Water lettuce: H. Smith, OFAH Giant hogweed: L.Assinck, MNRF Address pathways of introduction 08 Giant Hogweed Giant hogweed is a perennial ornamental garden plant originally from southwest Asia. Giant hogweed is a health concern for nature enthusiasts as it can cause severe skin burns if you get the sap on your skin and the skin is then exposed to sunlight. Symptoms occur within 48 hours and consist of painful blisters. Eye contact with the sap has also been reported to cause temporary blindness. Invasive Species to be on the Watch For Asian carp Asian carps were introduced to North America from Asia in the 1960’s and 1970’s. To prevent these unwanted invaders from coming into the province, Ontario has regulated four species of Asian carp (Silver carp, Bighead carp, Grass carp, Black carp) as prohibited invasive species under the Invasive Species Act, 2015. Asian carp can have extreme impacts on cottage country. Some species of Asian carp have the ability to eat the food supply that our native fish depend on and crowd them out of their habitat. The decline of native fish species could damage sport fishing in Ontario’s lakes. Silver carp are also a hazard for boaters. The vibration of boat propellers can make Silver carp jump up to three meters out of the water. Boaters and water-skiers in areas of the Mississippi and Illinois rivers have already been seriously injured by the jumping fish. Red Swamp Crayfish Red swamp crayfish (Procambarus clarkii) are a species of crayfish that are native to the Gulf Coast and Mississippi River drainage to Illinois. The Red swamp crayfish can quickly dominate lakes, rivers and wetlands. They feed voraciously on plants, snails, fish, and amphibians, aggressively competing with native crayfish and other species for food and habitat. Their presence can lead to declines in native crayfish. The Red swamp crayfish is not established in Ontario but poses a serious threat to biodiversity if it arrives in the province. Never release aquarium species into the environment. 09 Pathways are the routes by which invasive species move from one geographical location to another and how they are spread to new areas once they arrive. Natural pathways may include wind, water and animal dispersal. However these natural pathways are less to blame for species introductions and act more as a means of spreading an invasive species after it has already arrived. Human activity is the cause of most invasive species introductions. Invasive species can be transported unintentionally as “stowaways” in shipping containers, recreational boats and vehicles, firewood etc. They can also sometimes be introduced intentionally as products in trade (e.g. garden plants, aquariums etc.) Climate change is also a cause for concern with regards to the spread of invasive species into Ontario. A warmer climate may result in species that are adapted to warmer temperatures expanding their range northward as the environment becomes more suitable. An example of this kind of invasive species is Water lettuce. Water lettuce is an aquatic plant that is native to the southeastern United States. While not usually able to tolerate cold temperatures, several populations of water lettuce have been observed in Ontario, and they may be successfully reproducing. As winter temperatures increase so does the chance of survival of these aquatic plants. If Water lettuce continues to spread it could disrupt the plant and animal life in other waterways and interfere with recreation. Grass carp: J. Henry, MNRF Red swamp crayfish, iStock Did you know? Asian carp can consume up to 40% of their body weight each day; this leaves little food for native fishes to eat. They typically weigh 2-4kg (4-9lbs) but can weigh up to 40kg (88lbs) and reach more than a metre (3.3ft) in length. (OFAH Invading Species Awareness Program)