Benthic Habitat Data

Bathymetry

Zipped data files contain 1) grid data file (GMT or ASCII), 2) high-res JPG of image, and 3) explanatory metadata text file (identical to linked file listed below).

20m grid data
5m grid data

Zipped data files contain 1) Arc ASCII file, 2) layer (.lyr) file for symbology, 3) high-res JPG of image, and 4) explanatory metadata text file (identical to linked file listed below).

5m grid data files

Northwest Hawaiian Islands:                                Pearl and Hermes Atoll

[ Bathymetry | Backscatter| Optical Validation | Geomorphology ]

Optical Validation

The collection and analysis of photographic data to ground truth and interpret multibeam data layers with the goal of characterizing seafloor habitats.

Coral Cover Map

TOAD map for Pearl and Hermes Atoll.
Click thumbnail map to view a high-resolution JPG.

The map above shows percent cover values of scleractinian coral derived from classified photos and videos collected at Pearl and Hermes Atoll in 2002, 2003 and 2004. Each point represents an analyzed video frame or photo. Note that the percent classes are unevenly sized to better display this relatively low-abundance bottom type.

Descriptions of optical data products.

Download: Accessory Files

The optical data are classified by substrate type, type of live growth on bottom, geomorphic zone, and the size and abundance of holes in the substrate. Although what we show here is the percentage of coral, the shapefiles contain data on all those categories, enabling users to map the occurrence of any combination of characteristics that are included in the classification scheme. (See sidebar for shapefiles.)

Mobile Fauna Map

TOAD map for Pearl and Hermes Atoll.
Click thumbnail map to view a high-resolution JPG.

Descriptions of optical data products.

Download: Accessory Files

The map above shows total fish biomass from Towed Optical Assessment Device (TOAD) videos collected at Pearl and Hermes Atoll in 2003 and 2004.  Optical data from 2002 were exclusively still photographs which were not suitable for mobile fauna classification.  Each point represents a thirty second video interval centered on a location derived from points classified in the optical validation maps.  Note that size classes are unevenly distributed to minimize in-class variability.


The mobile fauna data contain biomass estimates as well as the numbers of fish which make up that total biomass.  Although the mobile fauna maps present biomass, fish numbers can be found in the underlying shapefiles (see layer file description for instructions).  This enables users to obtain a more detailed understanding of the distribution of fish assemblages.  Benthic classifications associated with these data can be downloaded with the other Optical Validation data.

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