Historic Eelgrass Points is a 1:24,000-scale, point feature-based layer that depicts the locations of historic eelgrass beds (Zostera marina) in Long Island Sound, the Connecticut River, the Quinnipiac River and other bays, harbors and waterbodies in Connecticut's coastal area. It also includes several points located along the north shore of Long Island. There are a total of 131 point features, the majority of which are located east of the Connecticut River. Point features in this layer are compiled from two major sources: 1) the polygon feature label points in the Historic Eelgrass Beds polygon layer representing sources with a mapping component; and 2) additional points that were based on historic literature review that had no mapping component. Source information including source description and collection date for each point is described in the layer's table data. Feature locations are inexact. Because of the variety of source maps and methods used for their automation, this coverage should be considered to have limited spatial accuracy and is appropriate for general uses only. Actual data collection ranged from 1873 through 1996. This layer was published in 1997 and is not updated. It does not represent current conditions.
Some of the points in this layer were taken from the label points in the Historic Eelgrass Beds polygon layer. The remaining points were collected from literature review. Refer to the Historic Eelgrass Beds polygon layer for more information.
ground condition
Historic Eelgrass Beds represented as point features (Source: State of Connecticut, Department of Environmental Protection)
Internal feature number. (Source: ESRI)
Feature geometry. (Source: ESRI)
Year or span of years eelgrass observed in area. (Source: State of Connecticut, Department of Environmental Protection)
A brief description of the eelgrass bed's location; may include notation of sample station. In most cases the location description is similar to the description given in the original literature, and indicative of the level of detail given by the source listed. (Source: State of Connecticut, Department of Environmental Protection)
Refers to source of information (see bibliography in Source 2 Citation Information) for a particular location. In cases where a personal communication is noted, generally that person communicated with R. Rozsa or C. Yarish for the puspose of their respective reports, not for the purpose of this digital compilation. (Source: State of Connecticut, Department of Environmental Protection)
Existence of eelgrass and/or type of transplant. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Y | Yes |
| N | No |
| D | Detritus |
| F | Failed transplant |
| P | Successful transplant |
| T | Transplanted, outcome unknown |
Mapped points are those whose location was digitized or interpreted from a published map. General points are those who location was determined by text description only, and my have been placed centrally within the waterbody described (if the description was simple such as "Mumford Cove") and not necessarily where eelgrass would be likely to have grown. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| M | Mapped - digitized or interpreted from a map. |
| G | General - location derived from text reference. |
Indicates whether an eelgrass polygon feature exists for that point in the Historic Eelgrass Beds layer. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| 1 | Polygon exists |
| 0 | Polygon does not exist |
Includes Historic Eelgrass point features such as date of eelgrass observation, location of eelgrass, source of data, transplant type, eelgrass source type, and a flag attribute for the existence of an eelgrass polygon in the Historic Eelgrass Bed polygon layer. Features can be symbolized by the Eelgrass attribute, which describes the type of eelgrass transplant, or by the Type attribute, which describes the mapping type used.
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Eelgrass Historic Points is 1:24,000-scale data. It depicts the location of eelgrass beds that existed historically at dates specified in the attribute data. Use this layer with other 1:24,000-scale map data only, to provide a general indication of historic eelgrass distribution. This layer can also be used with the following layers: Historic Eelgrass Points, Observed Eelgrass, Potential Eelgrass, and Eelgrass Sample Points. 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.)
The label points from the Historic Eelgrass Beds polygon layer provided some of the data for the Historic Eelgrass Points layer.
