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Eelgrass Sample Points

Frequently-asked questions:


What does this data set describe?

Title:
Eelgrass Sample Points

Abstract:
Eelgrass Sample Points is a 1:24,000-scale, point feature-based layer that depicts the locations where eelgrass (Zostera marina) was either observed or where a location would be potentially favorable for future eelgrass growth.  Sample points were taken along Connecticut's coast in Long Island Sound, and in major bays, harbors and rivers along the shoreline.  The point features in this layer were compiled from field research using global positioning system (GPS) equipment.  Feature locations were not always exact due to equipment failure or lack of satellite reception.  In those cases, points were estimated from field notes.  Some point locations were corrected based on field notes or hydrography and bathymetry conditions at the sample point location.  The number of field points that were altered were as follows:  In 1993, 32 of 290 points (11%); in 1994, 93 of 454 points (20%); in 1995, 37 of 105 points (35%).  Data compilation occurred on 17 days between 7/21/1993 and 11/16/1995; exact dates of each source's data collection are noted in the attribute table.  

A total of 849 point locations were surveyed.  The westernmost point is Frash Pond in Stratford, Connecticut and the easternmost point is the Pawcatuck River on the Connecticut/Rhode Island Border.  Eelgrass was found at 484 locations and was described as either high, medium, or low density, or simply as present or absent.  Eelgrass was absent at 365 locations. 

Publication of the datalayer was in 1997.  This layer is not updated.  This layer does not represent current conditions.

Supplemental information:
For more information on the eelgrass polygon layers created from this layer, refer to the metadata for Observed Eelgrass and Potential Eelgrass layers.  

  1. How should this data set be cited?

    Dr. Charles Yarish, University of Connecticut Dept. of Ecology and Evolutionary Biology (data compiler ), University of Connecticut, Long Island Sound Resource Center (editor), State of Connecticut, Department of Environmental Protection (publisher), 1997, Eelgrass Sample Points: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Other citation details:
    This layer is not updated and does not represent current conditions.

  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -73.132805
    East: -71.849071
    North: 41.462981
    South: 41.166632

  3. What does it look like?

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/eelgrassbedsamplepointsfullview.gif (GIF)
    Full view of Eelgrass Sample Points.

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/eelgrassbedsamplepointsdetailview.gif (GIF)
    Detail view of eelgrass sample points.

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

    Calendar date: 1997
    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?

      Indirect spatial reference:
      State of Connecticut, United States of America

      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Entity point (849)
      • Point (216)

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

      The map projection used is Lambert Conformal Conic.

      Projection parameters:
      Lambert Conformal Conic
      Standard parallel: 41.200000
      Standard parallel: 41.866667
      Longitude of central meridian: -72.750000
      Latitude of projection origin: 40.833333
      False easting: 999999.999996
      False northing: 499999.999998

      Planar coordinates are encoded using coordinate pair.
      Abscissae (x-coordinates) are specified to the nearest 0.000250.
      Ordinates (y-coordinates) are specified to the nearest 0.000250.
      Planar coordinates are specified in survey feet.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical coordinate system definition:
      Altitude system definition:
      Altitude resolution: 1.000000
      Altitude encoding method: Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    Eelgrass Sample Points
    Eelgrass Sample Points stored as digital vector data (Source: State of Connecticut, Department of Environmental Protection)

    OBJECTID
    Internal feature number. (Source: ESRI)
                      

    Sequential unique whole numbers that are automatically generated.

    SHAPE
    Feature geometry. (Source: ESRI)
                      

    Coordinates defining the features.

    DATECOLL
    Date that the data was collected. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Date in a MM/DD/YY format.

    LOCATION
    A general description of field location. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Text describing location.

    LATD
    Degrees latitude, as recorded from GPS. (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    41
    Latitude degrees of all points

    LATM
    Minutes latitude, as recorded from GPS. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Decimal number.

    LOND
    Degrees longitude, as recorded from GPS. (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    72
    Longitude degrees of all points.

    LONM
    Minutes longitude, as recorded from GPS. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Decimal number.

