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Aquatic Invasive Species in Iowa:Current and Emerging Threats
Kim BogenschutzIowa Department of Natural ResourcesAquatic Invasive Species Program Coordinator
What are Aquatic Invasive Species?
Aquatic invasive species are nonnative wildlife or plant species that have been determined by the Department to pose a significant threat to the aquatic resources or water infrastructure of the state.
Invasive Aquatic Plants
• Eurasian watermilfoil• Brittle Naiad• Curlyleaf Pondweed• Purple Loosestrife• Flowering Rush• Salt Cedar• Federal Aquatic Noxious Weeds
Eurasian Watermilfoil
• First identified in Iowa in 1993• 12-21 pairs of leaflets• Fragile appearance - leaves
collapse against stem when removed from water
• Reproduces primarily by fragmentation
Eurasian Watermilfoil Infestations in Iowa through 2016
Anderson Prairie Pond
Sportsman Recreation Area PondSiems Park Ponds
St. Benedicts Pits
Crystal LakeRudd Lake
Airport Lake
Beeds Lake
Wilson Grove PondSweet Marsh
Mitchell Avenue Pit
South Prairie LakeGrundy County Lake
Koutny PondSnyder Bend
Walnut Acres Campground Pond
Horseshoe Pond
Maxwell Pond
Camp Sunnyside Pond
Mississippi River
Red Rock Pond
Mile Hill LakeKeg Creek Lake
Scott Lakes
Walnut Creek Marsh
Ottumwa Pond
Plainfield Lake
Meier Wildlife Refuge
Fogle Lake
Floyd CCB Pond
Percival Lake
Pinky’s Glen
Mill Creek Lake
Jennett Pond
Carter Lake
Blue Pit
Brushy Creek Lake
Brittle Naiad
• First identified in Iowa in 2003• Stems highly branched, crowded terminal nodes• Leaves opposite, recurved,prominent marginal teeth• Reproduces by fragmentation and seeds
Brittle Naiad Infestations in Iowa through 2016
Don Williams Lake
Arrowhead, Black Hawk Slough
Slip Bluff LakeNiine Eagles Lake
Prairie Rose Lake
Springbrook Lake
Pine Lakes
Central Park Lake
Curlyleaf Pondweed
• First identified in Iowa in 1930’s• Reddish-green, wavy, alternate
leaves with finely toothed margins
• Reproduces through turions(hard, burr-like buds)
• Grows early in spring and generally dies by mid-July
Iowa Counties with Curlyleaf Pondweed Infestations
Snyder Bend
Purple Loosestrife
• Unknown when first identified in Iowa• Plant height 2-7 feet• Linear leaves with smooth edges,
usually opposite• Long spikes of purple or magenta
flowers with 5-6 petals• Flowers in July and August• Reproduces by seeds and rhizomes
Iowa Counties with Purple Loosestrife Infestations
Flowering Rush
• First observed in Iowa in 2009• Umbrella-shaped clusters of
whitish pink flowers with 3 petals• Green triangular stems• Erect emergent leaves, tips may
spirally twist• Reproduces by seeds, rhizomes,
and bulbils (small bulbs)
Salt Cedar• First Identified in Iowa in 2000• Deciduous shrubs or trees 10-15 feet tall• Spikes of pink or white flowers at branch tips• Gray-green, scale-like leaves about 1/16 inch long• Brownish purple, ridged, furrowed bark on older
plants• Reproduces by seeds and resprouting
Brazilian Waterweed• First identified in Iowa in 2017• Whorls of 4 or more spear-shaped leaves with
minutely-toothed edges• Usually rooted but can be free-floating• Only male plants in U.S.; reproduces by
fragmentation
Hydrilla
• Identified in Missouri in 2012• Long stems that branch at the
surface• Whorls of 4 or more spear-shaped
leaves with coarse teeth along the edges and midrib
• Reproduces primarily by fragmentation, turions, and tubers
Starry Stonewort
• Identified in Minnesota in 2015• Stems bright green and smooth• Star-shaped white bulbils attached to
clear, root-like filaments• Length of branchlets highly variable
on a single plant• Only male plants in U.S.; reproduces
by fragmentation and bulbils
Invasive Aquatic Plant Impacts• Displace native aquatic and riparian vegetation
and wildlife habitat • Dense growth restricts boating, water-skiing,
fishing, and other recreation• Typically spread from lake to lake by watercraft
and/or trailers
Invasive Aquatic PlantControl and Management
• Prevention• Physical
– harvest– dewatering– water dyes
• Chemical– fluridone, diquat,
triclopyr• Biological
Invasive Aquatic Invertebrates
• Zebra Mussel*• Quagga Mussel*• Rusty Crayfish*• Fishhook Waterflea• New Zealand Mudsnail• Spiny Water Flea• Federal Injurious Aquatic Wildlife
*Located in Iowa
Zebra Mussel
• First identified in Iowa in 1992• Yellow and/or brown D-shaped
shells up to 2 inches long with alternating light and dark bands
• Usually grow in clusters containing numerous individuals
• Each female can produce up to 1 million eggs; veligers are free swimming and stay in the water column for 2-4 weeks
Zebra Mussel Distribution in Iowa through 2016
Clear LakeRudd Lake
Bluebill Lake
Lake Delhi
Lake Cornelia
Blue Pit
Lake Macbride
Brushy Creek Lake
Clear Lake Zebra Mussel Population Growth
2006 2007 2008Sites w/ ZM 5 10 10No. adult ZM 1 210 10,000’sNo. juvenile ZM 12 1,000’s TNC% structures w/ ZM 5 >90 100
Zebra Mussels in Lake Rathbun?