Consists of maps, reports, written memoranda, and historic literature that reference the approximate locations of eelgrass existing at a particular point in time. The literature reference for each point is described in the Source attribute in the data table. These sources are listed below. Bibliography Abate, 1994, personal communication to R. Rozsa. Addy,C.E., and Johnson,R.H., 1947, Status of eelgrass along the Atlantic coast during 1947. Proc. N.E. Game Conference. 73-78. Barrett,J.M., 1991, Untitled compilation of eelgrass beds prepared by the Nature Conservancy for the Natural Resources Center, DEP. Barske,P., 1993, personal communication to R. Rozsa, excerps from his personal diary. Beckley,B., 1982, Transcript record from a DEP public hearing. Brown,L.K., 1996, personal communication to M. DiGiacomo-Cohen, description of New York State Department of Environmental Conservation observations of eelgrass populations around Fishers Island, NY. Conard,H.S., 1935, The Plant Associations of Central Long Island: A study in descriptive plant sociology. The American Midland Naturalist. 16(4). Cottam,C., 1945, Eelgrass conditions along the Atlantic seaboard of North America. Plant Dis. Reptr. 29:302-310. Cottam,C., and Addy,C.E.,1947, Present eelgrass condition and problems on the Atlantic coast of North America. Trans. N. Amer. Wild. Conf. 12:387-398. Cottam,C., and Munro,D.A., 1954, Eelgrass Status and Environmental Relations. J. of Wildlife Management. 18(4):449-460. Crawford,H., 1989, Scientific literature review: An investigation of sediment conditions of Quiambog and Wilcox COves in Stonington, CT, in Crawford, H.M., Aftab, K.M., Historical and environmental survey of Quiambog and Wilcox COves in Stonington , CT, a report in two parts submitted to the Board of Selectmen, Town of Stonington, Stonington Shellfish Commission. Department of Environmental Protection Marine Fisheries, 1994, personal communication to R. Rozsa. Johnson,D.S., and York,H.H., 1915, The relation of plants to tide-levels. A study of factors affecting the distribution of marine plants. Carnegie Institution of Washington No. 206, 143 p. Knapp,P., 1995, personal communication to C. Yarish. Knight,J.L., and Lawton,R.B., 1974, Report on the possible influence of thermal additions on the growth of eelgrass (Zostera marina) in Jordan Cove, Waterford, Connecticut. Report to Northeast Utilities Service Company. Lewis,R.S., 1995, personal communication to C. Yarish. Lynch,J.W., and Cottam,C., 1937, Status of eelgrass (Zostera marina) on the North Atlantic coast, January, 1937. Wildlife Research and Management. BS-94:1-15. Nichols,G.E., 1920, The vegetation of Connecticut. VII. The associations of depositing areas along the seacoast. Bulletin Torrey Botanical Club. 47:511-548. Northeast Utilities Environmental Laboratory, 1990, Monitoring the Marine Environment of Long Island Sound at Millstone Nuclear Power STation, Waterford, Connecticut. Annual Report 1989. Renn,C.E., 1937, The eel-grass situation along the middle Atlantic coast. Ecology. 18:323-325. Rozsa,R., 1994. Long term decline of Zostera marina in Long Island and Fishers Island Sounds. unpublished report. St. John,H., 1920, Additions to the flora of Fishers Island. Journal Rhodia. Tolderlund,D.S., 1975, Ecological Study of the Thames River Estuary (Conn.) in the Vicinity of the U.S. Coast Guard Academy, Report No. RDCGA 575. Transeau,E.N., 1913, The vegetation of Cold Spring Harbor, Long Island. I. The littoral successions. Plant World. 16:189-209. Tucker,G., and Horning,E.H., 1996, personal communication to S. Mickolyzck, description of New York State Museum collection trip in 1990. Uhler,F.M., 1932, unpublished report: Report on the examination of certain waterfowl feeding and breeding grounds in Connecticut, Aug. 2 to 5, 1932. 33 p. U.S. Coast and Geodetic Survey, 1892, Milford to Bridgeport, Conn., no. 1567, scale 1:10,000. U.S. Dept. of Commerce, 1918, North shore of Long Island Sound, Guilford Harbor to East Haven River, no. 217, scale 1:20,000. U.S. Dept. of Commerce, 1925, North shore of Long Island Sound, Goshen Point to Hatchett Point including Niantic Bay, no. 214, scale 1:20,000. U.S. Dept. of Commerce, 1933, Thames River, Harbor of New London and approaches, no. 359, scale 1:20,000. U.S. Dept. of Commerce, 1958, Fishers Island Sound, no. 358, scale 1:20,000. U.S. Dept. of Commerce, 1965, Fishers Island Sound, no. 358, scale 1:20,000. Welsh,B.L., 1980, A study of Jordan Cove: its hydraulic character, sediment and macrophyte distributions as related to shoaling. Final draft report submitted to Commissioner of Environmental Protection, Department of Environmental Protection, State of Connecticut, 80 p. Welsh,B.L., Bohlen,W.F., and Buck,J.D., 1985, An Investigation of Impacts Produced by Settling Basin Discharges on the Copps Brook/Quiambog Cove System, Preliminary Report. Submitted to The Connecticut American Water Company. Welsh,B.L., and Stewart,L., 1984, The Effects of Energy-related Transport Activities on Benthic Marine Plants, Fish, Shellfish, and Lobsters in the Thames River Estuary. Final report to the Office of Policy and Management, State of Connecticut.
