National Marine Sanctuary of American Samoa Resilient Despite Climate Change
By Rachel Plunkett
A tropical paradise in the Pacific—National Marine Sanctuary of American Samoa—offers a unique opportunity for researchers to observe ocean and coral reef ecosystems that are largely considered to be remote, yet still experience pressure from humans. NOAA has just released the first condition report for the sanctuary since it was expanded a decade ago. In the report, NOAA states that the overall condition of sanctuary resources is good, however there is evidence that climate change effects, such as coral bleaching and coastal erosion, are threatening habitats, resources, and ecosystem services.
Located in the heart of Polynesia, National Marine Sanctuary of American Samoa covers six protected areas, including 13,581 square miles of nearshore coral reef and offshore open ocean waters across the Samoan Archipelago. It was formerly known as Fagatele Bay National Marine Sanctuary, established in 1986 to protect 0.25 square miles of coral reef habitat in Fagatele Bay. In 2012, the sanctuary expanded to include five additional units: Fagalua/Fogama’a, Aunu’u, Ta’u, Swains Island, and Muliāva. The sanctuary is known for its coral reefs, but also includes mesophotic coral ecosystems, pelagic and deep ocean floor habitats, hydrothermal vents, and maritime heritage resources. It offers a refuge for humpback whales, sea turtles, reef sharks, and seabirds.
The small islands that compose American Samoa are not just unique because of their stunning natural environment, but also because of Fa’a Samoa—the communal Samoan lifestyle—and the cultural traditions, language, and values that thrive in these islands. Healthy ocean resources are imperative to preserving the traditional way of life in American Samoa.
NOAA uses sanctuary condition reports as a standardized tool to assess the status and trends of national marine sanctuary resources and ecosystem services. The major findings within this report focus on the condition and trends in water quality, habitat, living resources, maritime heritage resources, and ecosystem services from 2007–2020. This condition report will inform the upcoming management plan review process for National Marine Sanctuary of American Samoa by helping to identify priority issues that need to be addressed.
Increasing Ocean Temperatures
Since the 2007 condition report was released, ocean temperatures have continued to increase, and rising sea levels are now affecting marine ecosystems across the sanctuary. These direct impacts from climate change are measurable, and are expected to increase over the next century.
Most notably, elevated water temperatures cause coral bleaching, which is a stress reaction of coral animals in response to warmer water temperatures. When water is too warm, corals expel the colorful algae living in their tissues, which is their main food and energy source. This causes the coral to turn completely white. If corals remain bleached for a prolonged time, the coral animal may die. So far, most coral communities in National Marine Sanctuary of American Samoa have been able to recover from bleaching events in 2015, 2017, and 2020, but coral bleaching is predicted to occur much more frequently as sea surface temperatures continue to rise.
“In the past, the reefs here experienced mass coral bleaching maybe once a decade,” says Val Brown, research coordinator at the sanctuary. “With warming ocean temperatures, there have been three events in the past seven years. It takes time for reefs to recover. If this pattern continues, our reefs may not be able to keep up.”
Many coral diseases have also been linked to increasing ocean temperatures in combination with the presence of pollutants and bacteria in the water. This is a growing concern for resource managers in National Marine Sanctuary of American Samoa as we see coral diseases spread across shallow coral reefs on the other side of the U.S. in the Western Atlantic.
The close proximity of the Futiga Landfill to Fagatele Bay and Fagalua/Fogama’a and the sewage outfall in Aunu'u raised concerns about the possibility of pollutants leaching into the nearby waters. The report finds that even though some land-based pollutants are reaching the bay, the water quality of the system is relatively good.
Every organism within an ecosystem has a role to play, and scientists classify organisms into different categories that explain those roles. Foundation species are those that create or maintain habitat, such as stony reef-building corals, and keystone species are those whose diet or behaviors have a major impact on all other species within the ecosystem, such as reef sharks. Changes in foundation and keystone species within a marine environment can cause an ecosystem to shift out of balance. The report looked at the abundance and condition of several important species—from the bottom of the food chain to the top—and determined that the status of keystone and foundation species within the sanctuary is mixed.
While foundation species such as coral and coralline algae have proven resilient, keystone species such as large parrotfish, surgeonfish, and sharks are reportedly showing up in lower abundances across sanctuary waters. This is concerning because large predators such as sharks help keep the food web structure in balance by eating smaller fish, and large herbivorous fish (e.g., parrotfish) eat algae off the reef, keeping the reef healthy and leaving space for more corals to grow.
Faisua, or giant clams (Tridacna spp.), were evaluated in the report as a focal species. Not only are they beautiful to look at—they are socially and ecologically important in American Samoa. The shells of clams have traditionally been used for tools and ornamentation, and clam meat is a popular food item. The condition report shows that the abundance of this focal species across the sanctuary is low and populations have not yet recovered after a steep decline from 1996–2006.
Fa’a Samoa emphasizes reciprocity, rather than the individual accumulation of resources and wealth, and in American Samoa, the majority of lands are communal. In Samoan society, land tenure is an integral part of social organization and is tied to both the kinship system and village organization. Aiga (families) derive their rights to land use through their connection to their founding ancestor and select a matai (chief) to serve as trustee of family communal land and spokesperson in the saofa’iga a le nu’u (village council of chiefs). The sanctuary maintains great respect for Fa’a Samoa, and consults with village councils when it comes to making decisions about local resources.
NOAA co-manages the sanctuary with the government of American Samoa and works closely with communities adjacent to the sanctuary. This condition report includes community voices and perspectives, and highlights the reciprocal relationship between humans and the ocean.
“Samoan history is based on oral history, where interpretation is taken word for word, and one must understand the past history to prepare for future challenges,” noted High Chief Dr. Alo Stevenson, Eastern District governor. “I'm so glad that in your role as the marine sanctuary, you take on this function to establish this for the future of our generations.”
As Samoans rely heavily on the ocean for recreational activities, subsistence harvesting (e.g., for family, ceremony, sharing, gifting, and bartering) and coastal protection, community involvement in future resource management decisions is imperative.
Community members are especially concerned about the combined impacts of rising sea levels and local land subsidence (sinking), which is eroding coastlines and threatening community resources essential to Fa’a Samoa. Since coral reefs provide a buffer that protects our coasts from waves, storms, and floods, protecting and supporting healthy reefs in National Marine Sanctuary of American Samoa is more important than ever before.
Education and outreach efforts about the threats that sanctuary resources are facing have engaged a wide range of audiences and partners at local, regional, national, and international scales.
Managing Resources in an Uncertain Future
The assessment period for this condition report was from 2007 to 2020. The report, published by NOAA, will inform the upcoming management plan review process for National Marine Sanctuary of American Samoa by identifying key issues and gaps in knowledge where sanctuary management efforts should be allocated in the future. This information will guide sanctuary staff and partners as they embark on a process to review and update the 2012 management plan.
This continuous management cycle, including monitoring, planning, and implementation, is essential to managing resources in areas such as National Marine Sanctuary of American Samoa, which are susceptible to coral bleaching and other devastating impacts from climate change. This is especially true when these resources are not only tied to the health of entire ecosystems, but also intrinsically tied to the way of life for Samoan people.
"E le sua se lolo i se popo e tasi—it takes more than one to successfully complete a task,” said Superintendent Atuatasi Lelei Peau. “As we embark on the management plan review, the sanctuary will rely on the support and participation of our community, local, and federal partners to successfully complete this major undertaking.”
Rachel Plunkett is the writer/editor for NOAA's Office of National Marine Sanctuaries