Invasive species “On a global basis… the two great destroyers of biodiversity are, first habitat destruction and second, invasion by exotic species.” E.O. Wilson

Outline What are invasive species? Effects of invasive species. Invasive methods. Some common invasive species. Operation Cat Drop.

1. What are invasive species? Some definitions: Native: not introduced into that area by humans (delineates a native vs. non-native species). Introduced: species of plants, animals or other organisms introduced outside their natural past or present distribution, aka. exotic, alien, nonnative.

Invasive species are… Invasive: a species that becomes abundant and influential in a community of native species. Pest: any species that is not wanted by humans (exclusively a human construct).

Invasive species in North America More have been introduced into North America than any other continent: approx. 6,600 species (terrestrial, freshwater, marine). Very conservative estimate - doesn't account for many insects, freshwater organisms or plant pathogens.

Invasive species in North America This trend is continuing - between 1980 and 1993 more than 205 new species were discovered in the USA (probably an underestimate). After WWII ended, the world began to become much more of a global marketplace and international trade increased.

Invasive species in North America International trade is one of the main reasons why we have serious global problems with introduced species.

Invasive species in North America In the USA, introduced species have caused, or contributed to, the decline of 49% of all threatened or endangered species. Of those species, declines were due to: 15.8% - introduced predators or herbivores. 7.1% - competition. 0.8 % - diseases.

Invasive species in Anzac Australia and New Zealand have a worse problem than NA (even though they have a smaller total number of species introduced). Australia: has about 1,700 exotic plants (approx 21-43% of total flora). New Zealand: has about 1,570 exotic plants (about 47% of total flora) .

How do introductions occur? Deliberate introductions – species specifically released into new areas. Accidental introductions – species which were not intended to be released into new areas. Native invasives – changing the ecosystem to allow native species an “advantage” over other species.

Deliberate introductions marketable products in preexisting market ignorance of how to use native species comfort and familiarity with using introduced species cultural utility & comfort religious reasons & utility biological control ecological remediation ornamentals agricultural uses domestics sport

Accidental introductions travel (primary mode). trade (primary mode). parasites. augmenting natural dispersal abilities. removal of natural barriers. escapes of domestics. unprocessed natural products. ballast water.

Ballast water Ships crossing oceans use water to maintain stability at sea. Many aquatic organisms in ballast water.

Native invasives This occurs primarily through human action, such as: the removal of some restraining forces (e.g., predators). augmenting resources – food. augmenting resources – habitat (fragmentation and increased edges).

2. Effects of invasive species Impacts resulting from the presence of invasive species can be seen on several levels: Species. Communities & populations. Ecosystems.

Impacts on other species - 1 Invasive species may negatively impact native species directly by: eating them (predation, herbivory). competing with them. mating with them (thereby decreasing genetic diversity). introducing pathogens and parasites. disrupting available nutrient and tropic pathways. smothering native vegetation.

Impacts on other species - 2  Invasive species can alter ecosystems by: changing species composition. decreasing rare species. degrading the normal system functions.

Community & population level impacts Changes in vegetation structure. Alteration of community composition. Resource competition. Negative impacts on native wildlife. Population reductions, eliminations. Reduced recruitment of native species (succession). Hybridization with native species.

Ecosystem level impacts Disturbance regimes, i.e., timing and frequency of fires. Hydrology. Geomorphological processes (erosion, sedimentation). Soil chemistry (nutrients).

Impacts on natural areas In natural areas, nonnative plants can: reduce habitat for native and endangered species. degrade riparian areas. create fire hazards. interfere with recreational activities.

Impacts on aquatic systems Aquatic invasive species can: clog lakes and waterways. adversely affect fisheries. affect public water supplies, irrigation, and water treatment systems. inhibit recreational activities. affect shipping.

Zebra Mussel Introduced into Great Lakes via ballast water.

Zebra Mussel Distribution 1988 1999

Cost of invasive species Current estimated environmental, economic, and health-related costs of invasive species in the USA: $138 billion per year. This is more than all other natural disasters combined. Source: National Institute of Invasive Species Science US Geological Survey.

3. Invasive methods There are many ways in which invasive species move into new environments. Especially in the ways invasive species “get around”.

Aquatic Invasive Species Pathways - 1 Attached to external surface of vessels, such as: ships. oil rigs. floating garbage. Shipping, mainly in ballast water

Aquatic Invasive Species Pathways - 2 live food industry. bait. recreational boating. aquarium and horticulture trade. unauthorized fish transfer (i.e., illegal stocking).

Invasive plant species pathways - 1 gardening plants. nursery stock. restoration/remediation. ornamentals/seedlings. packing materials. grains/birdseed. wood products.

Invasive plant species pathways - 2 spread through wind, water, livestock. hitchhikers on transport systems. aquarium trade. soil/sod/gravel. escapes from research, botanical gardens. travel & tourism (incl. baggage). internet & mail order.

Invasive wildlife species pathways - 1 natural spread (wind, water vectors, carrier animals). importing animals for research purposes (including bacteria, viruses). transportation (air, sea, rail, road). pet trade/ zoo trade/ game farm trade. illegal importation.

Invasive wildlife species pathways - 2 In-directly related to cities: livestock (agriculture). fur farming. species introduced for hunting, fur harvest or subsistence use. travel/tourism.

4. Some common invasive species There are hundreds of invasive species, many of which find a perfect niche in cities.

Kudzu vine (Pueraria montana) Originally imported from Japan (1876) to landscape a garden in the Japanese Pavilion of the Philadelphia Centennial Exposition. Early 1900's - was discovered to be excellent forage for cows, pigs, and goats in the acidic soils of the US South; good during drought seasons.

Kudzu vine

My personal favourite… The Norway Rat (Rattus norvegicus)

Rats can… Swim up to half a mile; tread water for 3 days. Survive for 14 days without food (will resort to cannibalism if no food is available). Eat anything – is a true omnivore. Test foods for poison. Hunt animals larger than themselves. Migrate when rat population is too dense.

Rats can also… Produce 6-8 litters per year; one breeding pair can produce a colony of 2000 rats in one year. Climb vertical brick walls. Swim through water pipes. Survive very poor environmental conditions.

Norway Rat CV Considered to be the greatest mammal pest of all time. Harbors pathogens: bubonic plague, typhus, spotted fever, salmonella, etc., etc., etc…. Are usually a contributing factor in the spread of pandemics during war. Rat-borne diseases have caused more human deaths than all the wars in the history combined.

Norway Rat CV (there’s more) Cause considerable damage to agricultural crops. Deplete and pollute human food stores. Damage buildings through destructive chewing of wiring, pipes, and walls. Restrict plant growth by eating large amounts of seeds. Have caused the extirpation of many species. Decimated native bird and mammal species on many islands.

Some Edmonton invasives Edmonton may not have rats but it does have many other invasive species Dandelion Kentucky Bluegrass

Some Edmonton invasives Cabbage White Warthog

Some Edmonton invasives Pineapple Weed Seven-spotted Ladybug Foxtail Barley

Some Edmonton invasives Scentless Chamomile Russian Thistle

Some Edmonton invasives House Sparrow European Starling

5. Operation Cat Drop Let’s pause to consider what is arguably the most comical attempt at ecosystem modification through species introductions in history. This is proof that: “Truth is indeed stranger than fiction” (No further slides. Can’t let the kitties out of the bag quite yet…)