Risk Assessment For Invasive Aquatic Plants Reuben Keller & David Lodge Presentation to: Invasive Plant Species Assessment Working Group Indianapolis, Nov. 30, 2004
Overview 1. Invasive aquatic plants in Indiana • • Impacts Sources Regulations Reducing the impacts 2. Species available through watergarden and aquarium trades 3. Statistical risk assessment for invasive aquatic plants in the Midwest
Invasion Process Species Elsewhere In Pathway e. g. imported for trade Introduced Reproducing Established Ecological &/or Economic impacts Invasive
Invasive Aquatic Plants In Indiana Eurasian watermilfoil (Myriophyllum spicatum) is established in 175 lakes and reservoirs, and many waterways Purple loosestrife (Lythrum salicaria) is established across IN Curly-leafed pondweed (Potamogeton crispus) ~$803, 000 spent each year just on herbicide control More spent on biocontrol Value of lost opportunities (boating, fishing etc. ) not estimated
Sources • Watergardening (e. g. purple loosestrife) • Aquariums (e. g. Eurasian watermilfoil, curly-leafed pondweed) • Landscaping, erosion control (e. g. reed canarygrass Phalaris arundinacea)
IN Regulations • Federal noxious weed list (19 species) + Lythrum – – – – – Azolla pinnata (mosquito fern) Caulerpa taxifolia (Mediterranean clone) Eichornia azurea (anchored waterhyacinth) Hydrilla verticillata Hygrophila polysperma (Miramar weed) Ipomoea aquatica (water spinach) Lagarosiphon major (Moss) Limnophila sessiflora (ambulia) Melaleuca quenquinervia Monachoria hastata Monochoria vaginalis Ottelia alismoides Sagittaria sagittifolia (arrowhead) Salvinia auriculata (giant salvinia) Salvinia biloba (giant salvinia) Salvinia herzogii (giant salvinia) Salvinia molesta (giant salvinia) Solanum tampicense (wetland nightshade) Sparganium erectum (exotic bur-reed)
Reducing The Impacts Invasion Steps Species Elsewhere × Introduced Established Invasive Options Effective? Prevention – exclude species of concern Yes Insure no propagules can escape cultivation Unlikely Rapid response eliminate populations while small Unlikely – requires surveys and funds on hand Mitigate damage, control spread, eradicate if possible Eradication usually impossible, control is expensive
Reducing The Impacts Invasion Steps Species Elsewhere Introduced × Established Invasive Options Effective? Prevention – exclude species of concern Yes Insure no propagules can escape cultivation Unlikely Rapid response eliminate populations while small Unlikely – requires surveys and funds on hand Mitigate damage, control spread, eradicate if possible Eradication usually impossible, control is expensive
Reducing The Impacts Invasion Steps Species Elsewhere Introduced Established × Invasive Options Effective? Prevention – exclude species of concern Yes Insure no propagules can escape cultivation Unlikely Rapid response eliminate populations while small Unlikely – requires surveys and funds on hand Mitigate damage, control spread, eradicate if possible Eradication usually impossible, control is expensive
Reducing The Impacts Invasion Steps Species Elsewhere Introduced Established Invasive Options Effective? Prevention – exclude species of concern Yes Insure no propagules can escape cultivation Unlikely Rapid response eliminate populations while small Unlikely – requires surveys and funds on hand Mitigate damage, control spread, eradicate if possible Eradication usually impossible, control is expensive
Summary: Part 1 • Invasive aquatic plants have significant ecological and economic impacts in Indiana • Most are intentionally introduced • Current regulations are inadequate • Preventing introduction is the best way to prevent future impacts
2. Species Available • What species are available? • Buy and identify organisms • What risks are posed? • Spread of known invaders • Introduction of new invaders
Organisms Purchased Trade Taxa Aquatic plants Fish Mollusks Crayfish Amphibians Worms Insects Water Pet garden X X X X Bait Live food Bio. supplies X X X X
Risks Posed - Plants • Availability of known invasives – 45% of US restricted plants available over web – Eurasian watermilfoil, curly-leafed pondweed, water chestnut and many more invasive, or potentially invasive, species • Misidentifications – 40% of Linnean names incorrect – Ambiguous common names
Contaminants - 5 snail species - 1 crustacean species - 2 insect species - duckweed (Lemna sp. )
Summary: Species Available • Watergarden and aquarium trades are spreading potential and known invaders • Plants are often incorrectly identified by vendors • Plant trade is a vector for the transfer of many contaminant species
Overall Conclusions • Invasive aquatic plant species are a significant economic and ecological problem in Indiana • Preventing introduction is the best way to stop further damages • Many actually or potentially invasive species are being spread through trades • Risk assessment is possible and accurate
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