From land to sea: How will hydrologic regime shifts influence aquatic ecosystems in Southeast Alaska and Hawaiʻi?

The flow of streams is changing in both Hawaiʻi and Southeast Alaska, impacting riverine ecosystems and the marine ecosystems into which rivers flow. In both regions, streams are expected to experience more dramatic low water conditions overall, interspersed with larger, and potentially more frequent, high-flow events in the coming decades. These predicted changes in flow regime are likely to influence the magnitude, timing, and composition of materials fluxes to nearshore ecosystems in both Alaska and Hawai‘i.

This collaborative study will examine how patterns of stream flow in Alaska and Hawai‘i influence land-to-ocean, or ridge-to-reef, linkages, including how materials, invertebrates, and fish are exported at catchment outlet streams in both Juneau, Alaska, and Hilo, Hawai‘i. In both locations, this project will examine how the sequence of high- and low-flow events and preceding conditions influence material fluxes (i.e., instead of focusing on individual high/low flow events); how the timing of high and low flow in rivers and streams will impact surrounding ecosystems; how communities are impacted by these changes; and how these changes may be expressed differently in Southeast Alaska versus Hawai‘i. This information is essential for informing and developing watershed management plans to improve near-shore water quality and food webs.

Using the information collected from streams in both locations, the project team will construct a model that can be used to predict the effects of stream flow regimes on the magnitude and composition of material fluxes. The model will aim to inform how future streamflow conditions may influence ridge-to reef linkages in each stream and help researchers generate hypotheses that could be tested across a broader range of streams which may already represent future conditions.