The Trouble with Invasive Species

Definitions Non-Native/introduced/alien/exotic species Species found outside their native range Got there with the help of humans Populations are growing without human assistance Invasive Species Introduced species that are causing problems ($$$ & loss of biodiversity)

What’s the problem? i.e. Zebra mussels Decrease biodiversity Out-compete and displace native species Change ecosystem Change water clarity Concentrate toxins (PCB’s) Zebra mussels are native to western Russia and were first discovered in the Great Lakes in 1988. They have since spread considerably (see distribution map on next slide). Species interactions: -Outcompete and displace natives: the tiny little zebra mussel attaches itself to everything, including native mussels. By completely coating these native mussles, the zebra mussel can kill the native species. The lower right picture features a native paper shell mussel that is being taken over by zebra mussels. Zebra mussels can also cover other things living in the water, like the crayfish pictures in the lower left. They attach to hard surfaces with byssal threads shown in the center photo. -Change ecosystem: zebra mussels eat phytoplankton that they filter from the water column. One zebra mussel can filter one quart of water each day. Now imagine how much water gets filtered by millions of zebra mussels living in a body of water! This results in much clearer water. All this filtering may seem like a good thing, but unfortunately it’s not. You see all the native plants and animals that live in the water are adapted to the conditions prior to zebra mussels. This means that a lot of the fish and friends can not survive in very clear water. Concentrate toxins: also as a result of their crazy filtering, zebra mussels concentrate toxins, like PCB’s which make people and wildlife very sick, in their bodies. Typically the toxins are present in the water in very low concentrations, but when the toxins get filtered by the zebra mussels they stay in the zebra mussels and because the zebra mussels filter so much water this results in much higher concentrations of the toxins. This becomes a problem because other animals that eat the zebra mussels and get a high dose of poison. At some point all this poison may even reach humans that eat the fish that ate the fish that ate the zebra mussel. For more on zebra mussels: http://www.dnr.state.wi.us/org/caer/ce/eek/critter/invert/zebramussel.htm

Zebra Mussels Economic cost Clog intake pipes Change communities Estimated cost = $5 billion over next 10 years Not only are zebra mussels a problem for native species, they also cause a lot of economic problems. They attach to everything, as you can see from the shopping cart, buoy, and intake valve pictures (intake valve picture not from .gov website). This can cause boats to malfunction and clogged intake valves can cost millions of dollars to unclog. Plus, there are commercial fisheries that depend on certain native fish species to harvest and when the zebra mussels clear up the water the commercial fish may disappear (see previous slide).

Why are some invasive species so successful? 1. Characteristics of “good” invaders Competitive Reproduce quickly Grow fast #2 (reproduce a lot and quickly) was one of the attributes of Troubles. Ask students to describe how Tribbles reproduced.

Why are some invasive species so successful? 2. “Enemy escape” hypothesis Most invasives are not considered a problem in their native range But they Escape natural predators and parasites in their new range nothing to keep population in check 3. Characteristics of an invaded community Disturbed area Spock described the enemy escape hypothesis in the Trouble with Tribbles. See if students can figure out what it is.

How do invasives arrive? A. Accidental transport Agricultural produce Ballast water There are many pathways by which invasive species arrive, all are due to some sort of human activity. Accidental transport: some people think that fire ants hitched a ride here on potted plants. Ballast water, which is water that ships take on in their home port for balance and then empty in the destination port, can contain millions of organisms native to the home port that are being introduced. Ballast water is a very serious problem, but fortunately people are looking for ways to avoid dumping all those exotic species in new harbors. Ballast water is probably how zebra mussels got to the U.S. For more info see: http://www.intertanko.com/tankerfacts/environmental/ballast/ballast.htm .

