Climate Change and Ocean Acidification
American Samoa

close up view of Coral bleaching
Coral bleaching can occur as the result of increased sea surface temperature and bleaching events can lead to coral mortality. Credit: Wendy Cover, NMSAS, NOAA

Why is it a concern?

Global and regional changes to the marine environment associated with climate change may have significant consequences for coral reef ecosystems and coastal communities relevant to the National Marine Sanctuary of American Samoa (NMSAS).  Regional physical changes to the marine environment include climate variability, sea level rise, ocean circulation patterns, and ocean acidification. These changes combined with anthropogenic stressors may produce cumulative impacts on biodiversity and ecosystem health including changes in physiology, phenology, population connectivity, and species range shift.

Coral reefs are particularly vulnerable to climate change and can be impacted by coral bleaching, ocean acidification, increased storm occurrence and sea level rise. Coral bleaching can occur as the result of prolonged exposure of the corals to increased sea surface temperatures. Bleaching events can lead to coral mortality and have lasting effects on coral ecosystem community structure. Ocean acidification is also a concern for reef building corals and other organisms with calcium carbonate structures. Increasingly acidic ocean water may diminish an animal's normal ability to build a shell or coral structure and can impact growth rates. Sea level rise brings with it threats of habitat loss, accelerated coastal erosion, and changes in water quality and light penetration.

Overview of Research

Research conducted by Sanctuary scientists and partners provides critical information to address existing and emerging resource conservation and management issues. The Overview of Research highlights some, but not necessarily all, of the research activities completed or ongoing at the Sanctuary.

Project Name PI and contacts Links

Climate Impacts to the Nearshore Marine Environment and Coastal Communities: American Samoa and Fagatele Bay National  Marine Sanctuary

Brian Cheng and Emily Gaskin

SCLERA (Samoan Coral Local Environmental Resistance Atlas)

Tom Oliver, University of Hawaii / Coral Reef Ecosystem Division. 

Coral resistance to bleaching.

ASRAMP (American Samoa Reef Assessment and Monitoring Program)

NOAA/NMFS/Coral Reef Ecosystem Division, Honolulu. Rusty Brainaird, Division Chief.
(Oceanographic properties; accretion/acidification study; coral cores.)

Historical Climate Study

Rob Dunbar, Stanford University

No URL available. Coral cores from Big Momma in Ta'u. Will elucidate long-term climate patterns and changes in growth.

Coral Reef Watch

NOAA.  Mark Eakin, Chief.

Provides online predictions of coral bleaching for the region.


Science Needs and Questions

The best available science is used by Sanctuary scientists and managers working to address priority resource conservation and management issues. As priorities change and new issues emerge, each Sanctuary develops new science needs and questions and works with partners to address them.

  • Which coastal areas will be affected by sea level rise the soonest?
  • How will sea level rise affect coastal erosion?
  • Which species (marine and terrestrial) are likely to be impacted by increases in sea level?
  • What options are available to managers to address and potentially mitigate sea level rise and ocean acidification in the Sanctuary?
  • Will sea level change impact deep water photosynthesizing organisms?
  • How could ocean acidification affect the ecosystem as a whole?
  • Which calcifying organisms are most severely affected by acidification?
  • What characteristics of a specific area confer resistance or susceptibility to bleaching?
  • How widespread are bleaching events in the sanctuary?
  • How far in advance can bleaching events be predicted using currently available tools?
  • How do bleaching events affect the ecosystem as a whole?

Education and Outreach Material

Office of National Marine Sanctuaries Climate Change Website:


Cheng, Brian and Emily Gaskin. 2011. Climate Impacts to the Nearshore Marine Environment and Coastal Communities: American Samoa and Fagatele Bay National  Marine Sanctuary. Marine Sanctuaries Conservation Series ONMS-11-05. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Office of National Marine Sanctuaries, Silver Spring, MD. 71pp.

Elevated Ocean Temperature:
Fagatele Bay National Marine Sanctuary: Research

Fenner, D. 2004. Summer coral bleaching event, 2004, on Tutuila, American Samoa. Report to Department of Marine and Wildlife Resources, American Samoa. 4 pp.

Goreau, T.J, Hayes, R.L. 1994. A survey of coral reef bleaching in the South Central Pacific during 1994. A report to the Coral Reef Initiative, U.S. Dept of State. 118 pp.

Natural History Guide to American Samoa (Marine Environment)

U.S. Geological Survey: U.S. Coral Reefs – Imperiled National Treasures