    DENSITY
    Describes density or presence of eelgrass bed. (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    A
    Absent
    P
    Present
    H
    High Density
    M
    Medium Density
    L
    Low Density

    DEPTHM
    Approximate depth in meters, as measured by divers, not corrected for tides. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Decimal number.

    TIMECOLL
    Approximate time as recorded in field based on a 12 hour clock. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Time of day in the format HH/MM.

    COMMENTS
    Field Comments.  May describe condition of eelgrass, more detailed location, bottom type, salinity, associated flora and fauna, in particular, ruppia maritima. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Text describing comments.

    SEAWEED
    Seaweed noted as absent or present or contains up to 5 abbreviated names of seaweeds for each feature.   (Source: State of Connecticut, Department of Environmental Protection)
                      

    Text description of seaweed, "present", or "absent"

    PLOT_LOC
    Plotted location point type.   (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    O
    Original point location.
    A
    Altered point location

    YR
    Two digit year (extracted from Date field). (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    93
    Year of data collection in YY format.
    94
    Year of data collection in YY format.
    95
    Year of data collection in YY format.

    Entity and attribute overview:
    Includes Eelgrass Sample point features such as data collection date, location of points, latitude and longitude degrees and minutes, density of eelgrass, depth, time of data recording, comments,  types of seaweed in area, plotted location, observed eelgrass polygon id and potential eelgrass polygon id.  Features can be symbolized by the Density attribute, which describes the pervasiveness of eelgrass at a particular point location.  A single point symbology can also be used whereby no classifications or unique features are displayed.
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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?

    Kevin O'Brien
    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3034 (voice)
    860-424-4054 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time
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Why was the data set created?

The purpose of this datalayer is to depict the point locations of observed eelgrass and potential eelgrass growth along Connecticut's coast and in Long Island Sound.  The polygon layers created from these points are the Observed and Potential Eelgrass Beds.  This layer is not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.)

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How was the data set created?

  1. Where did the data come from?

    Source 1 - GPS Data Files and Field Notes (source 1 of 3)

    Dr. Charles Yarish, University of Connecticut (Stamford), 1997, GPS Data Files and Field Notes: State of Connecticut, .

    Other citation details:
    The points generated in this source were created by GPS equipment and field notes.

    Type of source media: GPS file, field notes
    Source scale denominator: 24000
    Source contribution:
    The GPS data that was collected during the creation of this layer also included field notes and corrections to some GPS point locations that were not accurately depicted due to equipment malfunction or satellite reception loss.  

    Source 2 - Eelgrass Sample Points Coverage (source 2 of 3)

    University of Connecticut, Long Island Sound Resource Center, University of Connecticut, State of Connecticut, Department of Environmental Protection, 1997, Eelgrass Sample Points Coverage.

    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    This data source refers to all features combined in one statewide layer. Since initial publication in 1997, subsequent publication of the layer was generated by the State of Connecticut in order to convert from NAD 27 to NAD 83. Consequently, a different copy of this layer was produced, representing the change in the state plane coordinate system.  Changes made to the entire layer are reflected in metadata process steps where this particular data source is cited as both the Source Used and the Source Produced.

    Source 3 - Eelgrass Sample Points Shapefile (source 3 of 3)

    State of Connecticut, Department of Environmental Protection, 1997, Eelgrass Sample Points Shapefile.

    Online links:
    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    This source represents the final form of Eelgrass Sample Points and was produced from the Eelgrass Sample Points ArcInfo Coverage.

  2. What changes have been made?

    Date: 1993-1995 (change 1 of 3)
    Feature digitizing and attribution (GPS method) - During the 1993-1995 field seasons a team of researchers lead by Dr. Charles Yarish of the University of Connecticut  Dept. of Ecology and Evolutionary Biology surveyed over 800 potential eelgrass locations along the Connecticut coast using a Global Positioning System (GPS), SCUBA, and a 20' boat. The GPS system used was not explicitly recorded.  Their GPS coordinates and field notes were used to create a GIS point coverage which was plotted and checked on a 1:24,000 scale base map of the Connecticut shore. These point locations and field observations, in conjunction with the nearshore bathymetry, were then used to delineate areas representing both observed and potential eelgrass beds. The sample points represent GPS collected Latitude/Longitude coordinates (in decimal minutes)  that were projected to Connecticut State Plane coordinates and plotted on 1:24,000 scale digital hydrography and bathymetry layers. Where the original coordinates (hand-recorded) appeared to be in error (due to either human error, bad satellite reception, or inconsistency with the 1:24,000 scale hydrography or bathymetry) the location of the point was altered (based on field note descriptions and memory) to fit the hydrography.  Points are noted in the PLOT_LOC attribute as altered or original.

