Introduced Species

Introduced Species - Definition European Rabbit in Australia An organism that is not indigenous to a given location but instead has been accidentally or deliberately introduced to a new location by human activity or by natural means.

Problems with Introduced Species Introduced species sometimes are damaging to the ecosystem they are introduced into.

Problems with Introduced Species Negatively affect agriculture and other human uses of natural resources or impact on the health of animals and humans. Compete with native species for food and habitat.

Intentional Introductions Perhaps the most common motivation for introducing a species into a new place is that of economic gain.

Example #1 Eurasian Carp Introduced to U.S. as a potential food source.

Problems associated with Carp Uproots plants in waterways(damaging) Compete with native fish and shellfish for food.

Example #2 European Starlings Interesting Fact: One example of introducing an exotic animal was carried out by a lover of the works of Shakespeare who wanted to introduce all of the birds mentioned in Shakespeare's plays into the United States. He deliberately released eighty starlings into Central Park in New York City in 1890, and another forty in 1891. There are now more European starlings in the U.S. than people.

Problems with European starlings Accumulated droppings may kill trees by their chemical concentration In smaller amounts, the droppings are beneficial as a fertilizer.

Example #3 Ornamental Plants The transport of ornamental plants for landscaping use has and continues to be a source of many introductions.

Some of these species have escaped horticultural control and become invasive. Examples include Norway spruce, water hyacinth, and purple loosestrife.

Invasive Species Invasive species are widespread non-indigenous species. They don’t naturally occur in the ecosystem. Therefore, they may out-compete native species Exploit resources – HUGE FOOD SOURCE No natural predators

Example #1 Purple Loosestrife (plant) Arrived on ships or in the ballast water on ships. The plants grow vigorously and spread very fast. A single plant may produce up to three million tiny seeds annually. Easily carried by wind and water, the seeds germinate in moist soils after overwintering.

Infestations result in: a dramatic disruption in water flow in rivers and canals a sharp decline in biological diversity as native food and cover plant species, notably cattails, are completely crowded out, and the life cycles of organisms from waterfowl to amphibians to algae are affected.

Example #2 Zebra Mussel It is believed that zebra mussels were introduced into the great lakes in the ballast water of ocean-going ships traversing the St. Lawrence Seaway. Another possible mode of introduction is on anchors and chains, although this has not been proven. Zebra mussels are very prolific animals. An adult female zebra mussel may produce between 30,000 and 1 million eggs per year.

Zebra mussels kill native mussels by out-competing and/or suffocating the native species May cause native mussels to go extinct Zebra mussels also damage harbors, boats, power plants, and water treatment plants; mostly by clogging pipes.

Example #3 Snakehead Fish First discovered in Crofton MD in 2002. Preys on native species. Competes in the same niche of native species.

As a family, snakeheads are native to parts of Asia and Africa As a family, snakeheads are native to parts of Asia and Africa. The Northern Snakehead is native to China, and possibly Korea and Russia. Introduced by being released from fish markets in Asia.

Introduced Species as Biological Controls Beneficial relationships A classical biological control is the introduction of natural enemies (predator/prey) to a new ecosystem where they did not originate or do not occur naturally. There are many examples of successful classical biological control programs.

Example #1 Ladybugs Ladybugs eat aphids (pests) on fruit plants and ornamental flowering plants, like roses.

Example #2 Vedalia Beetle (red/black) This beetle was introduced to control the cottony cushion scale insect, a pest that was devastating the California citrus industry. Within a few years the entire population of the cottony cushion scale was controlled.

REMEMBER THIS!!! Introduced species may become invasive species. May compete within the same niche as native species May compete for same food and habitat as native species. Introduced species may be used as biological controls to control pests. (Usually introduced by the government)