Ecosystem Viltality Biodiversity (BIO) Invasive Species (IS)

Changes in presence and population size of invasive and nuisance species is the second of the two biodiversity sub-indicators. Invasive and nuisance species are non-indigenous or alien species that “threaten the diversity or abundance of native species, the ecological stability of infested waters, or commercial, agricultural, aqua cultural or recreational activities dependent on fresh waters” (Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990). All known invasive and nuisance species that occur and pose a threat to freshwater health in the basin should be identified. The Global Species Data Base and any other available databases for the region can be used to identify such species. However, local expert knowledge should be used to verify the presence and identity of invasive and nuisance species in the basin. Monitoring data on population sizes or other measures of abundance, such as biomass, density or area or extent of cover, should be gathered for as many of these species as possible. A change in the indicator value should reflects either a greater intensity of threats posed by the increases in invasive or nuisance species or a lessening of such threats due to beneficial management actions that reduce their populations within the basin.

Calculation in FHI Toolbox:

The index for invasive and nuisance species is calculated in four parts: (1) an index denoting the number (i.e., richness) of invasive and nuisance species, (2) a calculation of the change in the number of invasive and nuisance species, and (3) the average population trend across all invasive and nuisance species for which there is data. These three parameters are then (4) combined to give an overall index for the status and change in invasive and nuisance species.