• Determine where to start protection and management for a range of intact aquatic systems
• Identify areas and networks of high ecological value
• Pinpoint important terrestrial areas (aquatic buffers) where protection and restoration actions can benefit the integrity of aquatic core areas
• Restore connectivity to otherwise intact areas

The aquatic core network can serve as a starting point for a regional conservation network that can be used in combination with other sources of information to direct action.  You might explore it in combination with:

• Other data layers to identify additional areas of high ecological value. Layers to consider include: 1) the terrestrial core-connector network, 2) The Nature Conservancy’s (TNC) Freshwater Resilience Networks, 3) the aquatic Index of Ecological Integrity, 4) habitat maps for Common Loon and important fish species (brook trout, Atlantic salmon, and other anadromous species), and 5) habitat condition for imperiled species.
• Aquatic connectivity restoration priorities to identify areas where restoring connectivity will add value to areas that are already intact.
• The secured lands layer to identify aquatic core areas and buffers that remain unsecured from development, and thus could represent priorities for protection.
• The probability of development layer and regional vulnerability layers to identify places in the aquatic core area network that are relatively vulnerable to future development, and thus could represent priorities for protection.
• Resource priorities identified at the state or local level, but that are not available across the entire region (e.g., from State Wildlife Action Plans, towns, and land trusts), to further rank areas for land protection.

With a free DataBasin account, you can upload your organization’s priorities into a private map for comparison with the terrestrial core-connector network, or you can download the network for analysis in your own GIS.

1. The most intact, resilient locations of each of 21 stream habitat classes and 12 lake/pond habitat classes in large watersheds (HUC6 level) across the Northeast and Mid-Atlantic. These classes were mapped by The Nature Conservancy working with the Northeast state fish and wildlife agencies and the North Atlantic LCC (Olivero and Anderson 2008). The integrity of these systems was assessed using the Index of Ecological Integrity developed by the University of Massachusetts Amherst (McGarigal et al. 2016).
2. Lotic (river and stream) core areas representing the highest probability of occurrence for Eastern brook trout (representative species for cold headwater streams) not captured by lotic ecosystem cores. Brook trout current probability of occurrence is based on a model developed by Ben Letcher and colleagues at the USGS Conte Anadromous Fish Lab.
3. Known stream reaches with existing occurrences for Atlantic and shortnose sturgeon and sea-run (salter) brook trout, along with top 5% of watersheds for alewife, American shad, and blueback herring, based on analyses by Trout Unlimited and The Nature Conservancy.
4. Priority rearing habitat for Atlantic salmon in the Gulf of Maine watershed, as mapped by the U.S. Fish and Wildlife Service and NOAA, where not otherwise already captured.
5. Lentic (lake and pond) cores representing the highest landscape capability for breeding common loon (representative species for intact northern lakes) not captured by lentic ecosystem cores. Common loon habitat capability for the region has been mapped by UMass Amherst (McGarigal et al. 2016).

Collectively, the river and stream cores encompass about 30% of the stream miles of the Northeast and Mid-Atlantic region. The lake and pond cores encompass about 30% of the lake and pond area of the region, not including the 14 lakes larger than 20,000 acres in the region.
Once the aquatic core areas were identified, aquatic buffers were defined to depict upslope and upstream areas most likely to have a strong influence on the integrity of the aquatic core areas through processes such as runoff.

• The results do not incorporate important social, economic, or feasibility factors.
• Users are cautioned against using the data on too small an area (for example, a small parcel of land), as the data may not be sufficiently accurate at that level of resolution.
• The classification and mapping of aquatic ecological systems is known to be imperfect, which consequently affects the mapped values for ecosystem integrity and species habitat. While the ecosystem mapping is anticipated to correctly reflect broad patterns of ecosystem occurrence, errors in classification and placement do occur, as with any regional GIS data. In addition, errors in mapping and alignment of hydrography, development, roads, traffic rates, and a number of other data layers can affect the model results.

• It is not possible to map all factors affecting ecological integrity and species habitat across the Northeast, and the omission of such factors can be anticipated to create some limitations in the results. Examples are listed below.
  • The aquatic core networks do not currently account for flow impairment as this information is only available at the medium resolution (1:100k) hydrography.
  • The aquatic core networks do not include information on non-indigenous aquatic species, or instream habitat quality because the available data are too coarse (HUC 8 watersheds) for the region.
  • Core areas do not account for instream habitat quality because there are no consistent data across region; partners can incorporate local or state data if available.
• The core area network approach by design does not explicitly identify the most important areas for rare aquatic species; however some additional areas are covered with the Habitat Condition for Imperiled Species dataset component and should be used as a complement to the aquatic cores networks.
• No one segment of a stream or river, such as depicted by a lotic core, can be conceived of as independent of the larger, continuous stream network of which it is a part. Core areas define particular areas of high integrity and importance to aquatic species, but ultimately conservation of the full network is critically important as well.

Inputs to aquatic core networks

   Northeast aquatic classifications for rivers and streams and lakes and ponds

   Index of Ecological Integrity

Additional documentation from UMass Designing Sustainable Landscapes project