Nearshore Benthic Habitats of Timor-Leste Derived from WorldView-2 Satellite Imagery

Benthic habitat classes were derived for nearshore waters (< 20 m depths) around Timor-Leste from DigitalGlobe WorldView-2 satellite imagery, acquired from February 9, 2010 to December 14, 2013, by the NOAA Coral Reef Ecosystem Program (CREP). Habitat classes include soft (sand or mud) and hard (rubble, boulders, etc.) substrates by depth (shallow, mid and deep); seagrass, mangrove, and macroalgae dominated areas; intertidal zones; lagoons; and emergent rocks. Supervised classifications were performed using several different methods (maximum likelihood, and minimum distance) with imagery at several different stages of processing (deglinted, radiance, reflectance and deglinted, depth invariant, sieve, and clump), with final classification based on the classification method and imagery variant that provided the best overall results for each WorldView-2 image.

In 2011, NOAA and the United States Agency for International Development (USAID) Timor-Leste Mission formed a 5-year bi-lateral partnership agreement from 2012 to 2016, in support of the Government of Timor-Leste—particularly the Ministry of Agriculture and Fisheries (MAF)—by addressing significant information gaps in their nearshore marine ecosystems. Specifically, MAF asked NOAA to address the following questions:

1. Where are the nearshore marine resources?

2. What are the nearshore marine resources?

3. How are they changing over time and what threats are potentially causing these changes?

4. What approaches are needed to manage and conserve the nearshore marine resources?

With financial support from USAID and in-kind support from the NOAA Coral Reef Conservation Program (CRCP), the NOAA Coral Reef Ecosystem Program (NOAA-CREP) conducted baseline ecosystem assessment surveys to inform ecosystem-based management planning in Timor-Leste. The primary activities conducted by NOAA to answer these questions included:

1. satellite mapping of nearshore habitats,

2. conducting coral reef ecosystem assessments,

3. establishing ecological baselines for climate change, and

4. building management capacity by developing a spatial data framework

The benthic habitat classification data described herein resulted from the first activity to conduct satellite mapping for the nearshore waters around Timor-Leste.

Pacific Islands Fisheries Science Center. 2017. Interdisciplinary baseline ecosystem assessment surveys to inform ecosystem-based management planning in Timor-Leste: Final Report. Pacific Islands Fisheries Science Center, PIFSC Special Publication, SP-17-002, 234 p. https://doi.org/10.7289/V5/SP-PIFSC-17-002.

Benthic habitat raster files, in geotiff format, derived from WorldView-2 satellite imagery from coastal waters of Timor-Leste. Values 1-15 correspond to the following 15 habitat classes, in sequential (VALUE) order: hard shallow, soft shallow, hard mid, soft mid, hard deep, soft deep, seagrass, unknown, mangrove, intertidal, emergent rocks, macroalgae, lagoon, hard, and soft. These classes are grouped into the following types: hard substrate, soft substrate, seagrass, unknown, mangrove, intertidal, emergent rocks, macroalgae, and lagoon.

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.

Timor-Leste

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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 United States Agency for International Development (USAID). The analysis and interpretations presented here are solely that of the current authors.”

Data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive

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

Example

Coral Reef Ecosystem Program; Pacific Islands Fisheries Science Center (2017). Nearshore Benthic Habitats of Timor-Leste Derived from WorldView-2 Satellite Imagery. NOAA's National Center for Environmental Information. Dataset. https://www.fisheries.noaa.gov/inport/item/29128

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Maps were developed using standard image processing software, including ArcGIS version 10.3, ENVI version 4.8, and Microsoft Excel version 14.0.73162.5000.

Limited validation data are available, precluding a quantitative error analysis. Preliminary maps were reviewed by a few persons working in coral reef ecosystems in Timor-Leste and their comments and corrections were incorporated into the final maps.

Little-to-no ground truth data are available; therefore, no error analysis was conducted because there was no way to quantify correctness of the data.

Nearshore waters along the coast of Timor-Leste are completely covered with WorldView-2 satellite imagery. There are, however, holes in derived habitat layers resulting from areas of high water column turbidity, clouds, whitewater, etc. that were masked out of the analyses due to a lack of reliable imagery of the seafloor for those areas. Multiple overlapping images of some portions of the shoreline enabled sections of different images to be extracted and used to patch holes in other images in some cases, in a process known as "cloud patching." This process enabled more complete coverage to be developed. Imagery was acquired for Timor-Leste from Jan 26 2010 to Aug 10, 2014. The subset of imagery used to derive habitats was from February 9, 2010 to December 14, 2013.

Pre-processing of all WorldView-2 satellite images was performed using the same methods, to produce a deglinted image, radiance and depth invariant data layers. Three different supervised classification algorithms were run for each data layer, including Mahalanobis Distance, Maximum Likelihood and Minimum Distance methods. All three algorithms were run alone and also followed, when it appeared necessary, by Sieve and Sieve Clump post-classification steps to merge nearby pixels together. The resulting habitat maps were compared to select the method that produced the best results for each of the WorldView-2 images.

An experienced outside contractor was hired to review and suggest modifications to improve the the initial methods for deriving benthic habitat data from WorldView-2 satellite imagery.

Three different modifications for both types of processing were performed on each image. A visual comparison of the 6 resulting geotiffs was made to select the one that best reflected the distribution of benthic habitats for each WorldView-2 satellite image.

NOAA IRC and NOAA Fisheries ITS resources and assets.

Benthic habitat classes were derived for nearshore waters around Timor-Leste from WorldView-2 satellite imagery. Habitat classes include different combinations of shallow, mid and deep depths, soft (sand or mud) or hard (rubble, boulders, etc.) substrates, macroalgae, seagrass or mangrove dominated areas, intertidal areas, lagoons, and emergent rocks. Supervised classifications were performed using several different methods and with imagery at several different stages of processing, with final classification based on the classification method and imagery variant that provided the best overall results for each WorldView-2 image.