Habitat--Offshore of Ventura, California

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What does this data set describe?

Title: Habitat--Offshore of Ventura, California
Abstract:
This part of SIM 3254 presents data for the habitat map of the seafloor (see sheet 7, SIM 3254) of the Offshore of Ventura map area, California. The vector data file is included in "Habitat_OffshoreVentura.zip," which is accessible from <https://pubs.usgs.gov/ds/781/OffshoreVentura/data_catalog_OffshoreVentura.html>. Using multibeam echosounder (MBES) bathymetry and backscatter data, potential marine benthic habitat maps were constructed. The habitats were based on substrate types and documented or "ground truthed" using underwater video images and seafloor samples obtained by the USGS. These maps display various habitat types that range from flat, soft, unconsolidated sediment-covered seafloor to hard, deformed (folded), or highly rugose and differentially eroded bedrock exposures. Rugged, high-relief, rocky outcrops that have been eroded to form ledges and small caves are ideal habitat for rockfish (Sebastes spp.) and other bottom fish such as lingcod (Ophiodon elongatus). Habitat map is presented in a map format generated in a GIS (ArcMap), and both digital and hard-copy versions will be produced.
Supplemental_Information:
Data used for the creation of the potential marine benthic habitat interpretation consists of multibeam bathymetry, acoustic backscatter, sediment samples, camera-sled imagery, and existing geologic and seafloor interpretive maps. All data were compiled and displayed for interpretation using ESRI ArcGIS software, ArcMap v.9.3. The process consists of editing a shapefile within ArcMap, beginning with the construction of polygons to delineate benthic features. A benthic feature is an area with common characteristics which can be characterized as a single potential habitat type. The boundaries and extents of these features were determined from the bathymetric data. In general, interpretations were made at scales between 1:2,000 and 1:5,000. The USGS kindly provided the Center for Habitat Studies with a geodatabase consisting of feature datasets delineating geologic features and attributes for the Santa Barbara Channel. Some of the delineated polygons were preserved as part of the potential marine benthic habitat characterization. However, the Greene and others (2007) code was used in attributing the dataset and additional polygons were added using the methods outlined below. High-resolution multibeam sonar data in the form of bathymetric depth grids (seafloor digital elevation models, referred to as the "bathymetry") were the primary data used in the interpretation of potential habitat types. Shaded-relief imagery ("hillshade") allows for visualization of the terrain and interpretation of submarine landforms. On the basis of these hillshades, areas of rock were identified by their often sharply defined edges and high relative relief; these may be contiguous outcrops, isolated parts of outcrop protruding through sediment cover (pinnacles), or isolated boulders. Although these types of features can be confidently characterized as exposed rock, it is not uncommon to find areas within or around the rocky feature that appear to be covered by a thin veneer of sediment. These areas are identified as "mixed" induration, containing both rock and sediment. Broad areas of the seafloor lacking sharp and angular characteristics are considered to be sediment. Sedimentary features may contain erosional or depositional characteristics recognizable in the bathymetry, such as dynamic bedforms (dunes or sand waves). General morphologic features such as scours, mounds, and depressions were also identified using the hillshade imagery. The combination of acoustic backscatter data and "ground truthed" sediment samples were used to delineate seafloor sediment types within areas identified as "soft (s)" induration. Initially, ground truth data, in the form of grab sample descriptions and average grain size measurements, were categorized into four grain-size categories: mud (m), muddy sand (s/m), sand (s), and sandy gravel (s/g). Backscatter data was then classified into four intensity categories (low, med, high, very high) that are assumed to correspond to relative grain sizes. The aim was to develop an intensity classification of the seafloor that correlated with the data collected from the sediment samples. Thus, the combination of remotely observed data (acoustic backscatter) and directly observed data (sediment grab samples) translates to higher confidence in our ability to interpret broad areas of the seafloor. Nonetheless, we caution against using our sediment type interpretations as anything more than "best-guess" because of the following issues: characterization of contiguous sediment bodies is a difficult procedure because even small areas can exhibit a wide spectrum of backscatter-intensity values that lack distinct boundaries; backscatter intensity can be affected by depth, vegetation, water column conditions, and seafloor relief; and directly observed sediment data, in the form of sediment samples, represents a very small area relative to remotely observed data, requiring broad areas of interpolation. Please refer to Greene and others (2007) for more information regarding the Benthic Marine Potential Habitat Classification Scheme and the codes used to represent various seafloor features.
References Cited:
Greene, H.G., Bizzarro, J.J., O'Connell, V.M., and Brylinsky, C.K., 2007, Construction of digital potential marine benthic habitat maps using a coded classification scheme and its application, in Todd, B.J., and Greene, H.G., eds., Mapping the seafloor for habitat characterization: Geological Association of Canada Special Paper 47, p. 141-155.
Greene, H.G., Yoklavich, M.M., Starr, R.M., O'Connell, V.M., Wakefield, W.W., Sullivan, D.E., McRea, J.E., Jr., and Cailliet, G.M., 1999, A classification scheme for deep seafloor habitats: Oceanologica Acta, v. 22, no. 6, p. 663-678.
  1. How should this data set be cited?

