Arrive, Survive, and Thrive…It’s Not Necessarily a Good Thing

Ever heard of the International Day For Biological Diversity (IDB)? The United Nations declared May 22nd the official date this year, and Invasive Alien Species is the theme. Invasive Aliens Species are widely recognized as a major component of human-induced global environmental change. Globalization allows that the transportation of animals, plants and microorganism to provide a variety of goods and service, travel opportunities, as well as contributing to our personal well-being. It has also created entryways for invasive alien species to enter, establish and spread to new habitats and ecosystems. Climate change, disturbance and modification of landscape is also know as casing further spreading and impact of invasive alien species on a wide range of ecosystems.

These biological invasions by invasive alien species oftentimes result in economic losses and decreased biological diversity and ecosystem function. In the U.S. alone, the yearly damage and control cost of invasive species is estimated at over $138 billion….worldwide, the estimate is at 1.4 trillion — annually! Another shocking statistic? Invasive alien species have contributed to almost 40% of all animal extinctions for which the cause is known.

So how do they spread? Both intentionally and unintentionally. Natural ecosystems that have undergone human-induced disturbance are often more susceptible to alien invasions because there is less competition from native species. An example is the red fire ant. They are more successful in establishing themselves in disturbed areas such as roadsides and agricultural fields. They rarely colonized intact closed forests.

The movement of ships (and water) provides pathways for the movement of marine organisms from country to country and sea to sea. Hundreds of species can be found alive in samples taken from a single ship. People also have been known to introduce invasive alien species when they accidentally or knowingly release fish and plants into ponds, or flush them down the toilet…this ensures they find their way into local water systems.

Organisms may also hitchhike in or on timber, packaging, machinery equipment and vehicles. Items such as these are often shipped from place to place without cleaning. Airplanes also may allow species to move inside the cabin in passenger clothing, luggage, cargo, or aircraft parts. People may also transport species on soil-contaminated equipment, and bring home plants, plant parts or live animals, or food items such as fruits which may carry invasive insects or microbes.

Many important crops and trees (including plants for biofuel production) are grown in areas outside their natural distribution for effective food production. Sometimes when growing crops, biological control (a pest control strategy) using living natural enemies may be implemented. Oftentimes these exotic species which are used to control pest species, can become invasive pest species themselves.

To give you a larger perspective of invasive species impact on people and environments, one can look at history:
1. The Irish potato famine in the 1840’s was caused by a fungus introduced from North America.
2. The viruses causing smallpox and measles spread from Europe to the Western Hemisphere right after colonization. The low resistance of indigenous peoples to these parasites played a part in bringing down the Inca and Aztec empires.
3. The Nile perch: As the population grew and fishing techniques improved on Lake Victoria in Africa, by the 1950’s overfishing caused a drastic decline in fish stocks. To reverse this, the British introduced the Nile perch and Nile tilapia. With no natural predators and lots of prey, they flourished…and 200 species became extinct. The Nile perch (oilier than the other fish) required the locals to dry them over a fire before eating. More trees were used to do this, which resulted in deforestation. The deforestation caused increase erosion and runoff, which raised nutrient levels in the lake. This promoted infestation by water hyacinth.

Climate change also plays its part in the introduction of invasive alien species. Increasing ocean temperatures facilitates marine alien species invasions by increasing the magnitude of their growth. This facilitate a shift to dominance by aliens. Climate change is predicted to affect marine organism by:
1. Increasing ocean temperatures
2. Increasing Sea levels
3. Changing ocean circulation
4. Decreasing ocean salinity

So many factors directly alter conditions and contribute in some way as a threat to biodiversity. I know that the first colonists that landed at Plymouth rock were determined to arrive, survive (that first harsh winter), and thrive – but alien species moving into your own backyard which are able to arrive, survive and thrive; impact your own well-being, your community, and what’s left for future generations.

Don’t forget the International Day for Biological Diversity — this Friday May 22nd!