NCCOS Mapping: Characterizing Submerged Lands Around Naval Base Guam, Mariana Islands, 2016-01-11 to 2022-05-13 (NCEI Accession 0292018)

This data package contains information and maps showing the geology and biology of select submerged lands (0 to 50 meters deep) around Navy Base Guam (NBG) and Haputo Ecological Reserve Area (ERA) Guam, Mariana Islands. This information and maps were developed using benthic information from underwater photographs, environmental predictor variables derived from satellite imagery and bathymetry, and machine learning modeling approaches. From this process, two types of map products were created. The first type describes the spatial distribution of 7 substrate and 12 biological cover types, where each grid cell denotes the probability that a given habitat is present (0 to 100%). The second product was a classified map depicting the 7 most common combinations of substrate and cover types. The performance and accuracy of these products were evaluated by local experts and by using an independent of underwater photographs. The overall accuracy of the classified map was 86.6%. The substrate and cover predictions had little bias (𝑥𝑥̅ error = ‐2% ±1% SE), good to excellent ability to discriminate between presences and absences (𝑥𝑥̅ area under the curve = 0.86 ±0.02 SE) and explained over a quarter of the variation in the data (𝑥𝑥̅ percent deviance explained = 26.9% ±5.1 SE).

In Haputo ERA, ‘Pavement, Mixed Algae’ was the most abundant habitat type, comprising 54.5% (1.1 km2) of the area. The largest, continuous patches were located on the forereef along the coastline. Live coral was distributed throughout the ERA, with encrusting corals being most prevalent. No seagrass or mangroves were present. Around NBG, ‘Sand, Bare’ was the most abundant habitat type, comprising 42.3% (8.2 km2) of the area. The largest, continuous patches were in the eastern portion of Outer Apra Harbor, including Sasa Bay and south of Cabras Island. Live coral was common and most prevalent from San Luis Point around Point Udall to Acapa Point. Halodule uninervis seagrass was only documented outside Apra Harbor at 2 sites approximately 500 m north of Acapa Point. Mangroves were found only in nearshore areas in Sasa Bay and Inner Apra Harbor. No Endangered Species Act (ESA) protected corals or nuisance species (i.e., C. vieillardi) were photographed in either project areas. One crown of thorns sea star was photographed in Haputo ERA. The prevalence of coral bleaching, COTS scarring and marine debris were low (<1%, 0% and <4%, respectively). Theses maps mark the first time that these locations have been mapped since 2010, providing an updated inventory of marine resources and new baseline for future monitoring and management decisions in the region.