Identifying Key Biodiversity Areas in Canada

Using the Connectivity Status Index (CSI) to assess ecological integrity in river catchments

Key Biodiversity Areas (KBAs) are sites with important characteristics for conserving biodiversity and wildlife habitats. The KBA Canada Coalition is gathering knowledge and adapting global KBA standards in order to identify and map critical terrestrial and freshwater sites for nature in Canada.

The Connectivity Status Index (CSI) can act as an indicator for ecological intactness of freshwater ecosystems. This novel metric was developed by Grill et al. (2019) in their study to map the global extent of ‘free-flowing rivers’. The CSI quantifies the degree to which an individual river reach (i.e. the short river segment between two tributaries) remains connected to its neighboring reaches within the larger river network. River connectivity is defined to extend in four dimensions: longitudinal (connectivity between up- and downstream river reaches), latitudinal (connectivity to floodplains and riparian areas), vertical (connectivity to groundwater and atmosphere), and temporal (connectivity based on seasonality of flows).

The CSI as described above can be used as a standardized index to analyze human pressures on river connectivity. The CS index is originally calculated at the river reach scale but can be aggregated to larger spatial extents that represent hydrographic units (catchments) to be selected as a KBA.

We produced statistics of (aggregated) CSI values over multiple spatial scales (using HydroBASINS) to assess ecological integrity and to inform the selection of Key Biodiversity Areas in Canada.

We developed a python model that allows for the automated aggregation of CSI values at the different scales of HydroBASINS (levels 1-12). We used this model to derive a set of ecological integrity metrics for each sub-catchment at every HydroBASINS level within Canada.