Ecosystem Viltality Biodiversity (BIO) Species of Concern (SoC)

March 28, 2019 at 1:36 AM

Changes in presence (i.e. species number) and population size of species of concern is first of two biodiversity sub-indicators. Species of concern should consist of native at-risk freshwater species (including but not limited to aquatic invertebrates, amphibians, fish and water birds) listed on the IUCN Red List as critically endangered (CR), endangered (EN), or vulnerable (VU) (IUCN 2012) and nationally and/or provincially listed threatened and endangered freshwater species occurring in the basin. Species of concern should also include carefully selected freshwater species whose status and population trends are linked to the health of the freshwater ecosystem, such that a change in freshwater ecosystem health would result in a change in the status or population trends of the species over time. These species might include umbrella, keystone, flagship or indicator species that might not be under threat but would be sensitive to changes in the freshwater system (Caro 2010). Local ecologists will be the best source for information on the identities and status and trends of such species. Monitoring data on population sizes or other measures of abundance, such as biomass or density, should be collected periodically for such additional species to be considered species of concern. Since this indicator evaluates changes in species of concern, species should be carefully selected at the outset – and there should be enough of them — so that a change in the number of species of concern adequately reflects genuine changes as the result of threats or beneficial management actions in the basin.

Calculation in FHI toolbox:

The index for species of concern is calculated in four parts: (1) calculation of the proportion of threatened and endangered freshwater species out of the total freshwater species assessed in the basin, (2) calculation of the change in the number (i.e., richness) of species of concern, and (3) the average population trend across all species of concern for which there is data. These three parameters are then (4) combined to give an overall index for the status and change in species of concern.

The first step in the calculation estimates the proportion of threatened and endangered freshwater species, of the total freshwater species assessed in the basin. For IUCN Red List species, total assessed species are those have undergone IUCN Red List assessments. Data Deficient (DD) species are excluded and the inclusion of species based on presence and origin are as per the two tables below:

Table 1

Presence Description Include in FHI assessment
Extant The species is known or thought very likely to occur presently in the area, usually encompassing current or recent localities where suitable habitat at appropriate altitudes remains. Yes
Probably Extant The species’ presence is considered probable, either based on extrapolations of known records, or realistic inferences (e.g., based on distribution of suitable habitat at appropriate altitudes and proximity to areas where it is known or thought very likely to remain Extant). ‘Probably Extant’ ranges often extend beyond areas where the species is Extant or may fall between them. Yes
Possibly Extant The species may possibly occur, based on the distribution of suitable habitat at appropriate altitudes, but where there are no known records. ‘Possibly Extant’ ranges often extend beyond areas where the species is Extant (q.v.) or Probably Extant (q.v.) or may fall between them. No
Possibly Extinct The species was formerly known or thought very likely to occur in the area, but it is most likely now extirpated from the area because habitat loss/other threats are thought likely to have extirpated the species and/or owing to a lack of records in the last 30 years. No for the first assessment. If no for first assessment no for continuing assessments. If species recorded Extant, Probably Extant or Possibly Extant for first or subsequent assessments, include for second step in the species of concern calculation.
Extinct (post 1500) The species was formerly known or thought very likely to occur in the area, but there have been no records in the last 30 years and it is almost certain that the species no longer occurs, and/or habitat loss/other threats have almost certainly extirpated the species. No for the first assessment. If no for first assessment no for continuing assessments. If species recorded Extant, Probably Extant or Possibly Extant for first or subsequent assessments, include for second step in the species of concern calculation.
Presence Uncertain The species was formerly known or thought very likely to occur in the area but it is no longer known whether it still occurs (usually because there have been no recent surveys). Yes

Table 2

Origin Definition Include in FHI assessment
Native The species is/was native to the area Yes
Reintroduced The species is/was reintroduced through either direct or indirect human activity. Yes
Introduced The species is/was introduced outside of its historical distribution range through either direct or indirect human activity Yes
Vagrant The species is/was recorded once or sporadically, but it is known not to be native to the area. No
Origin Uncertain The species’ provenance in an area is not known (it may be native, reintroduced or introduced) Yes