    Endris, C.A., Greene, H.G., and Center for Habitat Studies, Moss Landing Marine Laboratories, 2013, Habitat--Offshore of Ventura, California:.

    This is part of the following larger work.

    Johnson, Samuel Y. , Dartnell, Peter, Cochrane, Guy R. , Golden, Nadine E. , Phillips, Eleyne L. , Ritchie, Andrew C. , Kvitek, Rikk G. , Greene, H. Gary , Krigsman, Lisa M. , Endris, Charles A. , Seitz, Gordon G. , Gutierrez, Carlos I. , Sliter, Ray W. , Erdey, Mercedes D. , Wong, Florence L. , Yoklavich, Mary M. , Draut, Amy E. , Hart, Patrick E. , and Cochran, Susan A. , 2013, California State Waters Map Series--Offshore of Ventura, California: Scientific Investigations Map SIM 3254, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -119.447481
    East_Bounding_Coordinate: -119.263216
    North_Bounding_Coordinate: 34.359236
    South_Bounding_Coordinate: 34.214948

  3. What does it look like?

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

    Calendar_Date: 2013
    Currentness_Reference: Publication Date

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

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

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

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • GT-polygon composed of chains (409)

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

      The map projection used is WGS 1984 UTM Zone 11N.

      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -117.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000000002220024164500956
      Ordinates (y-coordinates) are specified to the nearest 0.000000002220024164500956
      Planar coordinates are specified in Meter

      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.

  7. How does the data set describe geographic features?

    Habitat_OffshoreVentura
    Polygons representing habitat map units (Source: This report)

    OBJECTID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    Hab_Code
    Habitat code (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 20

    Hab_Type
    Habitat type (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 50

    Mega_ID
    Megahabitat ID code (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 10

    Mega
    Megahabitat description (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 35

    Ind_ID
    Seafloor induration ID code (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 15

    Ind
    Seafloor induration description (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 35

    Sed_ID
    Sediment ID code (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 15

    Sed
    Sediment description (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 35

    Mes_Mac_ID
    Meso/Macro-habitat ID code (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 35

    Mes_Mac
    Meso/Macro-habitat description (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 50

    Mod_ID
    Habitat modifier ID code (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 35

    Mod
    Habitat modifier description (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 50

    Slope_ID
    Slope modifier ID code (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 5

    Slope
    Slope description (Source: Center for Habitat Studies, Greene and others (1999, 2007))

    Names are in text form, maximum length: 35

    Area_m
    Polygon area in meters (Source: ESRI Calculate Geometry (Area in square meters) tool)

    Range of values
    Minimum:97.239197
    Maximum:4185460
    Units:Float values in square meters

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?

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

    Center for Habitat Studies, Moss Landing Marine Laboratories
    c/o H. Gary Greene
    Geologist/Principal Investigator
    Center for Habitat Studies
    Moss Landing Marine Labs, CA 95039
    USA

    (831) 771-4141 (voice)
    (831) 633-7264 (FAX)
    greene@mlml.calstate.edu

Why was the data set created?

This work is one of nine potential marine benthic habitat maps characterized after Greene and others (1999, 2007). These maps will be interpreted from MBES data collected by the CSMP in the Santa Barbara Channel area and elsewhere along the coast of central California.

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: 2011 (process 1 of 1)
    Interpretation and polygon delineation of habitats performed at scales from 1:2000 to 1:5000.

  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?

  2. How accurate are the geographic locations?

    Interpretation and polygon delineation of habitats performed at scales from 1:2000 to 1:5000

  3. How accurate are the heights or depths?

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

    Contact authors for information about omissions, selection criteria, generalization, definitions used, and other rules used to derive the data set.

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

    Map elements were visually checked for overshoots, undershoots, duplicate features, polygon closure, and other errors by the lead authors and by the GIS technician(s) who created the digital database. Review drafts of the map were reviewed internally by at least two other geologists for consistency with basic geologic principles and general conformity to USGS mapping standards.

How can someone get a copy of the data set?

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

Access_Constraints:
If physical samples or materials are available, constraints on their on-site access are described in "WR CMG Sample Distribution Policy" at URL: <http://walrus.wr.usgs.gov/infobank/programs/html/main/sample-dist-policy.html>
Use_Constraints:
This information is not intended for navigational purposes.
Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data.
Acknowledge the Center for Habitat Studies, Moss Landing Marine Laboratories in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.
This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.

Who wrote the metadata?

Dates:
Last modified: 10-Jul-2012
Metadata author:
Center for Habitat Studies, Moss Landing Marine Laboratories
c/o Charlie Endris
Geologist/GIS Analyst
8272 Moss Landing Rd.
Moss Landing, CA 95039
US

831-771-4141 (voice)
831-633-7264 (FAX)
cendris@mlml.calstate.edu

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.9.6 on Tue Jul 09 17:28:44 2013