County is at high risk for ZM infestations.
Minnesota’s ZM Program•“Stop AquaticHitchhikers” is theprogram’s motto.•Education is the main MNDNR has partnered with local and federal agencies totheme. place 31 billboards along MN highways•Besides the educational tools mentioned earlier, MNDNR conductspublic awareness events and provides speakers to lake associationsand other interested groups.•About 50,000 boat inspections are conducted annually in an attemptto find any aquatic hitchhikers (not just zebra mussels).•Despite these efforts, the spread of zebra mussels has accelerated. “ This year saw the largest increase in infested waters for the state since the first occurrence in the state.” (MNDNR
Why has the Spread Accelerated in MN?Infestation of large, heavily used lakes like Mille Lacs, Pelican and theLe Homme Dieu chain has exposed an increasing number of lakes toZMs because of transport on trailered boats.Excerpts from MNDNR 2009 AIS Report:•Dive surveys in Mille Lacs Lake by DNR Fisheries and Ecological Resourcesstaff found a ten-fold increase in zebra mussels over numbers from 2008.• Veliger numbers were significantly higher than the previous years. Allplankton samples collected in August and September had veligers present,indicating widespread reproduction in the lake.•All data suggest that the zebra mussel population in Mille Lacs hasexpanded enormously and is reproducing and settling at a high rate.
•Most inspections areconducted by DNR internswithout thorough trainingor proper equipment forfinding zebra mussels,especially the microscopicveligers.•With 900,000 licensedboats in MN and anunknown number of out-of-state boats, less than DNR-trained intern checking for AIS.5% are inspected.•Inspectors are not authorized to check live wells, internal plumbingor interior compartments.•If an inspector finds zebra mussels on a boat, the operator isinstructed to clean the boat off prior to launching or leaving anaccess site.•But rarely are there any facilities, such as hot-water pressurewashers, available for decontaminating boats. The lack of the properdecontamination equipment is a serious problem.
• Boaters can be fined up to $500 for transporting invasive species inMN, but such fines are rarely imposed.• Inspectors have no enforcement authority, so they must contact aconservation officer or licensed peace officer to issue a citation.• 59 citations were written in 2009 for all AIS violations.• Boats can enter from other states without a border inspection.•From DNR 2009 AIS Report : Future needs for management of zebra mussels: • Continue monitoring zebra mussel populations in various Minnesota waters. • Continue the Volunteer Zebra Mussel Monitoring Program. Taking into account the level of monitoring and the large number of lakes at risk in MN, it’s clear that a more aggressive approach is needed.
Some will argue that zebra mussels cannot be stopped, so there is no point in spending millions of dollars on prevention and containment… Others say that zebra mussels aren’t so bad – after all they clear up the water so why worry? But unless we want our lake bottoms to look like this, we have to stop the spread right now, and that means investing millions to save billions. We do not want to find ourselves asking the question:Why didn’t someone do something toprevent this when we had a chance?