Coral Reef Resilience to Climate Change in the Commonwealth of the Northern Mariana Islands: Field-based Assessments and Implications for Vulnerability and Future Management

Jeffrey Maynard, Steven McKagan, Laurie Raymundo, Steven Johnson, Gabby N. Ahmadia, Lyza Johnston, Peter Houk, Gareth J. Williams, Matt Kendall, Scott F. Heron, Ruben van Hooidonk, Elizabeth Mcleod, Dieter Tracey, Serge Planes
Posted on: 7/18/2022 - Updated on: 11/08/2023

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Coral reefs are sometimes called “rainforests of the sea” because of their immense biological diversity and economic value. While coral reefs are sensitive to changes in their environment such as altered temperature or pollution, some reefs are more resilient, or able to recover from disturbance more quickly, than others.

The overarching objective of this project was to gather information on coral reef resilience and vulnerability to climate change that could inform coastal management decision-making in the Commonwealth of the Northern Mariana Islands (CNMI). Scientists collaborated with local managers to survey reefs at 78 locations throughout the CMNI and evaluate indicators of resilience, such as numbers of juvenile corals and plant-eating fish. Their findings highlight priority sites for management action and identify which management actions (e.g., fisheries regulation, pollution reduction, reef restoration and monitoring) will best support natural resilience at each site. Local managers are currently using the results to inform and improve the effectiveness of their coastal management planning.

Reducing coral reef vulnerability to climate change requires that managers understand and support the natural resilience of coral reefs. We define coral reef resilience as: the capacity of a reef to resist and/or recover from disturbance given its probable exposure regime, and maintain provision of ecosystem goods and services. Spatial variation in exposure to disturbance and the resilience of reefs in the face of those disturbances will determine the fate of coral reefs within management jurisdictions. This project sought to:

  1. Undertake ecological resilience assessments in the Commonwealth of the Northern Mariana Islands (CNMI), which is in the west Pacific near Guam
  2. Collaboratively develop a decision-support framework with local manager partners for resilience-based management

Between 2012 and 2014, our team surveyed 78 sites along the 30-foot contour of the fringing reefs surrounding the most populated islands in CNMI: Saipan, Tinian/Aguijan, and Rota. These surveys, and complementary analyses using data from environmental monitoring satellites and computer models, included measurements and assessments of variables that are ‘indicators’ of the processes that underlie reef resilience (e.g., recruitment of new corals and the control of macroalgae on reefs by herbivory).

The final results are scores for relative resilience potential that resulted in our ranking the survey sites within and among the islands from high to low resilience. We also assessed two proxies of anthropogenic stress: land-based sources of pollution (e.g., nutrients and sediments) and accessibility due to wave exposure (e.g., fishing access). We found resilience potential to vary greatly within and among islands and set 7 custom criteria within a decision-support framework that identifies sites that warrant management attention.

This project represents globally relevant progress in the novel approach of using resilience assessments to inform management decision-making. Uniquely, the project was undertaken highly collaboratively with local managers in CNMI that are using the results to inform resilience-based management and management planning.


Maynard, J., McKagan, S., Raymundo, L., Johnson, S., Ahmadia, G.N., Johnston, L., Houk, P., Williams, G.J., Kendall, M., Heron, S.F., van Hooidonk, R., Mcleod, E., Tracey, D., Planes, S. (2015). Assessing relative resilience potential of coral reefs to inform management. Biological Conservation, 192: 109–119.

Affiliated Organizations

The USGS is a science organization that provides impartial information on the health of our ecosystems and environment, the natural hazards that threaten us, the natural resources we rely on, the impacts of climate and land-use change, and the core science systems that help us provide timely, relevant, and useable information.

Established in 2012, the Pacific Islands CASC (PI-CASC) provides regionally-relevant scientific information, tools, and techniques to resource managers and communities in Hawai'i and the U.S.-Affiliated Pacific Islands.

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