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Benthic cover derived from structure from motion images collected during marine debris surveys at coral reef sites entangled with derelict fishing nets at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands from 2018-09-24 to 2018-10-03 (NCEI Accession 0209247)

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The benthic cover and fishing-net related data described in this dataset are derived from the GIS analysis of benthic orthophotos. The source imagery was collected using a Structure from Motion (SfM) approach during in-water marine debris swim surveys conducted by snorkelers in search of derelict fishing nets. Surveys were conducted by the NOAA Fisheries, Ecosystem Sciences Division (ESD) from September 24 to October 3, 2018 at Pearl and Hermes Atoll during an ESD-led marine debris mission to the Northwestern Hawaiian Islands (NWHI) aboard NOAA Ship Oscar Elton Sette. The lagoon at Pearl and Hermes was surveyed equally across the spatial gradient, from locations where derelict fishing nets are common to locations where derelict fishing nets have never been observed.

During the 2018 mission, only a subset of marine debris surveys resulted in a SfM survey. Fishing nets were located during swim surveys and selected for SfM if the net was interacting with coral or hard substrate, the depth of the net was within ~1–4 m of the surface, and the area of the net fit within the 9 sq. meter SFM survey plot. During a SFM survey, a permanent 3 x 3 m plot was established around the center of the fishing net, and the net was photographed using a back and forth swim pattern (“before” photos) for later processing using a SfM approach. The net was then removed, the volume of net removed was estimated and recorded, and the same area was photographed again in the same way (“after” photos). A nearby (>50 m distant) paired control site was also photographed using the same method (“control” photos).

The photographs were processed using Agisoft Metashape software to generate orthomosaic images that were analyzed in ArcGIS for benthic cover using a random point approach. The number of points at net-impacted sites were constrained to the net coverage area and were scaled to the net area to ensure an equal point density among replicate net-impact sites. The same number of points were randomly assigned to the 3 × 3 m paired control site. Each point was classified into one of seven benthic categories: turf algae, macroalgae, sand, bare substrate, Porites compressa, sponge, or crustose coralline algae (CCA). The annotated points for each site were converted to percent cover for each benthic category. Fishing net size (sq m) and degree of fouling were also calculated from the orthophotos. Analyses were conducted to compare the benthic composition of net sites to control sites and to determine if fouling or net size contributed to these differences.
  • Cite as: Ecosystem Sciences Division, Pacific Islands Fisheries Science Center (2020). Benthic cover derived from structure from motion images collected during marine debris surveys at coral reef sites entangled with derelict fishing nets at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands from 2018-09-24 to 2018-10-03 (NCEI Accession 0209247). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0209247. Accessed [date].
gov.noaa.nodc:0209247
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Distributor NOAA National Centers for Environmental Information
+1-301-713-3277
NCEI.Info@noaa.gov
Dataset Point of Contact NOAA National Centers for Environmental Information
ncei.info@noaa.gov
Time Period 2018-09-24 to 2018-10-03
Spatial Bounding Box Coordinates
West: -175.8211335
East: -175.7880926
South: 27.82745706
North: 27.89404863
Spatial Coverage Map
General Documentation
Associated Resources
  • Benthic cover and other related datasets derived from Structure-from-Motion (SfM) imagery of coral reef ecosystems in Pacific Islands Regions
    • NCEI Collection
      Navigate directly to the URL for data access and direct download.
  • NOAA Pacific Islands Fisheries Science Center, Ecosystem Sciences Division (2022). Benthic cover derived from structure from motion images collected during marine debris surveys at coral reef sites entangled with derelict fishing nets at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands from 2021-09-13 to 2021-09-14 (NCEI Accession 0253462). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0253462.
  • Pacific Islands Fisheries Science Center, 2022: Benthic cover derived from structure from motion images collected during marine debris surveys at coral reef sites entangled with derelict fishing nets at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands from missions in 2018 and 2021, https://www.fisheries.noaa.gov/inport/item/59172.
  • Successful application of a novel technique to quantify negative impacts of derelict fishing nets on Northwestern Hawaiian Island reefs
  • Integrating structure-from-motion photogrammetry with geospatial software as a novel technique for quantifying 3D ecological characteristics of coral reefs
  • Derelict fishing gear in the Northwestern Hawaiian Islands: diving surveys and debris removal in 1999 confirm threat to coral reef ecosystems
  • Processing Photomosaic Imagery of Coral Reefs Using Structure-from-Motion Standard Operating Procedures
  • 2018 Marine Debris Removal and Assessment in the Northwestern Hawaiian Islands
  • Parent ID (indicates this dataset is related to other data):
    • gov.noaa.nodc:PIFSC-SfM-DerivedData
Publication Dates
  • publication: 2020-05-13
Data Presentation Form Digital table - digital representation of facts or figures systematically displayed, especially in columns
Dataset Progress Status Complete - production of the data has been completed
Historical archive - data has been stored in an offline storage facility
Data Update Frequency As needed
Supplemental Information
Submission Package ID: 6RT3B5
Purpose The purpose of the Structure from Motion (SfM) surveys at Pearl and Hermes Atoll is to quantify how derelict fishing nets alter the benthic community composition of the reef. In addition, we investigated how net size and fouling level may vary the severity of this impact. This study leveraged SfM, an emerging photogrammetry technique, to allow efficient data collection alongside marine debris survey and removal efforts. The Papahānaumokuākea Marine National Monument (PMNM) includes the 1200 nautical mile chain of atolls and islets known as the Northwestern Hawaiian Islands (NWHI) that are geographically positioned as a repository for marine debris. Marine debris circulates within the North Pacific Subtropical Gyre until it encounters the atolls of the NWHI. The Ecosystem Sciences Division (ESD) at NOAA Fisheries has conducted both ship- and shore-based missions in the NWHI to survey for and remove derelict fishing gear and many other types of marine debris. Exploratory and opportunistic efforts began in 1996 that evolved into ~annual cruises.
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  • accessLevel: Public
  • Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
Dataset Citation
  • Cite as: Ecosystem Sciences Division, Pacific Islands Fisheries Science Center (2020). Benthic cover derived from structure from motion images collected during marine debris surveys at coral reef sites entangled with derelict fishing nets at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands from 2018-09-24 to 2018-10-03 (NCEI Accession 0209247). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0209247. Accessed [date].
Cited Authors
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Theme keywords NODC DATA TYPES THESAURUS NODC OBSERVATION TYPES THESAURUS WMO_CategoryCode
  • oceanography
CoRIS Discovery Thesaurus
  • Numeric Data Sets > Benthic
CoRIS Theme Thesaurus
  • EARTH SCIENCE > Biosphere > Aquatic Habitat > Benthic Habitat
  • EARTH SCIENCE > Biosphere > Aquatic Habitat > Reef Habitat
  • EARTH SCIENCE > Biosphere > Vegetation > Algae
  • EARTH SCIENCE > Biosphere > Vegetation > Algae > Algal Cover
  • EARTH SCIENCE > Biosphere > Vegetation > Algae > Coralline Algae
  • EARTH SCIENCE > Biosphere > Vegetation > Algae > Crustose Coralline Algae
  • EARTH SCIENCE > Biosphere > Vegetation > Algae > Fleshy Macroalgae
  • EARTH SCIENCE > Biosphere > Vegetation > Algae > Turf Algae
  • EARTH SCIENCE > Biosphere > Zoology > Corals
  • EARTH SCIENCE > Biosphere > Zoology > Corals > Reef Damage Assessment > Marine Debris
  • EARTH SCIENCE > Biosphere > Zoology > Corals > Reef Monitoring and Assessment
  • EARTH SCIENCE > Biosphere > Zoology > Corals > Reef Monitoring and Assessment > Benthos Analysis
  • EARTH SCIENCE > Biosphere > Zoology > Corals > Reef Monitoring and Assessment > In Situ Biological
  • EARTH SCIENCE > Biosphere > Zoology > Corals > Reef Monitoring and Assessment > Photographic Analysis
  • EARTH SCIENCE > Biosphere > Zoology > Sponges
  • EARTH SCIENCE > Oceans > Coastal Processes > Coral Reefs
  • EARTH SCIENCE > Oceans > Coastal Processes > Coral Reefs > Coral Reef Ecology > Benthic biology
  • EARTH SCIENCE > Oceans > Coastal Processes > Coral Reefs > Coral Reef Ecology > Coral Cover
  • EARTH SCIENCE > Oceans > Coastal Processes > Coral Reefs > Coral Reef Ecology > Hard Coral Cover
  • EARTH SCIENCE > Oceans > Marine Biology > Coral
  • EARTH SCIENCE > Oceans > Marine Biology > Marine Invertebrates
Global Change Master Directory (GCMD) Science Keywords
Data Center keywords NODC COLLECTING INSTITUTION NAMES THESAURUS NODC SUBMITTING INSTITUTION NAMES THESAURUS Global Change Master Directory (GCMD) Data Center Keywords
Platform keywords NODC PLATFORM NAMES THESAURUS Global Change Master Directory (GCMD) Platform Keywords ICES/SeaDataNet Ship Codes
Instrument keywords NODC INSTRUMENT TYPES THESAURUS
Place keywords NODC SEA AREA NAMES THESAURUS CoRIS Place Thesaurus
  • COUNTRY/TERRITORY > United States of America > Hawaii > Honolulu > Northwestern Hawaiian Islands (28N178W0000)
  • COUNTRY/TERRITORY > United States of America > Hawaii > Honolulu > Pearl and Hermes Reef (27N176W0001)
  • OCEAN BASIN > Pacific Ocean > Central Pacific Ocean > Northwestern Hawaiian Islands (28N178W0000)
  • OCEAN BASIN > Pacific Ocean > Central Pacific Ocean > Northwestern Hawaiian Islands > Pearl and Hermes Reef (27N176W0001)
Global Change Master Directory (GCMD) Location Keywords
Project keywords NODC PROJECT NAMES THESAURUS
Keywords NCEI ACCESSION NUMBER
Use Constraints
  • Cite as: Ecosystem Sciences Division, Pacific Islands Fisheries Science Center (2020). Benthic cover derived from structure from motion images collected during marine debris surveys at coral reef sites entangled with derelict fishing nets at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands from 2018-09-24 to 2018-10-03 (NCEI Accession 0209247). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0209247. Accessed [date].