Zebra Mussel Impacts
• Clog pipes• Hamper boating• Foul beaches• Kill native mussels, plants,
crayfish, etc.• Compete with small fish
and native mussels for food
Zebra Mussel Control and Management
• Prevention• Mechanical/Physical
– dewatering• Chemical
– molluscides– chlorine, ozone, radiation– potassium chloride (potash)– copper sulfate
• Biological– Zequanox– micromatrix/biobullets
Rusty Crayfish• First reported in Iowa in 1979 but may have been
misidentified; confirmed in 2002 • Grayish-green body usually 3-5 inches long with pair
of rust-colored spots on carapace (back)• Large, black-tipped claws with oval gap when closed• Displace native species, reduce native plant
abundance and diversity, hybridize with native crayfish
Invasive Aquatic Fish
• Bighead Carp*• Silver Carp*• Black Carp• White Perch* • Round Goby• Rudd• Ruffe• Federal Injurious Aquatic Wildlife
*Located in Iowa
Bighead and Silver Carp
• First identified in Iowa in 1995• Deep, laterally-compressed body with tiny scales• Large mouth without teeth• Eyes far forward and project downward• Reproduction only known from rivers
Asian Carp Distribution in Iowa through 2016
Bighead and Silver Carp Impacts
• Compete with native filter-feeders (paddlefish, buffalo, mussels, larval fish)
• Disrupt commercial fishing for more profitable species
• Disrupt water recreation
Asian Carp Control and Management
• Prevention• Barriers
– dams– electric
• Experimental techniques– carbon dioxide– complex sound– micromatrix piscicide delivery– pheromones
• Harvest
Iowa Great Lakes Asian Carp Barrier
Black Carp
• First identified in the Mississippi River in Illinois and Missouri in 2004
• Long narrow body, brown to black along the spine fading to white along the belly with a gold sheen
• Large, dark-edged scales• Reproduction only known from rivers• May reduce native mussel and snail populations
Northern Snakehead• Identified in White River (Arkansas) in 2008 and
Mississippi River (Mississippi) in 2017• Torpedo-shaped body up to 33 inches, tan body
with dark brown mottling• Long dorsal and anal fins• Can survive days out of water; overland migration
possible by juveniles• May compete with native species for food and
habitat
Aquatic Invasive Species Program Activities
• Public Outreach• Vegetation and Zebra Mussel Surveys• Monitoring of Asian Carp Populations• Control and Management of Aquatic Invasive
Species Infestations• Watercraft Inspections
AIS Program Funding and Staff
• $650,000 budget - boat registration fees (increased revenues from Boat Registration Act of 2005 is split between boating safety and AIS), federal grant, Fish and Game Protection Fund (Trust Fund)
• 1 Full-time Natural Resources Biologist• 1 Full-time Natural Resources Technician• Up to 20 Seasonal Aides
Public Outreach Methods
Monitoring the Spread of AIS
• Vegetation Surveys• Zebra Mussel Surveys
– Hard structure surveys– Settlement samplers– Veliger sampling
• Bighead and Silver Carp Distribution
Invasive Plant Surveys
Zebra Mussel Monitoring
Asian Carp Surveys
Iowa Watercraft Inspection Results
Knowledge of 2001 2016Invasive species 51% 92%Eurasian watermilfoil 46% 68%Zebra mussels 50% 93%Asian carp na 93%Brittle naiad na 40%AIS law 25% 90%
Boats with Species Attached(8,209 Boats Inspected in 2016)
None 7,615 (93%)Eurasian watermilfoil 4Brittle naiad 2Zebra mussels 3Curlyleaf pondweed 160Vegetation/other 426
Preventing the Spread of AIS• CLEAN any plants, animals, or mud from boat and
equipment before leaving a waterbody.• DRAIN water from all equipment (motor, live well, bilge,
transom well, bait bucket) before leaving a waterbody.• DRY anything that comes into contact with water (boats,
trailers, equipment, boots, dogs). Before transporting to another waterbody either:– Spray boat and equipment with hot, high-pressure water;
or– Dry boat and equipment for at least 5 days.
• Never release plants, fish, or animals into a waterbody unless they came out of that waterbody and empty unwanted bait in the trash.
www.iowadnr.gov/ais515-432-2823
Aquatic Invasive Species Law(Iowa Code 456A.37)
• Aquatic invasive species (AIS) are identified and designated by the Iowa DNR
• Prohibitions:– A person shall not transport on a public road or
place into waters of the state any water-related equipment that has an AIS or aquatic plant attached or within ($500 fine)
– A person shall drain all water from water-related equipment when leaving waters of the state. Drain plugs, valves, etc. shall be removed or opened while transporting water-related equipment ($75 fine)
Aquatic Invasive Rule(Iowa Administrative Code 571 Chapter 90)
• Rule lists prohibited aquatic invasive species• “A person shall not possess, introduce, import,
purchase, sell, barter, propagate, or transport AIS in any form in this state” with exceptions including:– disposal as part of harvest or control– transported in a sealed container to be identified– caught by angler and returned to water or
immediately killed