Impacts of the 2008 Kasatochi Volcano Eruption on Terrestrial and Marine Ecosystems

Alaska is noteworthy as a region of frequent seismic and volcanic activity. The region contains 52 historically active volcanoes, fourteen of which have had at least one major eruptive event since 1990. Despite the high frequency of volcanic activity in Alaska, comprehensive studies of how ecosystems respond to volcanic eruptions are non-existent. On August 7, 2008, Kasatochi Volcano, located in the central Aleutian Islands, erupted catastrophically, covering the island with ash and hot pyroclastic flow material. Kasatochi was an annual monitoring site of the U.S. Fish and Wildlife Service, Alaska Maritime National Wildlife Refuge (AMNWR), thus features of the island’s terrestrial and nearshore ecosystems were well known. In 2009, the U.S. Geological Survey, AMNWR, and the University of Alaska Fairbanks, with funding support from the North Pacific Research Board, initiated long-term studies to better understand the effects of the eruption and the role volcanism plays in structuring ecosystems in the Aleutian Islands, a volcano-dominated region with high natural resource values.

Kasatochi Volcano in July 2008 (left) and then in October of 2008 (right). The volcano erupted August 7, 2008.

Pre-eruptive Kasatochi

Kasatochi is a small stratovolcano located in the central Aleutian Islands. Prior to the eruption it was about 3 km in diameter, 300 m high, and in the center was a steep-walled caldera with a small lake. By the nature of its water-filled caldera and steep, verdant slopes, Kasatochi was one of the most picturesque of the Aleutian Islands. Before the 2008 eruption, it was steep, rugged and it’s vegetation was dense, low-growing and dominated by many species of grasses and forbes making it similar to other Aleutian Islands. What set Kasatochi apart was the diversity and abundance of seabirds that nested there each summer. Most notably, Kasatochi supported a colony of about 250,000 least and crested auklets, one of only seven such colonies in the Aleutian chain. The large numbers of seabirds attracted a variety of avian predators such as bald eagles and peregrine falcons. Kasatochi was also notable in that it supported a rookery of the endangered Steller sea lion.

As the photographs of Kasatochi taken in 2008 suggests, life on the island appears to have been destroyed by the August 7 eruption. During the summer of 2009, we initiated a study to understand how Kasatochi had changed over the winter and to discern the initial fate of the island’s terrestrial and marine plants and animals.

Research Objectives

Our long-term goal is to examine how terrestrial, nearshore, and marine ecosystems at and around Kasatochi respond to the cataclysmic eruption of August 7, 2008. This is a unique opportunity to examine how volcanism and geomorphologic processes influence ecosystem succession on a remote maritime island through the integration of various scientific disciplines. Kasatochi provides a real-world laboratory to examine island biogeographic theory and the factors that influence dispersal and re-settlement of plant, invertebrate and vertebrate species.

Post-eruption Research in 2009

During the summer of 2009, teams of geologists, botanists, ornithologists, and marine ecologists visited Kasatochi and nearby islands four times to document the impacts of the eruption and establish baseline conditions from which long-term comparisons will be made. The teams were supported in the field by the U.S. Fish and Wildlife Service’s vessel, the M/V Tiglax. The teams set up equipment such as seismometers, time lapse cameras and bird song meters. They also established permanent transects and plots for sampling and for making detailed measurements.

Location of Kasatochi Island in the west-central Aleutian Islands of Alaska, with nearby islands and extent of ash fall from the August 7, 2008 eruption. (click on map for a larger view)

Funding support for the Kasatochi Project provided by: