Pacific Islands-Alaska CASC Collaboration


Steep-sided, snowy mountains run straight down to a lake
Turner Lake, south of Juneau, Alaska. (Photo: Molly Tankersley)

Steep watersheds with dramatic environmental gradients are familiar features of both the Pacific Islands and Southeast Alaska, and both locations are experiencing significant alterations to watershed ecosystems and environmental processes due to climate change.

On high Pacific Islands, the holistic ecosystem view linking coastal watersheds to the ocean is dubbed “ridge to reef” (R2R) while Alaska terms it “icefield to ocean” (I2O). Regardless of terminology, both regions are experiencing impacts through terrestrial, freshwater, and nearshore marine ecosystems via the movement of water, energy, biota, and nutrients. Human communities in both regions depend on the cultural and ecosystem services provided by these linked land-to-coastal marine systems.



A view down a steep sided, U-shaped valley to the ocean
Kalalau Valley on Kauaʻi, Hawaiʻi (Photo: Jon Price)

The Alaska and Pacific Islands Climate Adaptation Science Centers have joined forces to address these similar local challenges together, in a collaboration unique to the CASC network.

Scientists from each region are teaming up to perform cross-regional research, cultural engagement, and synthesis, developing a variety of forums for scientists, managers, and students to jointly explore these systems and exchange knowledge as a means to support community-based climate adaptation.


PI: Ryan Bellmore
Streamflows are changing in both Hawaiʻi and Southeast Alaska, impacting riverine ecosystems and the marine ecosystems into which rivers flow. This project examines how changes in sequence affect nutrient cycling, how the timing of high and low-flow in rivers and streams will impact surrounding ecosystems, and how the human dimension is impacted by these changes.

PI: Tim Grabowski
The overall goal of the proposed project is to develop a multidisciplinary team to evaluate the effect of flow alteration on R2R and I2O watersheds. This project will evaluate the effects of annual variability in flow conditions on the growth and survival of  invasive armored suckermouth catfish in Hawaiian streams, and compare/contrast findings to those of a complementary study linking hydrology to freshwater salmon growth in southeast Alaska.

PI: Jeff Falke
Changing streamflow patterns in Southeast Alaska alter nutrient cycling, sediment transport, and species composition. How this will impact salmon growth is unclear. Understanding the influence of flow regimes and other environmental factors on fish population dynamics has relevance for the conservation and management of fish populations, as well as the ecosystem as a whole.

PI: Yinphan Tsang
Changes to streamflow patterns and precipitation impact river, estuary, and coastal ecosystems that host native aquatic species in Hawaiʻi. PI-CASC researchers will work collaboratively with researchers in Alaska to expand the capacity in addressing climate impacts on aquatic ecosystems from the mountains to the sea. This project will build upon existing efforts to assess the impact of changing climate on nine groups of native aquatic species, applying the concept of Ridge-to-Reef and using tools to prioritize conservation efforts for Hawaiʻi aquatic ecosystems.

PI: John Burns
Nearshore marine environments provide ecosystem services such as sustenance, coastal protection, critical fish habitat, economic value through recreation and fisheries, medicinal products, and cultural importance and traditional activities. Using innovative 3D mapping technologies, researchers will examine how organic matter and nutrient flux influence the biology and ecology of coral reefs that are impacted by freshwater discharge, highlighting how patterns in stream flow alter land-to-ocean materials flux and productivity in marine habitats.

PI: Rick Lader
Drought and precipitation extremes are of significant concern to natural resource management in both Hawai‘i and Southeast Alaska. This project will make existing CASC-supported numerical modeling results more accessible for resource managers who experience barriers to incorporating climate change projections into their planning.

PI: Janet Curran
Different flood‐producing mechanisms may not change uniformly in a future climate, and floods may increase or decrease in magnitude or change in seasonal timing. To understand the effects of climate change on floods and how ecosystems and human communities may be affected by flood‐related changes, this project will look at the main flood‐producing mechanisms in high-elevation basins in Southeast Alaska and Hawaiʻi.

Pacific Island and Alaska Climate Adaptation Science Center Leadership

Mari-Vaughn Johnson

Mari-Vaughn Johnson
PI-CASC Federal Director

Darren Lerner

Darren Lerner
PI-CASC University Director

Steven Gray

Steven Gray
AK CASC Federal Director

Scott Rupp

Scott Rupp
AK CASC University Director

Illustration with two halves showing mountains down to coastal ocean with differences between Pacific Islands and Alaska