CRED Towed-Diver Benthic Characterization Surveys at Saipan Island, Marianas Archipelago in 2003

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What does this data set describe?

Title:
CRED Towed-Diver Benthic Characterization Surveys at Saipan Island, Marianas Archipelago in 2003
Abstract:
To support NOAA Coral Reef Conservation Program (CRCP) long-term goals for sustainable management and conservation of coral reef ecosystems, towed-diver surveys (aka. towboard surveys) were conducted by the Coral Reef Ecosystem Division (CRED) of the NOAA Pacific Islands Fisheries Science Center (PIFSC) as part of biennial Pacific Reef Assessment and Monitoring Program (RAMP) Cruises. 6 towboard surveys (11.8192 km in length), were conducted at Saipan Island during the Marianas Archipelago RAMP Cruise OES0307 from 19 August - 30 September 2003. Towboard surveys are a good method for obtaining a general description of large reef areas, assessing the status of low-density populations of large-bodied reef fish, large-scale disturbances (e.g., bleaching), general distribution and abundance patterns of macro-invertebrates (e.g., COT, giant clams), and for assessing trends in these populations and metrics. A pair of scuba divers (1 fish and 1 benthic diver) are towed 60 m behind a small survey launch at a speed of 1-2 knots and a depth of approximately 15m. Each survey is 50 min long, covers about 2 km of habitat, and is divided into ten 5-minute survey segments. The fish diver records, to the lowest possible taxon, all large-bodied reef fishes (>50cmTL) seen within 5m either side and 10m in front of the towboard. Length of each individual is estimated to the nearest cm. The fish towboard is also outfitted with a forward-facing digital video camera to record the survey swath. The benthic diver records percent cover of coral and macroalgae, estimates benthic habitat type and complexity, and censuses a suite of benthic macroinvertebrates including Crown of Thorns sea stars and sea urchins. The benthic towboard is equipped with a downward-facing digital still camera which images the benthos at 15 second intervals. These images are analyzed for percent cover of coral, algae, and other benthic components. Both towboards are equipped with SEABIRD SBE-39 temperature/depth sensors set to record at 5 second intervals. Latitude and longitude of each survey track is recorded at 15 second intervals using a Global Positioning System (GPS) receiver onboard the tow boat. A layback algorithm is applied to more accurately map the position of the divers with respect to the reef environment. This algorithm calculates the position of the divers based on the position of the tow boat taking into account the length of the tow rope, the depth of the divers, and the curvature of the survey track. This metadata applies to the benthic characterization observations.
Supplemental_Information:
The benthic characterization observation data includes benthic composition, complexity estimations, observed macro-invertebrates, and observed man-made objects. Classification of habitat complexity was recorded in six categories: low (L), medium-low (ML), medium (M), medium-high (MH), high (H), and very high (VH). Benthic cover was estimated for four different types of substrate: hard substrate/pavement, sand, rubble, and live hard (scleractinian) coral. The time of the benthic digital photos were set to the GMT time. There were approximately 200 pictures of each 50-minute towed survey track. The resolution at "Draft" quality (the lowest) is 72 pixels/inch. The resolution at "Best" quality (the highest) is 266 pixels/inch. The naming convention of benthic photos is ***MMDDYY_X_###.JPG, where *** is 3 letters abbreviation of island/bank surveyed, MMDDYY is the local date of towboard survey, X is the Xth dive on the day of MMDDYY, and ### is the sequence number of the pictures taken at the Xth dive. For example, JAR032106_3_108.JPG means the picture was the 108th picture taken at 3rd dive on March 21, 2006 at Jarvis Island.
  1. How should this data set be cited?

    Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), 20050822, CRED Towed-Diver Benthic Characterization Surveys at Saipan Island, Marianas Archipelago in 2003.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: 145.682035
    East_Bounding_Coordinate: 145.848199
    North_Bounding_Coordinate: 15.298604
    South_Bounding_Coordinate: 15.079644

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 22-Aug-2003
    Ending_Date: 22-Aug-2003
    Currentness_Reference: Ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: spreadsheet

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Decimal Degrees.

      The horizontal datum used is World Geodetic System 1984 (WGS84).
      The ellipsoid used is Geodetic Reference System 80 (GRS80).
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.2572236.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit Depth Coordinate Included with Horizontal Coordinates

  7. How does the data set describe geographic features?


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Rusty Brainard and Molly Timmers, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Sciences Center, National Marine Fisheries Service, NOAA

  3. To whom should users address questions about the data?

    Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    NOAA IRC
    Honolulu, HI 96818
    USA

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred


Why was the data set created?

Part of a long-term monitoring program at biennial intervals which documents the state of the reefs.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: Unknown (process 1 of 1)
    Benthic towed-diver surveys involve a SCUBA diver who maintains approximately 1 meter above the bottom and is towed 60 m behind a boat at a constant speed (~1.5 knots). The diver maneuvers a towboard equipped with a downward facing still camera that is programmed to take photographs of the benthos at every 15 seconds as well as a SBE39 depth/temperature recorder which records the temperature and depth every 5 seconds. The towboard survey is typically 50 min long and covers about 2 km of habitat, depending on the depth profile of the divers. The survey is divided into 5 min segments. During the survey, the benthic diver records benthic composition, complexity estimations, observed macro-invertebrates, and observed man-made objects.

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Observations were made by the divers who are experts in coral reef ecologist. Surveying in this habitat will greatly depend on the current, wave conditions and field scheduling. The towed-diver survey is conducted one time per site per survey year; it is not replicated. Divers may change from year to year and by location.

  2. How accurate are the geographic locations?

    Although resource grade GPS units were used and a layback model was applied to the survey tracks, the exact survey positions were rarely marked and little effort was made to revisit exact same tracks.

  3. How accurate are the heights or depths?

    Dive computer and SCUBA depth gauge

  4. Where are the gaps in the data? What is missing?

    The towed-diver surveys are completed in forereef, backreef, and lagoon habitats. Considering that the towed-divers are covering ~200 m during each 5-min time frame of a 50-minute survey, benthic coverage calculations are broad estimates. These data can be used to see large differences but can not be process to a fine scale.

  5. How consistent are the relationships among the observations, including topology?

    The same data collection protocols were used at each island/bank surveyed.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: Data are available two years following data collection date.
Use_Constraints:
Please cite CRED when using the data. Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration

  1. Who distributes the data set? (Distributor 1 of 1)

    Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    Attn: CRED data management team
    NOAA IRC
    Honolulu, HI 96818
    USA

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred
  2. What's the catalog number I need to order this data set?

    Offline Data

  3. What legal disclaimers am I supposed to read?

    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.

  4. How can I download or order the data?

  5. Is there some other way to get the data?

    Contact CRED data management team for information

  6. What hardware or software do I need in order to use the data set?

    Contact CRED data management team for information


Who wrote the metadata?

Dates:
Last modified: 29-Sep-2014
Last Reviewed: 07-Apr-2010
Metadata author:
Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
NOAA IRC
Honolulu, HI 96818
USA

808 725-5360 (voice)
808 725-5429 (FAX)
nmfs.pic.credinfo@noaa.gov

Contact_Instructions: e-mail preferred
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


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