Invasive Species
Aquatic Environments
Cities, especially those that serve as major international hubs like Seattle, are particularly susceptible to invasive species due to the massive influx of people arriving every day from all over the world. In aquatic habitats, this often occurs with ballast discharged from massive ships, as foreign ships with thousands of tons of sea water from their native ports discharge their ballast in the Puget Sound (see diagram on right).
Terrestrial Environments
Invasive terrestrial plants are also a major concern. In fact, in King County alone there are over 100 identified noxious weeds and many are so widespread that control and eradication are virtually impossible [14]. The problem with many of these plants, both terrestrial and aquatic, is that they tend to create a mat of dense ground cover, effectively choking out native plants that once grew there.
Cities, especially those that serve as major international hubs like Seattle, are particularly susceptible to invasive species due to the massive influx of people arriving every day from all over the world. In aquatic habitats, this often occurs with ballast discharged from massive ships, as foreign ships with thousands of tons of sea water from their native ports discharge their ballast in the Puget Sound (see diagram on right).
Terrestrial Environments
Invasive terrestrial plants are also a major concern. In fact, in King County alone there are over 100 identified noxious weeds and many are so widespread that control and eradication are virtually impossible [14]. The problem with many of these plants, both terrestrial and aquatic, is that they tend to create a mat of dense ground cover, effectively choking out native plants that once grew there.
Fauna
Other times, invasive plants have detrimental effects on the natural fauna as well. One such example is the invasive butterfly bush, so named because it attracts butterflies. Unfortunately, while the prevalence of the bush increases, butterflies will not lay their eggs on it because it holds no nutritional value for the caterpillar, thus leaving them with less and less space to lay their eggs. In addition, the bush attracts insects so well that insects neglect and do not pollinate the native flora nearby [14].
Secondary Sources
13. "The Problem." GloBallast. GloBallast Partnerships -, n.d. Web. 25 Feb. 2014. <http://globallast.imo.org>.
14. "Invasive Species and Biodiversity in King County." Animals, Plants and Habitat. King County, n.d. Web. 25 Feb. 2014. <http://www.kingcounty.gov/environment/animalsAndPlants/biodiversity/threats/Invasives.aspx>.
Other times, invasive plants have detrimental effects on the natural fauna as well. One such example is the invasive butterfly bush, so named because it attracts butterflies. Unfortunately, while the prevalence of the bush increases, butterflies will not lay their eggs on it because it holds no nutritional value for the caterpillar, thus leaving them with less and less space to lay their eggs. In addition, the bush attracts insects so well that insects neglect and do not pollinate the native flora nearby [14].
Secondary Sources
13. "The Problem." GloBallast. GloBallast Partnerships -, n.d. Web. 25 Feb. 2014. <http://globallast.imo.org>.
14. "Invasive Species and Biodiversity in King County." Animals, Plants and Habitat. King County, n.d. Web. 25 Feb. 2014. <http://www.kingcounty.gov/environment/animalsAndPlants/biodiversity/threats/Invasives.aspx>.