Hard and Soft Bottom Seafloor Substrate Map Derived from an Unsupervised Classification of Gridded Bathymetry Derivatives for the NOAA Habitat Blueprint West Hawaii Focus Area

Hard and soft bottom seafloor substrate data and maps for the NOAA Habitat Blueprint West Hawaii Focus Area (WHFA) in the Main Hawaiian Islands. Cell values in the raster datasets reflect whether the seafloor is hard bottom or soft bottom based on an unsupervised classification run using ArcGIS software with the Spatial Analyst extension. The classifications are based on bathymetry, acoustic derivatives and verified using seafloor optical data.

The seafloor substrate map and associated data are accessible online via the Pacific Islands Benthic Habiat Mapping Center (PIBHMC) website at www.soest.hawaii.edu/pibhmc.

Prepared by the NOAA Coral Reef Ecosystem Program (CREP) and funded by the NOAA Coral Reef Conservation Program (CRCP) and NOAA Habitat Blueprint, the maps include but extend beyond the boundaries of the CRCP-designated West Hawaii priority site.

The data were derived in support of CRCP goals to map all U.S. Coral Reef Ecosystems by developing high-resolution benthic maps to characterize priority reefs and associated habitats. This derivative of bathymetry provides a GIS layer that may be used for benthic and essential fish habitat characterization, and for the study of geologic features. By combining the dataset with bathymetry, other derivatives, and in-situ data, they collectively compose benthic habitat maps which are designed to be used to understand and predict benthic habitats for different organisms that inhabit coral reef ecosystems.

The hard and soft seafloor map is being used for long-term ecosystem monitoring, to guide future ground-truthing operations and to identify coral-rich environments and can be used in the development of actionable policies, plans and management practices.

Suka, R., J. Rooney. 2017. Acoustic Characterization of Mesophotic Coral Reef Ecosystems of West Hawai¿i. U.S. Dep. Commer., NOAA Tech. Memo., NOAA-TM- NMFS-PIFSC-61, 31 p. https://doi.org/10.7289/V5/TM-PIFSC-61.

This is a preliminary product developed by the NOAA Coral Reef Ecosystem Program (CREP) and the methods used to generate the map are planned for publication as a NOAA Technical Memorandum.

The bathymetry and optical data collected by NOAA CREP for this project along with the derivative datasets generated by NOAA CREP, including coral cover, slope, rugosity, Bathymetric Position Index Zones, Bathymetric Position Index Structures, and Dominant Benthic Structure and Cover Habitat, are documented and hosted separately on the PIBHMC website at www.soest.hawaii.edu/pibhmc.

The hard vs soft substrate designation is applied by performing an unsupervised classification on bathymetry data using the Iso Cluster classification tool in ArcGIS. This classification produces two classes, representing hard and soft substrate.

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

NOAA Habitat Blueprint West Hawaii Focus Area, Hawaii, Main Hawaiian Islands

Not applicable

Not applicable

NOAA Coral Reef Ecosystem Program (CREP) Data Sharing Recommendations, version 9.0 updated August 12, 2015:

CREP welcomes the opportunity to collaborate on research issues contributing to the scientific basis for better management of marine ecosystems. CREP has a very diverse set of field activities that generates large volumes of data using an array of data collection protocols.

The following recommendations are for your consideration as you use this data:

1) Data analyses should take all field exigencies into account. The most effective way to do this would be active collaboration with CREP principal investigators.

2) In all presentations, product releases, or publications using data generated by CREP, proper acknowledgement of both CREP and the individuals responsible for data collection is expected. Citing the DOI (if available) is preferred, a non-DOI example is listed below.

3) If you collect or generate data for the same study areas, CREP requests that you share relevant information on complimentary data collections.

4) Those receiving data are strongly urged to inform the CREP Data Management Team of any errors and discrepancies that are discovered during the course of using these data. They are further urged to bring to the attention of the Team all problems and difficulties encountered in using these data. This information is necessary in order to improve the collections and to facilitate more efficient and economical data processing and retrieval. The users are asked to supply copies of any missing data that may be located, and to provide information as to significant subsets and special aggregations of data that are developed in using the material provided.

Example citation:

"This publication makes use of data products provided by the Coral Reef Ecosystem Program (CREP), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), with funding support from the NOAA Coral Reef Conservation Program (CRCP) and NOAA Habitat Blueprint. The analysis and interpretations presented here are solely that of the current authors.”

Data can be accessed online via the Pacific Islands Benthic Habitat Mapping Center website at https://www.soest.hawaii.edu/pibhmc/pibhmc_mhi_haw.htm

None

These data are not to be used for navigation purposes.

Please cite NOAA Coral Reef Ecosystem Program (CREP) when using the data.

Suggested citation:

Coral Reef Ecosystem Program; Pacific Islands Fisheries Science Center (2016). Hard and Soft Bottom Seafloor Substrate Map Derived from an Unsupervised Classification of Gridded Bathymetry Derivatives for the NOAA Habitat Blueprint West Hawaii Focus Area. https://www.fisheries.noaa.gov/inport/item/12618 [access date]

None

None

ArcGIS desktop and tools including Benthic Terrain Modeler (BTM), and from the ArcGIS Spatial Analyst extension the Principle Components Analysis (PCA) and the Iso Cluster Unsupervised Classification tools.

Hard- and soft-bottom substrate classifications are primarily derived from gridded bathymetry data that is collected from a number of NOAA vessels using multibeam sonars. This multibeam data may be synthesized with other data including bathymetric LiDAR . Multibeam data collection targets waters ranging from ~20 m to 500 m depths. Bathymetric LiDAR target waters less than 20-m depths. The goal of all data collection is to collect data over the entire seafloor within 0-500 m depths.

Horizontal positioning system: GPS C/A

Horizontal position accuracy: 25 m

Range resolution of sonar: varies with depth

Raw sounding resolution: varies with depth

Vertical accuracy of gridded product ~ 1% of water depth

Hard- and soft-bottom substrates were determined for all areas where gridded bathymetry data were available. Some gaps exist in bathymetry coverage due to 1) hazardous conditions that prohibited access for the NOAA vessels, 2) limited time, or 3) limited funding resources.

Multibeam bathymetry data were collected by different NOAA vessels using the same collection methods. All multibeam data collected by the Coral Reef Ecosystem Program (CREP) was processed in the same manner. All bathymetry synthesis data used as source data for the products generated for the Main Hawaiian Islands were processed in the same manner by the Hawaii Mapping Research Group. Seafloor imagery was collected by a number of different external partners using different methods; however, all imagery included in this project for the purposes of ground truthing was classified by CREP using the same classification scheme by experienced image analysts that are tested and calibrated annually.

Corrections for tide variation and vessel attitude are applied to the multibeam data and a CTD (Conductivity, Temperature, and Depth instrument) cast is performed regularly during data collection to correct for variance within the water column.

Multibeam data are tested for internal consistency; however, no effort is made to compare these data to external references or to other published data.

Hard/soft results from unsupervised classification were validated and corrected using optical ground truth imagery.

University of Hawaii School of Ocean and Earth Science and Technology, NOAA IRC and NOAA Fisheries ITS resources and assets.

The Iso Cluster Unsupervised Classification tool in ArcGIS was used to classify the three-band Principle Component Analysis image into two distinct hard vs soft substrate classes. Ground truth optical imagery as well as existing shallow water habitat maps provided by the USGS and NOAA Biogeography Branch were used to validate and correct the hard soft classification.