Geomorphology and Sustainable Subsistence Habitats

Climatic, tectonic, and human-related impacts are changing the distribution of shoreline habitats and associated species used as food resources. There is a need to summarize current and future shoreline geomorphic – biotic relationships and better understand potential impacts to native customary and traditional gathering patterns. By strategically integrating Native knowledge and observations, we create an inclusive vulnerability assessment strategy resulting in a win-win opportunity for resource users and research scientists alike. 

We merged the NOAA ShoreZone database with results from over sixty student intern discussions in six southeast Alaska Native communities. Changes in shore width and unit length were derived using near shore bathymetry depths and available isostatic rebound, tectonic movement, and rates of sea level rise. Physical attributes including slope, substrate, and exposure were associated with presence and abundance of specific species. Student interns, selected by Tribes and Tribal associations, conducted resource-based discussions with community members to summarize species use, characteristics of species habitat, transportation used to access collection areas, and potential threats to habitats. Geomorphic trends and community observations were summarized to assess potential threats within a spatial context.

Given current measured rates of uplift and sea level rise, 2.4 to 0 m of uplift along with 0.20 m of sea level rise is expected in the next 100 years. Coastlines of southeast Alaska will be subject to both drowning (primarily to the south) and emergence (primarily to the north). We predict decreases in estuary and sediment-dominated shoreline length and an increase in rocky habitats. These geomorphic changes, combined with resident's concerns, highlight six major interrelated coastal vulnerabilities including: (1) reduction of clam and clam habitat quantity and quality, (2) reduction in chiton quality and quantity, (3) harmful expansion of sea otter populations, (4) overharvest and pollution of black seaweed habitats, (5) overharvest of salmon and decrease in salmon rearing areas, and (6) decrease in quantity of deer. Spatial trends and possible solutions are discussed.