Aquatic Invasives to Watch for in the Tualatin River Watershed

Transcription

1 Aquatic Invasives to Watch for in the Tualatin River Watershed Table of Contents Report Invasive Species! In order to confirm species ID, we 1-Purple loosestrife recommend that people take photos of 2-Parrot feather the invasive plant or animal and pin their 3-Waterprimrose location to their online Oregon Invasives 4-Yellow floating heart Hotline Report at OregonInvasivesHotline. 5-Brazilian elodea org or report invasive species to 6-Eastern red-eared slider turtles inaturalist.org. 7-New Zealand mudsnails 8-Eurasian watermilfoil Stop the Spread of Invasive Species! 9-Hydrilla 10-Zebra and Quagga mussels Watch for invasive species, but don t spread them. If you get in water, clean and dry your boat, footwear and gear before 11-Flowering rush going to a new place. Learn more at playcleango.org. 12-European water chestnut Partners in this effort References -ODA Noxious Weed Profiles: programs/weeds/oregonnoxiousweeds/pages/aboutoregonweeds. aspx - On the Lookout for Aquatic Invaders: Identification Guide for the West by: Sea Grant Oregon

2 Purple loosestrife Lythrium salicaria Limited distribution in Washington County, but has potential to spread. Reddish-purple flowering spikes, square stems and opposite leaves that are hairy and lance-shaped. Grows up to 10 feet tall and has a broad appearance on the landscape due to the nearly 50 stems per plant. Prefers wet feet, but can survive in drier areas like agricultural pastures and fields near ephemeral ditches. Photo: Tyler Pedersen Mature plants can produce up to 2.7 million seeds annually which remain viable for at least three years. Has a welldeveloped taproot and can re-sprout from the stump when cut back. Degrades habitat quality for fish and waterfowl and out-competes native vegetation for space, light and pollinators. Blooms from July to August. 1 Parrot feather Myriophyllum aquaticum Primarily found in Multnomah, Clackamas and Marion Counties with a limited distribution in Washington County. Present in Fanno Creek and Cedar Mill/North Johnson Creek drainages. Native to South America. A popular aquatic ornamental plant used in aquariums and water gardens. Emergent aquatic plant that colonizes slow-moving lakes, ponds, streams and canals by rooting in the substrate with stems floating above the water. Stems can reach 15 feet long and are light green to reddish in color. Three to six whorls per node. Flowers from April to July. Photo: Glen Miller at ODA Infestations can block sunlight and oxygen exchange, reduce native plant diversity and fish production, and increase mosquito populations. Spreads vegetatively through fragmentation. 2

3 Waterprimrose Ludwigia hexapetala, peploides Heavy infestations present in Clackamas and Marion Counties, especially along the Willamette River. Can spread through the nursery trade as an aquatic garden plant. Perennial aquatic plant that occurs in marshes, swamps, ponds and lake margins. Stems and leaf veins are often reddish. Leaves are alternate, oblong (one to four centimeters), and clustered, tapering at the base into a stalk. Leaf margins are smooth. Flowers are yellow with five to six petals. Photo: Glen Miller ODA Creates dense floating mats that crowd out native species and degrade habitat quality for fish and other aquatic wildlife. Flowering occurs from mid to late summer. Spreads by seeds and vegetatively through fragmentation. 3 Yellow floating heart Nymphoides peltate Limited in Washington County. Occurs in Fanno Creek drainage. Emergent aquatic perennial with creeping rhizomes, floating heart-shaped leaves and five petaled yellow flowers. The three to five-inch diameter leaves are much smaller than the native yellow pond lily which has 12 to 14-inch leaves. Cultivated as a pond ornamental. Grows in dense stands that can decrease native plant and animal diversity, impede flows in irrigation canals, limit recreation and increase mosquito populations. Flowering occurs from May to October. Spreads primarily by seed and plant fragments. Photo: David Cappaert 4

4 Photo: Robert Videki, Doronicum Kft., Bugwood.org Brazilian elodea Egeria densa Limited in Washington County, although elodea can be found in every county in western Oregon because of aquarium dumping. Perennial submerged aquatic plant growing rooted to lake bottoms and reaching the surface in seven to eight-footdeep water. Stems grow up to 18 feet long. Dark leaves are joined in whorls of four to eight at each node and flowers are white and three petaled. Reproduction is primarily by plant fragments. Aggressively invades and alters aquatic environments while also impeding flows in waterways and interfering with recreational opportunities. 5 Photo: Royal Tyler, Pro Pest and Lawn Store, Bugwood.org Eastern red-eared slider turtles Trachemys scripta elegans Known to occur in Oregon, primarily due to release of aquarium pets into lakes and ponds. Prefers freshwater lakes and wetlands with abundant basking spaces. Identifiable due to telltale red or orange markings behind their eyes. Green shells are 6 to 16-inches long. Underbellies are yellow and there are yellow stripes along the neck and legs. Females are larger than males but males have longer claws on their front feet for mating purposes. Males and females reach sexual maturity at five to six years old with an average lifespan between 20 to 30 years. This large non-native turtle can out-compete two native turtle species (western pond turtle and western painted turtle) for food, basking and nesting spots. May also introduce new diseases into the local native turtle populations. 6

