NOAA Tests Habitat Mapping Capabilities in U.S. Virgin Islands

Back Story

Figure 1. Map of study area (Flat Clay) showing the location of UNH dive sites, and the location of NOAA tow fish transects. Image provided by NOAA.

Figure 1. The U.S. Virgin Islands Flat Cay study area map shows the location of UNH dive sites, and the location of NOAA towfish transects. Image provided by NOAA.

Exploring areas at the bottom of the sea – called ocean benthic habitats – provides important insight into underwater life that scientists and policymakers alike can use to inform everything from conservation to energy planning.

Mapping these deep, complex habitats is difficult and requires data from multiple sources to create. To improve this capability, the National Oceanic and Atmospheric Administration and the U.S. Geological Survey partnered in 2014 to research the effectiveness of Experimental Advanced Airborne Research (EAARL-B) LiDAR systems by creating seafloor habitat maps south of St. Thomas, U.S. Virgin Islands.

These maps have primarily used seafloor complexity metrics derived from depth at coarser spatial scales than the LiDAR data can support. NOAA is investigating whether LiDAR waveforms can get similar seafloor complexity information at finer spatial scales.

The Strategy

In September 2016, field operations south of St. Thomas near Flat Cay were led by Tim Battista and Bryan Costa of NOAA, in partnership with Dr. Jenn Dijkstra and Kristen Mello from the University of New Hampshire (UNH) Center for Coastal Ocean Mapping.

NOAA operations focused on collecting habitat information in deeper (15-25 m) locations and over broader areas than EAARL-B LiDAR operations. The team used Boston Engineering’s 760 V-Wing towed depressor to collect photos and videos of the seafloor at an altitude of 1-4 m. Because of its stability, the 760 V-Wing provides increased reading accuracy along with the ability to carry a variety of research technology. The V-Wing towfish was outfitted with:

  • Green lasers
  • 1 Sensus Ultra depth sensor
  • 1 HD seaviewer camera (for real-time video)
  • 2 GoPro HERO 4 cameras

    UNH divers (left)collecting habitat information in a 10x10 m area. The towed depressor V-Wing (right) is modified to collect videos and create photomosaics of the seafloor in deeper locations and over broader areas. Photos provided by NOAA.

    Figure 2. Left: UNH divers collect habitat information in a 10×10 m area. Right: The V-Wing towed depressor is modified to collect videos and to create photomosaics of the seafloor in deeper locations and across broader areas. Photos provided by NOAA.

The Impact

This field team will process its collected data to create photomosaics of the seafloor. After the mosaics are finalized, researchers can extract habitat functional groups, habitat IDs (to the lowest taxonomic level), and rugosity values. Oregon State University will apply machine learning techniques that it developed to explore correlations among these habitat metrics and the LiDAR waveforms. Results will be submitted to peer-review journals for publication. NOAA, OSU, UNH, and other scientists can then use results to better understand and improve benthic habitat mapping.