[ Bathymetry | Backscatter | Optical Validation | Benthic Habitat | 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
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| Descriptions of optical data products. |
| Download: Accessory Files |
The map above shows percent cover values of scleractinian coral derived from classified videos collected at the Auau Channel, Maui, Hawaii in 2007, 2008 and 2009. Video data were collected by CRED’s TOAD camera sled in 2008 aboard NOAA ship Oscar Elton Sette, cruise SE0807 and in 2009 aboard NOAA ship Hi’ialakai, cruise HA0905. Different from other optical validation maps, this map also includes analyzed video collected by several scientists and researches aboard the Hawaii Undersea Research Laboratory (HURL)’s R/V Ka`imikai-o-Kanaloa, using the Remotely Operated Vehicle (ROV) RCV-150. ROV data collection occurred in 2007, and two cruises in 2009. Each point symbolized with the red color ramp represents an analyzed video frame or photo. Note that the percent classes are unevenly sized to better display this relatively low-abundance bottom type. Points symbolized in yellow represent recently collected TOAD camera sled video data that have not yet been classified fully. This map will be updated with all tow tracks classified showing percent cover of scleractinian coral upon completion of video analyses.
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.
Predicted Coral Distribution
Scleractinian coral cover data was used in conjunction with environmental data to predict the distribution of scleractinian coral in mesophotic depths throughout the Au’au Channel, using a modeling technique called Maximum Entropy modeling. Freely available Maximum Entropy (MaxEnt) modeling software (MaxEnt 3.3.3e) was used to create four separate maps of predicted habitat suitability for:
- (1) all mesophotic hard corals combined,
- (2) Leptoseris,
- (3) Montipora, and
- (4) Porites.
MaxEnt works by analyzing the distribution of environmental variables where species are present, so it can find other areas that meet all of the same environmental constraints. Georeferenced records containing information about mesophotic coral occurrence and 34 environmental predictors describing the seafloor’s depth, vertical structure, available light, surface temperature, currents and distance from shoreline were used to train MaxEnt. A subset of the georeferenced coral records were set aside to assess model accuracy.
Models were developed for all hard corals combined, and then separately for Leptoseris, Montipora and Porites. These three corals were chosen, as they were the most common genera of mesophotic corals observed, and there were sufficient observations of these genera to create a model.
Results from this study can be used for a range of management applications including identifying likely areas for protection within marine protected areas, targeting areas for research activities, and evaluating potential conflict with human activities in the area.
These models do not replace accurately obtained direct observations (e.g., from towed camera, ROV or AUV surveys) but they do help to fill some gaps about the likely distribution of mesophotic coral ecosystems within the Au’au Channel.
This project, was carried out by Biogeography Branch, Center for Coastal Monitoring and Assessment (CCMA), NOAA National Centers for Coastal Ocean Science (NCCOS). The detailed report of methods and results can be downloaded from here:
http://ccma.nos.noaa.gov/ecosystems/sanctuaries/hwnms/
Predicted Distribution of Hard Coral Habitat
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The map above shows the predicted habitat suitability of hard coral in the Au’au Chanel, from MaxEnt model. Influential environmental variables in this model were mean euphotic depths, mean depth, and standard deviation of euphotic depth.
Predicted distribution of Leptoseris coral
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The map above shows the predicted habitat suitability of Leptoseris coral in the Au’au Chanel, from MaxEnt model. Influential environmental variables in this model were slope of slope (at 200-m analysis scale), mean and standard deviation of euphotic depth, and mean depth (at 25-m analysis scale).
Predicted distribution of Montipora coral
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The map above shows the predicted habitat suitability of Montipora in the Au’au Chanel, from MaxEnt model. Influential environmental variables in this model were mean euphotic depth, mean depth (at 10-m scale), and mean sea surface temperature.
Predicted distribution of Porites coral
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The map above shows the predicted habitat suitability of Porites in the Au’au Chanel, from MaxEnt model. Influential environmental variables in this model were mean depth calculated at 10-m and 25-m analysis scale.