    Person responsible for change:
    Mary DiGiacomo-Cohen
    University of Connecticut, Long Island Sound Resource Center
    860-405-9015 (voice)

    Data sources used in this process:
    • Source 1 - GPS Data Files and Field Notes

    Data sources produced in this process:
    • Source 2 - Eelgrass Sample Points Coverage

    Datum conversion - Using ESRI ArcInfo software, the Eelgrass Sample Points layer was converted from the Connecticut State Plane Coordinate System of 1927 (NAD27) to the Connecticut State Plane Coordinate System of 1983 (NAD83). The NADCON (North American Datum CONversion) data transformation was used.

    Person responsible for change:
    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, CT 06106
    United States

    860-424-3540 (voice)
    860-424-4058 (FAX)

    Data sources used in this process:
    • Source 2 - Eelgrass Sample Points Coverage

    Data sources produced in this process:
    • Source 2 - Eelgrass Sample Points Coverage

    Date: 1997 (change 3 of 3)
    Using ArcView software, the Eelgrass Sample Points Coverage was converted to Shapefile format.

    Person responsible for change:
    State of Connecticut, Department of Environmental Protection

    Data sources used in this process:
    • Source 2 - Eelgrass Sample Points Coverage

    Data sources produced in this process:
    • Source 3 - Eelgrass Sample Points Shapefile

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

  1. How well have the observations been checked?

    Attribute accuracy is unknown.

  2. How accurate are the geographic locations?

    Horizontal accuracy is unkown for this layer.  However, the data in this layer is only as accurate as the global positioning satellite (GPS) system used to compile the data.  The majority of points were compiled with GPS; some were altered and re-plotted due to equipment malfunction or satellite reception problems.  The PLOT_LOC attribute denotes whether or not a point feature was altered.

  3. How accurate are the heights or depths?

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

    The completeness of the data reflects the feature content of the data sources, which includes the GPS data files and field notes.  The Eelgrass Sample Points layer is complete in the sense that it accurately reflects the contents of the above referenced source information available at the time the State of Connecticut, Department of Environmental Protection created the layer. However, compared to current conditions, this layer is incomplete and is not updated.

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

    Logical consistency of this layer is unknown.  

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How can someone get a copy of the data set?

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

Access constraints: None. The data is in the public domain and may be redistributed.
Use constraints:
None. No restrictions or legal prerequisites for using the data.  Note, the data is not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.)  Once acquired, any modification made to the data must be noted in the metadata. When printing this information on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection as the source for this information.

Distributor 1 of 1

  1. Who distributes the data set?

    State of Connecticut, Department of Enviromental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3034 (voice)
    860-424-4054 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

  2. What's the catalog number I need to order this data set?

    Eelgrass Sample Points

  3. What legal disclaimers am I supposed to read?

  4. How can I download or order the data?

    • Availability in digital form:


    • Data format:
      in format Shapefile, Feature Class (version ArcGIS)
      Network links:http://www.ct.gov/deep

    • Cost to order the data: An online copy of the data may be accessed without charge.


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

    The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.

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

    Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

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Who wrote the metadata?

Dates:
Last modified: 20120119

Metadata author:
Jacqueline Mickiewicz, Mary DiGiacomo-Cohen
State of Connecticut, Department of Environmental Protection
79 Elm Street
Hartford, Connecticut 06106-5127
USA

860-424-3540 (voice)
860-424-4058 (FAX)
dep.gisdata@ct.gov
Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

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

Metadata extensions used:
  • http://www.esri.com/metadata/esriprof80.html

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