The result of the compilation of label points from Sources 1 through 3.
This source represents the final form of Historic Eelgrass Points and was produced from an ArcInfo coverage.
Feature digitizing and attribution (feature selection method) - Using ESRI ArcInfo software, the label points in the Source layer were copied to the Historic Eelgrass Points layer. These features were then assigned a value of "1" in the P_FLAG attribute field to denote their migration from the Historic Eelgrass Beds coverage. No accuracy checks were performed since the features were electronically copied from one layer to another. Points represent some previously described distributions of Zostera marina (eelgrass). Most points were digitized on screen using a 1:24,000 scale hydrography base, with the exception of points transferred from the eelgrass historic beds coverage (P_Flag = 1) which were digitized off 1:24,000 scale USGS topographic quadrangle maps. Because most points were entered based on a general description or were "fitted" from maps of various scales (see bibliography in Source 1 citation information), this coverage should be considered to have limited spatial accuracy and is appropriate for general uses only. This digital compilation is based for the most part on a literature review by Ron Rozsa (CT DEP) and Ruth Linden / Charles Yarish (UCONN Stamford), and Mary DiGiacomo-Cohen (LISRC) and is not presumed to be a comprehensive representation of the pre-1993 distribution of Zostera marina.
Feature digitizing and attribution (heads up digitizing method) - Using ESRI ArcInfo software, features from Source 2 - Literature Research, were manually digitized on the screen (heads-up digitizing) at a 1:24,000 scale onto a hydrography based background map. These features were then assigned a value of "0" in the P_FLAG attribute field to denote that their original source was not the Historic Eelgrass Beds polygon layer. Accuracy checks were applied only insofar as verifying the point location from Source 2. Note that the locations of these points are considered approximate due to the ambiguity of the locational references in the source data.
Datum conversion - Using ESRI ArcInfo software, the Historic 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 3, the Historic Eelgrass Points Coverage was converted to a Shapefile format.
Attributes were derived from literature review and checked by the compiler and other reviewers (or co-authors) in a consistent manner. Since attributes were derived from multiple sources the accuracy of reporting or consistency of observations is likely to vary.
Because of the variety of the source information and the methods used for their compilation, this data should be considered to have very limited spatial accuracy and is appropriate for general uses only. (1:24,000 scale at best). Please note whether the point is attributed as 'mapped' or 'general' in the TYPE field. Mapped locations have been fit to 1:24,000 scale bases, general locations are based on text descriptions of varying detail and may be representative of a very general area such as a large cove or embayment.
The completeness of the data reflects the feature content of the data sources, as noted in the Source attribute in the data. These sources include paper maps, reports and memoranda. The Historic Eelgrass Point layer is complete in the sense that it accurately reflects the contents of the source information available at the time the State of Connecticut, Department of Environmental Protection created the layer. This data is not updated.
Historic data is assumed to be complete for the set of literature reviewed; however, additional historic references to eelgrass locations may exist. The data is not presumed to be a comprehensive representation of pre-1996 eelgrass distribution. Refer to Source Information for a list of historic references for this data.
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.
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