How do invasive get here? B. Intentional introductions European Starling European Starling - introduced Believe it or not, many invasives have been released on purpose! A crazy example, is of a guy who lived in New York City in the late 1800’s that released every bird species ever mentioned in Shakespeare into Central Park (that’ show the European Starling was introduced). There were even organizations, called acclimatization societies, whose sole purpose was to introduce plants and animals from other places. The European starling, introduced by the over-zealous Shakespeare fan, out-competes the native bluebird for nesting cavities. As a result of the starling, bluebird populations declined severely. Fortunately, people recognized the threat of starlings and starting erecting bluebird boxes with an entrance that was too small to allow starlings to enter and the population has rebounded. Eastern Bluebird - native

How do invasive get here? Intentional introductions Kudzu These things are not often done now, but there are still examples of organisms intentionally released. For example, kudzu, a vine native to Asia, was planted by the government forage crop and to prevent soil erosion, but now it blankets most of the southeast and is smothering native vines, trees, and shrubs. It is estimated that kudzu causes $500 million per year in control costs and damages! For more info on Kudzu see: http://www.jjanthony.com/kudzu/ http://www.personal.psu.edu/users/m/s/msk215/Kudzu%20Taxonomy.htm Not only did the government platn kudzu, it actually paid farmers to plant it too!

How do invasive get here? Landscaping Lantana Purple Loosestrife Many invasive plants got their start as garden ornamentals. One such invasive species that started this way was lantana. The problem with lantana is that it out-competes native lantana. However, I have not been able to find a way to tell native lantana from invasive lantana. Therefore, I won’t buy any lantana for my garden (even though butterflies love it) until I can figure this out - it’s better to be safe than sorry!

How do invasive get here? Escape/release Accidental escape People releasing unwanted pets Eradication/control of other species Feral cats kill native songbirds all the time. One rough estimate is that cats kill hundreds of millions of birds a year. The yellow-eared slider turtle, pictured in the middle, was introduced because people released them into the wild when they didn’t want to care for them anymore. They are now very common in Florida. You can tell the yellow-eared sliders from native sliders by the yellow behind their eyes.

Control Measures The best thing to do? Prevent the invasion!!! Physical removal/hunting Chemical control Biological control All Often extremely expensive The best thing to do? Prevent the invasion!!!

Control Measures Physical removal Air potato is a vine that grows very quickly and, like kudzu, can kill trees and shrubs by completely covering them. Gainesville hosts the annual great air potato roundup in which volunteers pull air potato wherever they find it. The potatoes that it produces are not edible. Air potato is native to Africa and was introduced to the U.S. during the slave trade.

Control of Fire Ants Chemical control To treat all areas with fire ants with pesticide would cost $6 - $12 billion per year! Biological control Decapitating flies Fire ant disease The cost to treat all of the areas invaded by fire ants with pesticide would cost $6 billion to $12 billion a year (USDA 2005)! Other solutions include biological control, in which natural enemies of fire ants from South America are introduced. The USDA has two biological control organisms for fire ants. The first are decapitating flies that lay their eggs in the heads of worker ants, which results in the ants’ head falling off. When the adult flies emerge from the decapitated heads they go on to infect other fire ants. The second biological control is a disease that reduces the ants’ reproduction.

Invasive Species in Florida Hydrilla Africanized / Killer bees Africanized honeybees, also known as killer bees, were intentionally introduced to Brazil from Africa in the 1950’s to increase honey production. They have since spread from Brazil to North America. One problem with Africanized honeybees is that they are much more aggressive than regular European honeybees and will aggressively attack anything that comes near their hive. They typically can only kill someone if they can not get away from them. Another problem with Africanized bees is that they hybridize with European bees, resulting in a decrease in the amount of honey produced, which leads to loss of $$$ for beekeepers. Killer bees are not widespread in Florida, but there have been a few spottings. Hydrilla was introduced when someone dumped their aquarium in a Florida waterway. Now hydrilla is found in almost every waterway in Florida. It poses a problem because it can completely clog the lake/river/stream/etc. within two years of arriving. For more info on hydrilla: http://www.dep.state.fl.us/lands/invaspec/2ndlevpgs/pdfs/hydrilla.pdf

Idaho Invasive Species Whitetop Cane toad Asian Longhorned beetle St Johnswort Thistle

Idaho Invasive Species Seeds Gets in dogs Paws and ears

Idaho Invasive Species Purple Loosestrife Goat head - Puncture vine