Access Constraints
  • Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
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  • In most cases, electronic downloads of the data are free. However, fees may apply for custom orders, data certifications, copies of analog materials, and data distribution on physical media.
Lineage information for: dataset
Processing Steps
  • 2020-05-13T19:12:09Z - NCEI Accession 0209247 v1.1 was published.
Output Datasets
Lineage information for: dataset
Processing Steps
  • Parameter or Variable: DEBRIS (calculated); Units: square meters (m^2); Observation Category: derived products; Sampling Instrument: photograph; Sampling and Analyzing Method: Using the "before" orthomosaic, the planar fishing net area on the substrate (square meters) was calculated by delineating the net boundary with a polygon shapefile and using the Calculate Geometry tool in ArcMap v10.6.1.; Data Quality Method: Field Precision: The size of nets removed from net-impact sites ranged from 0.48 m2 to 4.46 m2 (mean area = 2.0 m2). Completeness Report: Each image set was evaluated for image quality. Images deemed unsatisfactory, e.g., blurred or had unnecessary objects (e.g., dive fins), were removed from the image set. Conceptual Consistency: The same method of image collection and analysis was used at each surveyed site..
  • Parameter or Variable: REEF AND/OR BOTTOM REGIME - PERCENT COVER (calculated); Units: percent; Observation Category: derived products; Sampling Instrument: photograph; Sampling and Analyzing Method: Using the "after" orthomosaic, benthic cover was assessed using a random point approach within the boundary of the net (based on the net boundary shapefile) in ArcMAP 10.6.1.The number of points at net-impacted sites was scaled to the planar net area to ensure an equal point density (mean point density = 10.9 points/m2 ± 0.40 SE) among replicate net-impact sites. Using the paired "control" orthomosaic, the same number of points were randomly assigned to the 3 x 3 m control site. Each point was classified into one of seven benthic categories: turf algae, macroalgae, sand, bare substrate, Porites compressa, sponge, and crustose coralline algae (CCA). The annotated points for each site were converted to percent cover (number of points for a given category/total number of points x 100) for each benthic category. Analyses were conducted to compare the benthic composition of net sites to control sites.; Data Quality Method: Representativeness: The data set derived from the image analysis is as good as the mosaic image itself; points that fell within areas of low contrast, shadow, obstruction, or blur were discarded and new random points were generated so that each point could be analyzed for percent cover. Accuracy: Prior to conducting surveys, researchers are trained to identify benthic taxa. Both classroom and field training were completed for all researchers (experienced and inexperienced alike) before any surveys were conducted. This training ensures that all analysis is conducted consistently by all analysts. Field Precision: The Ground Sample Distance (GSD, resolution/pixel) for the produced 3D Structure from Motion models ranged from 0.000122 to 0.000618 m/pix with an error of 1.11 to 3.03 pix, allowing confident identification of benthic species from the resulting high-resolution 2D photomosaics. Completeness Report: Images that were blurred or had unnecessary objects (e.g., dive fins) were removed. Conceptual Consistency: The same method of image collection and analysis was used at each surveyed site. Quality Control Procedures Employed: The benthic category assigned to each random point across each mosaic were verified by an expert. Any points that fell onto an unidentifiable area (i.e., shadow) were re-generated..
  • Parameter or Variable: DEBRIS (calculated); Units: kilogram; Observation Category: in situ; Sampling Instrument: scale; Sampling and Analyzing Method: The volume of each fishing net removed from the reef was estimated when brought aboard the small boat. At the end of the marine debris survey, which could include one to several structure-from-motion surveys, or when the small boat reached its capacity, the small boat returned to the ship and the boat’s entire debris load was weighed and recorded. The estimated volume of each net was used to determine the percentage each net contributed to the boat's entire load, and weights for each net were calculated based on the percentage.; Data Quality Method: The weight of each individual net is estimated from the weight for the entire boat load..
  • Parameter or Variable: DEBRIS (calculated); Units: unitless; Observation Category: derived products; Sampling Instrument: photograph; Sampling and Analyzing Method: Using the "before" orthomosaic, degree of fouling was estimated for each fishing net based on the percent of the net surface area that was covered by fouling organisms. Fouling scores ranged from 1 to 3, where: 1 = Light: 1-40% of net surface area covered, 2 = Moderate: 41-75% of net surface area covered, and 3 = Heavy: >75% of net surface area covered (adapted from Donohue et al., 2001).; Data Quality Method: Four nets were classified as fouling level 1, eight nets as fouling level 2, and eight nets as fouling level 3..
Acquisition Information (collection)
Instrument
  • photograph
  • scale
  • swimmer/diver
Platform
  • NOAA Ship Oscar Elton Sette
Last Modified: 2023-02-06T13:43:14Z
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