5 New Zealand mudsnails Potamopyrgus antipodarum Present in Central Oregon, the Oregon Coast, and throughout the Western United States. Small, aquatic snail with a brown, whorled shell (five to seven whorls). Found in lakes, rivers, streams and estuaries. Often introduced through ship ballast water. Can spread by hitchhiking on the wading gear, boats, and trailers of boaters and watershed workers. Their extremely small size, adaptability to extreme conditions and rapid reproduction enables snail populations to grow quickly (up to 100,000 per square meter!). They out-compete and displace native macro-invertebrates and can negatively impact fish species by disrupting nutrient cycling and the food chain. Photo: Mohammed El Damir, Bugwood.org 7 Photo: Vanessa Howard, PSU-CLR Eurasian watermilfoil Myriophyllum spicatum Limited distribution in Washington County on Fanno Creek drainage. Common throughout western Oregon due to spread by aquarium dumping, waterfowl, and plant fragments on boats and flood events. Perennial submergent aquatic plant that is rooted to the bottom and extends to the surface in shallow lakes and ponds. Stems can reach 12 feet long and are emersed only while flowering from June to September. Bract-like leaves develop just below each whorl of flowers. Primarily reproduces through stem fragmentation. Similar in appearance to parrot feather, although distinguished by purplish to red-branching stems with feather-like leaves in whorls of four at each node. Creates significant economic and ecological impacts to rivers, lakes, ponds and irrigation ditches, reducing water quality and quantity, impeding recreation and boat access, and degrading fish habitat. 8

6 Photo: Leslie J. Mehrhoff, University of Connecticut, Bugwood. Hydrilla Hydrilla verticillate Not yet known to occur in Oregon, but does occur in Washington and California. Perennial aquatic plant that is easily mistaken as an elodea species. Grows rapidly in the spring and remains rooted to the bottom with long stems reaching the water s surface. Leaves are 1/16 to 1/8 inch-wide and ¼ to ¾ inch long. It can develop roots from stem nodes and spread by tuber fragments. The nut-like turions (tubers) and whorls of five are a key feature that distinguish it from Brazilian elodea. Dense stands can decrease habitat quality and quantity for fish by raising ph, decreasing oxygen, and increasing temperature. Infestations can create stagnant water that breeds mosquitoes and interferes with recreational activities. 9 Pictured here Zebra Mussel Photo: Amy Benson, USGS, Bugwood.org Zebra Dreissena polymorpha & Quagga mussels Dreissena bugensis Not currently found in Oregon but rapidly spreading throughout the Great Lakes region and across much of the Mississippi River watershed in the ballast water of commercial cargo ships. Quagga mussels were discovered as far west as Lake Mead in Nevada and Lake Havasu and Mohave along the California-Arizona border. Small (up to 20 cm), striped, triangular-shaped freshwater bivalves found in lakes, rivers, canals, and ponds. They have huge impacts on ecosystems they invade and form dense colonies that can exceed 10,000 individuals per square meter. The primary vector is overland transport on trailered boats. Populations filter large amounts of water while feeding, causing bottom-up food-web effects that alter plankton blooms, biodiversity, and fish populations. They cause hundreds of millions of dollars worth of economic damage annually by clogging water-intake pipes. 10

7 Flowering Rush Botomus umbellatus Currently three known sites in Oregon near Boardman in the Columbia River. Perennial water-loving plant that is not a true rush species. It is easy to identify when flowering, difficult when not. Grows up to five feet tall as an emergent in deep water or in the lower marsh. Showy-white or pink flowers emerge in the late summer to early fall. Reproduces by rhizomes, bulblets, and seeds. Spreads primarily through moving water. Can outcompete native cattails and bulrushes, clog irrigation canals, and impede boat access. Photo: Leslie Mehrhoff, Bugwood.org 11 Photo: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org European water chestnut Trapa natans No sites have been identified in Oregon at this time, but please keep an eye out in Washington County. Annual aquatic plant forming dense mats at the surface of lakes, ponds and slow-moving waters. Emerging leaves occur in clusters up to 20 inches across and are diamondshaped with toothed edges. Submersed leaves are long, narrow and often replaced with green feather-like structures. Flowers are small, solitary, and white to light purple with sharp-spined fruits. An aggressive competitor in shallow waterbodies, forming dense mats that limit recreational access and reduce oxygen levels, thereby increasing the potential for fish kills. 12