<P> Invasive species can change the functions of ecosystems . For example, invasive plants can alter the fire regimen (cheatgrass, Bromus tectorum), nutrient cycling (smooth cordgrass Spartina alterniflora), and hydrology (Tamarix) in native ecosystems . Invasive species that are closely related to rare native species have the potential to hybridize with the native species . Harmful effects of hybridization have led to a decline and even extinction of native species . For example, hybridization with introduced cordgrass, Spartina alterniflora, threatens the existence of California cordgrass (Spartina foliosa) in San Francisco Bay . Invasive species cause competition for native species and because of this 400 of the 958 endangered species under the Endangered Species Act are at risk </P> <P> Primary geomorphological effects of invasive plants are bioconstruction and bioprotection . For example, Kudzu Pueraria montana, a vine native to Asia was widely introduced in the southeastern USA in the early 20th century to control soil erosion . While primary effects of invasive animals are bioturbation, bioerosion, and bioconstruction . For example, invasion of Chinese mitten crab Eriocheir sinensis have resulted in higher bioturbation and bioerosion rates . </P> <P> Some invasions offer potential commercial benefits . For instance, silver carp and common carp can be harvested for human food and exported to markets already familiar with the product, or processed into pet foods, or mink feed . Water hyacinth can be turned into fuel by methane digesters, and other invasive plants can also be harvested and utilized as a source of bioenergy . </P> <P> Non-native species can have benefits . Asian oysters, for example, filter water pollutants better than native oysters . They also grow faster and withstand disease better than natives . Biologists are currently considering releasing this mollusk in the Chesapeake Bay to help restore oyster stocks and remove pollution . A recent study by the Johns Hopkins School of Public Health found the Asian oyster could significantly benefit the bay's deteriorating water quality . Additionally, some species have invaded an area so long ago that they have found their own beneficial niche in the environment, a term referred to as naturalisation . For example, L. leucozonium, shown by population genetic analysis to be an invasive species in North America, has become an important pollinator of caneberry as well as cucurbit, apple trees, and blueberry bushes . </P>

What is not an impact that an invasive non-native species has on an ecosystem