Potential Eelgrass Beds is a 1:24,000 scale, polygon feature-based layer that depicts the locations of potential eelgrass beds in Long Island Sound, in major rivers, and within bays, harbors and other waterbodies along Connecticut's coast. The layer is based on information from the Observed Eelgrass Beds and Eelgrass Sample Points layers. It represents conditions at a particular point in time (1993 to 1995). During the 1993-95 field seasons a team of researchers from the University of Connecticut Dept. of Ecology and Evolutionary Biology led by Charles Yarish, equipped with a Global Positioning System (GPS), SCUBA, and a 20' boat surveyed over 800 potential eelgrass locations. Their GPS coordinates and field notes were used to create a point coverage entitled Eelgrass Sample Points, which was plotted and checked on a 1:24000 scale base map of the Connecticut shore. These point locations, observations, and the nearshore bathymetry were then used to delineate areas representing both observed and potential eelgrass beds. Eelgrass beds were initially digitized at 1:24,000 scale, but have been edited and revised on screen at higher resolution. Potential beds, where not individually delineated, were created by buffering observed beds a distance of 33 feet (10 meters). These buffered polygons were intersected with buffered (distance of 5 ft.) shoreline arcs to keep potential polygons a minimum distance off the shoreline. These potential beds are considered to be areas where eelgrass is likely to spread to under ideal conditions, where eelgrass may exist in small isolated patches, where eelgrass may exhibit high temporal variability, or perhaps where restoration projects could be undertaken. Feature locations may not always be exact due to equipment failure or lack of satellite reception. In those cases, points were estimated from field notes. It should be noted that the Potential Eelgrass Beds layer is not a complete dataset of all potential eelgrass sites in Connecticut and/or Long Island Sound. This layer was published in 1997 and is not updated. It does not represent current conditions. There are 67 polygon features representing potential eelgrass beds in this layer. Geographic locations are as follows: westernmost areas: Clinton Harbor; easternmost areas: Little Narragansett Bay, Rhode Island waters. Potential beds range in size from .179 acre (318 sq. ft.) to 471 acres (20,551,582 sq. ft.). Potential beds contain 0 to 9 observed beds, and from 0 to 88.1% area covered by observed beds. The total area of potential beds is 2,196 acres.
For more information, refer to the Eelgrass Sample Points and Observed Eelgrass Beds layers.
ground condition
Potential Eelgrass Areas stored as digital vector data (Source: State of Connecticut, Department of Environmental Protection)
Internal feature number. (Source: ESRI)
Feature geometry. (Source: ESRI)
Percent of area covered by observed eelgrass beds. (Source: State of Connecticut, Department of Environmental Protection)
Number of point locations (Eelgrass Sample Points) within the polygon. (Source: State of Connecticut, Department of Environmental Protection)
Area of feature in acres (SHAPE_AREA divided by 43560). (Source: State of Connecticut, Department of Environmental Protection)
Feature geometry. (Source: ESRI)
Existence of potential eelgrass areas. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Y | Yes - potential eelgrass area exists. |
| N | No - Potential eelgrass area does not exist. |
Includes Potential Eelgrass Bed polygon features such as percent of area covered by observed eelgrass (P_OBSERV), existence of potential eelgrass areas (POTENTIAL), number of eelgrass sample point locations within the polygon (FREQUENCY), size of the feature in acres (ACREAGE), size of the feature in square feet (SHAPE_AREA), and perimiter of feature area (SHAPE_LENGTH).
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Potential Eelgrass Beds is 1:24,000-scale data. The purpose of this datalayer is to depict the locations of potential eelgrass growth along Connecticut's coast. The polygons in this layer were created from two source layers: Eelgrass Sample Points and Observed 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.)
This source served as the first of two major sources of base data for the creation of Potential Eelgrass Beds. GPS coordinates and field notes were used to create the Eelgrass Sample Points coverage, which was plotted and checked on a 1:24000 scale base map of the Connecticut shore. These point locations, observations, and the nearshore bathymetry were then used to delineate areas representing both observed and potential eelgrass beds.
This source served as the second of two major sources of base data for the creation of Potential Eelgrass Beds. The Observed Eelgrass Beds layer was used to create potential eelgrass beds by buffering observed beds a distance of 33 feet (10 meters). These buffered polygons were intersected with buffered (distance of 5 ft.) shoreline arcs to keep potential polygons a minimum distance off the shoreline.
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.
This source represents the final form of Potential Eelgrass Beds and was produced from the Potential Eelgrass Beds ArcInfo Coverage.
Feature Creation and Attribution - During the 1993-95 field seasons a team of researchers led by Charles Yarish, equipped with a Global Positioning System (GPS), SCUBA, and a 20' boat surveyed over 800 potential eelgrass locations. Their GPS coordinates and field notes were used to create a point coverage entitled Eelgrass Sample Points (Source 1), which was plotted and checked on a 1:24000 scale base map of the Connecticut shore. These point locations, observations, and the nearshore bathymetry were then used to delineate areas representing both observed eelgrass beds (Source 2) and potential eelgrass beds. Eelgrass beds were initially digitized at 1:24,000 scale, but have been edited and revised on screen at higher resolution. Potential beds, where not individually delineated, were created by buffering observed beds (Source 2) a distance of 33 feet (10 meters). These buffered polygons were intersected with buffered (distance of 5 ft.) shoreline arcs to keep potential polygons a minimum distance off the shoreline. These potential beds are considered to be areas where eelgrass is likely to spread to under ideal conditions, where eelgrass may exist in small isolated patches, where eelgrass may exhibit high temporal variability, or perhaps where restoration projects could be undertaken.
Datum conversion - Using ESRI ArcInfo software, the Potential Eelgrass Beds 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.
Using ArcView software, the Potential Eelgrass Beds Coverage was converted to Shapefile format.
Attribute accuracy is unknown.
The horizontal positional accuracy of this data is unknown.
The completeness of the data reflects the feature content of the data sources, which includes the GPS data files and field notes. This 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.
Logical consistency for this layer is not known.
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.
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| Data format: | in format Shapefile, Feature Class (version ArcGIS) |
|---|---|
| Network links: | http://www.ct.gov/deep |
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.
79 Elm Street