Invasive Species destroy biodiversity and cause extinction—empirics prove
(National Science Foundation. December 29, 2010. “What Triggers Mass Extinctions? Study Shows How Invasive Species Stop New Life.” http://www.nsf.gov/news/news_summ.jsp?cntn_id=118292)
An influx of invasive species can stop the dominant natural process of new species formation and trigger mass extinction events, according to research results published today in the journal PLoS ONE. The study of the collapse of Earth's marine life 378 to 375 million years ago suggests that the planet's current ecosystems, which are struggling with biodiversity loss, could meet a similar fate.Although Earth has experienced five major mass extinction events, theenvironmental crash during the Late Devonian was unlike any other in the planet's history. The actual number of extinctions wasn't higher than the natural rate of species loss, but very few new species arose."We refer to the Late Devonian as a mass extinction, but it was actually a biodiversity crisis," said Alycia Stigall, a scientist at Ohio University and author of the PLoS ONE paper. "This research significantly contributes to our understanding of species invasions from a deep-time perspective," said Lisa Boush, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research. "The knowledge is critical to determining the cause and extent of mass extinctions through time, especially the five biggest biodiversity crises in the history of life on Earth. It provides an important perspective on our current biodiversity crises." The research suggests that the typical method by which new species originate--vicariance--was absent during this ancient phase of Earth's history, and could be to blame for the mass extinction. Vicariance occurs when a population becomes geographically divided by a natural, long-term event, such as the formation of a mountain range or a new river channel, and evolves into different species. New species also can originate through dispersal, which occurs when a subset of a population moves to a new location. In a departure from previous studies, Stigall used phylogenetic analysis, which draws on an understanding of the tree of evolutionary relationships to examine how individual speciation events occurred. She focused on one bivalve, Leptodesma (Leiopteria), and two brachiopods, Floweria and Schizophoria (Schizophoria), as well as a predatory crustacean, Archaeostraca. These small, shelled marine animals were some of the most common inhabitants of the Late Devonian oceans, which had the most extensive reef system in Earth's history. The seas teemed with huge predatory fish such as Dunkleosteus, and smaller life forms such as trilobites and crinoids (sea lilies). The first forests and terrestrial ecosystems appeared during this time; amphibians began to walk on land. As sea levels rose and the continents closed in to form connected land masses, however, some species gained access to environments they hadn't inhabited before. The hardiest of these invasive species that could thrive on a variety of food sources and in new climates became dominant, wiping out more locally adapted species. The invasive species were so prolific at this time that it became difficult for many new species to arise."The main mode of speciation that occurs in the geological record is shut down during the Devonian," said Stigall. "It just stops in its tracks." Of the species Stigall studied, most lost substantial diversity during the Late Devonian, and one, Floweria, became extinct. The entire marine ecosystem suffered a major collapse. Reef-forming corals were decimated and reefs did not appear on Earth again for 100 million years. The giant fishes, trilobites, sponges and brachiopods also declined dramatically, while organisms on land had much higher survival rates. The study is relevant for the current biodiversity crisis, Stigall said, as human activity has introduced a high number of invasive species into new ecosystems.In addition, the modern extinction rate exceeds the rate of ancient extinction events, including the event that wiped out the dinosaurs 65 million years ago.
Results in trillions of dollars of losses
European Union 6
(“Developing an EU Framework for Invasive Alien Species.” http://ec.europa.eu/environment/nature/invasivealien/docs/ias_discussion_paper.pdf)
Invasive Alien Species (IAS) cause major economic problems related to their prevention, control and eradication (e.g. congestions in waterways, damages to forestry, to crops, to building property, damages in urban areas, etc.). Examples: - The costs of preventing, controlling and/or eradicating IAS and the environmental and economic damages are significant. The annual economic losses caused by introduced pests to crops, pastures, and forests in the United States, United Kingdom, Australia, South Africa, India, and Brazil amount to nearly US $230 billion. The annual environmental loss caused by introduced pests in the same countries were calculated at over $100 billion. The calculated cost per capita for the losses incurred due to biological invaders in the six nations investigated were approximately $240 per year. Assuming similar costs worldwide, damage from invasive species would be more than $1.4 trillion per year, representing nearly 5% of the world economy8 . - The introduced comb-jellyfish caused losses to the anchovy fisheries in the Black Sea estimated at $17 million annually9 . - IAS-related economic damage in Germany’s inland water systems from erosion of river banks and embankments is estimated at 32 million € per year for Fallopia species and 12 million € per year for Heracleum mantegazzianum and for the muskrat Ondatra zibethicus10. - The introduction of the salmon parasite Gyrodactylus salaries to more than 46 rivers and 37 aquaculture facilities in Norway has decreased the density of salmon by 86% in infected rivers. Losses of income and opportunities for recreational fishing due to Gyrodactylus salaries have been calculated to about 20 million €11. - Damage to the cultural and landscape and aesthetically valued areas caused by the introduction of insects and diseases which kill and maim trees in parks, urban areas and cultural valued tree plantings are substantial. The Chestnut leaf miner, Sudden oak death caused by Phytophtora species, Dutch elm disease has caused substantial economic costs in European cities, parks and cultural valuable landscapes for control measures and replacing trees which have been affected. From the economic perspective, biodiversity provides benefits for present and future generations by providing ecosystem services. However biodiversity provides not only ecosystem services to humans but also important values (emotional, cultural) loss of which means loss for future generations.
8 Pimentel, D., S. McNair, J. Janecka, J. Wightman, C. Simmonds, C. O’Connell, E. Wong, L. Russel, J. Zern, T. Aquino, T. Tsomondo 2001. Economic and environmental threats of alien plant, animal, and microbe invasions. Agriculture, Ecosystems and Environment 84 (2001) 1–20. 9 D. Knowler and E. Barbier (2000). The Economics of an Invading Species: A Theoretical Model and Case Study Application. The Economics of Invading Species. Edited by C. Perrings, M. Williamson and S. Dalmazzone. Edward Elgar, U.K. 10 Case study cited in SBSTTA 2005. The ecological and socio-economic impacts of invasive alien species on inland water ecosystems (UNEP/CBD/SBSTTA/10/1). 11 B.O. Johnsen (2006). NOBANIS Invasive Alien Species Fact Sheet – Gyrodactylus salaries. From Online Database of the North European and Baltic Network on IAS. NOBANIS www.nobanis.org