In 2004, shallow-water benthic habitats were mapped in Saipan Lagoon, Commonwealth of the Northern Mariana Islands. Since then, habitats in the lagoon have likely changed because of coral bleaching events and recent typhoons. Local resource managers requested an updated map to help better understand these habitat changes and to help inform their monitoring and management decisions. In response, we created an updated benthic habitat map for areas shallower than 30-meters inside the lagoon.
Why We Care
Shallow-water benthic habitats in Saipan Lagoon, Commonwealth of the Northern Mariana Islands (CNMI) have been stressed by recent typhoons and bleaching events. In March 2015, an El Niño event began in the equatorial Pacific, resulting in increased storm activity in the region and substantial coral bleaching. Estimates suggest that approximately 85 percent of staghorn corals in Saipan Lagoon have died due to bleaching since 2013. In August 2015, Typhoon Soudelor swept through the Pacific, directly hitting Saipan. Preliminary estimates indicate that some coral reefs were severely impacted by the storm.
The combination of these stressors and other human-caused threats has most likely changed the composition of habitats in Saipan Lagoon. Local resource managers from CNMI’s Bureau of Environmental and Coastal Quality requested that the existing habitat map—produced by the University of Guam in 2004—be updated to better understand these and other habitat changes over the last decade. This updated map is being used to inform monitoring and management decisions in the lagoon, including updating the Saipan Lagoon Use Management Plan.
What We Did
We used multispectral imagery to produce an updated, shallow-water benthic habitat map for Saipan Lagoon. A new satellite image of the lagoon was collected in February 2016. This remote sensing data was used to develop a new habitat map. The resulting habitat map depicts the distribution of key biological and geomorphological habitats using a classification scheme comparable to Houk and van Woesik, 2008 (published in Marine Ecology Press Series, 2008: 356: 39-50). We collected underwater photos and videos in partnership with local experts in CNMI. These photos and videos were used to improve the quality of the habitat map. A separate accuracy assessment was conducted to independently assess the thematic accuracy of the resulting habitat map. Local experts from the jurisdictional community evaluated the habitat map products before they were finalized. The final habitat map and associated products are publicly available for download and for viewing online (see Data Collections below).
Benefits of Our Work
The products developed during this project provide a critical spatial framework to better understand benthic habitat changes over the last decade in Saipan Lagoon. Future projects or management actions in Saipan Lagoon will benefit greatly from the updated imagery, habitat map, and underwater photos and videos compiled during this project. These data sets will inform decisions about sampling, permitting activities, management of marine protected areas (MPAs), land-based sources of pollution, fishery regulations, climate change, and scientific research.