Definition of Exotic Nuisance Alien Invasive Species and Native Indigenous Species

Discussions of  Invasives Aquatic Plants include many words we all recognize, but the context is unfamiliar and confusing when applied to plants.  In addition to the common usage, biologists use these terms to describe the ecological status of plant or animal populations and how they fit into a particular geographical region. Some terms are used interchangeably, such as nuisance and invasive, both with a negative connotation. Four categories (Binggeli, 1994) serve to cover the concepts used to describe the status and the distribution of a particular species.

1. Native, Indigenous: species naturally occurring or originating in a geographical region since prehistorical time;
2. Introduced, Alien, Exotic: deliberate or accidental release of a species into an area in which it has not occurred in historical times;
3. Invasive: the establishment of self-regenerating and spreading populations of a naturalized species in a free-living state in the wild, takes possession and may affect injuriously;
4. Nuisance, Noxious, Weed: any plant, either native or introduced, with a harmful or destructive influence on existing natural communities, interfering with the objectives or requirements of people.

These categories apply to biological communities, which are always evolving or changing due to fluctuating environmental conditions. Some species may be considered invasive if they occur in Maine but have been transported between watersheds and their introduction has caused detrimental effects to existing populations (e.g. introduction of white perch to brook trout waters has severely curtailed the beneficial values of brook trout in the affected waters). Some species in Maine fit into one or several of these categories, for example:

• Variable milfoil, a native plant this is invasive and a nuisance when spread to new waterbodies

• Bladderwort, a common native aquatic plant that is occasionally considered invasive

• Purple Loosestrife is a rapidly spreading exotic invasive in wetland habitat

• Brook Trout, a desirable native that is not a nuisance

• Brown Trout, an introduced species that is not invasive or considered a nuisance

• Gold Fish or Carp are exotics that are also considered noxious invasives

Binggeli, P. (1994) Misuse of terminology and anthropomorphic concepts in the description of introduced species. Bull. Brit. ecol. Soc. 25, 10-13.
http://members.tripod.co.uk/WoodyPlantEcology/invasive/terminology.htm