OUTDATED Indicator V 2.0: Waterscapes: Fresh and Saltwater Connectivity
Summary
Fresh and Saltwater Connectivity This layer was one of the old South Atlantic LCC indicators in the waterscapes ecosystem. It was an index of dams preventing fish migration between rivers and the ocean. Fresh and saltwater connectivity was not performing well as an indicator and could not be used in Blueprint 2.0. This indicator was replaced in Blueprint 2.1 with a new migratory fish connectivity indicator. Reason for Selection Barriers to connectivity between rivers/streams and the ocean can strongly impact diadromous fish and alter natural movement of sediments, are easy to monitor and model, and are widely used and understood by diverse partners. Input Data Southeast Aquatic Connectivity Assessment Project: This project, a [...]
Summary
Fresh and Saltwater Connectivity
This layer was one of the old South Atlantic LCC indicators in the waterscapes ecosystem. It was an index of dams preventing fish migration between rivers and the ocean. Fresh and saltwater connectivity was not performing well as an indicator and could not be used in Blueprint 2.0. This indicator was replaced in Blueprint 2.1 with a new migratory fish connectivity indicator.
Reason for Selection
Barriers to connectivity between rivers/streams and the ocean can strongly impact diadromous fish and alter natural movement of sediments, are easy to monitor and model, and are widely used and understood by diverse partners.
Input Data Southeast Aquatic Connectivity Assessment Project: This project, a collaboration between The Nature Conservancy, the Southeast Aquatic Resources Partnership, and the South Atlantic LCC, identifies opportunities to improve aquatic connectivity by prioritizing dams based on their potential ecological benefit if removed or bypassed.
Mapping Steps
Indicators intended for use in Blueprint 2.0 were initially computed, or in the case of existing data, were resampled to 1 ha spatial resolution using the nearest neighbor method. For computational reasons, we then used the Spatial Analyst aggregate function to rescale the resolution to 200 m. The aggregate function avoided loss of detail by taking the maximum value of each cell in the conversion (e.g., species presence).
The Southeast Aquatic Connectivity Assessment Project summarized number of dams between each HUC12 subwatershed and the ocean to create this indicator. We then grouped this number of dams into 5 categories (0, 1, 2, 3, >3) and assigned indicator values to each category (4, 3, 2, 1, 0), with 4 being areas of highest quality for this indicator (0 downstream dams) and 0 being areas of lowest quality for this indicator (>3 downstream dams).
Defining the Spatial Extent of Ecosystems
Landscapes and waterscapes indicators were defined as features that applied across all terrestrial and aquatic ecosystems and no refined extent was needed.
Known issues
In some situations, this index of connectivity can improve even as you move upstream. This is because the calculation includes barriers off the mainstem of the river that are not necessarily “downstream” of other watersheds.
Indicator Overview
The South Atlantic ecosystem indicators serve as the South Atlantic LCC's metrics of success and drive the identification of priority areas for shared action in the Conservation Blueprint. To learn more about the indicators and how they are being used, please visit the indicator page. Check out the Blueprint page for more information on the development of the Blueprint, a living spatial plan to conserve our natural and cultural resources.
Literature Cited
Martin, E. H, Hoenke, K., Granstaff, E., Barnett, A., Kauffman, J., Robinson, S. and Apse, C.D. 2014. SEACAP: Southeast Aquatic Connectivity Assessment Project: Assessing the ecological impact of dams on Southeastern rivers. The Nature Conservancy, Eastern Division Conservation Science , Southeast Aquatic Resources Partnership. <maps.tnc.org/seacap>