Data Management Plan

This data set contains sensitive biological resource data for submerged aquatic vegetation (SAV) in Chesapeake Bay and the Outer Coasts of Maryland and Virginia. Vector polygons in this data set represent SAV distribution. Species specific abundance, seasonality, status, life history, and source information are stored in relational data tables (described below) designed to be used in conjunction with this spatial data layer. This data set comprises a portion of the ESI data for Chesapeake Bay and the Outer Coasts of Maryland and Virginia. ESI data characterize the marine and coastal environments and wildlife by their sensitivity to spilled oil. The ESI data include information for three main components: shoreline habitats, sensitive biological resources, and human-use resources.

This reflects the extent of all land and water features included in the overall Chesapeake Bay and Outer Coasts of Maryland and Virginia 2016 ESI study region. The bounding box for this particular feature class may vary depending on occurrences identified and mapped.

Lineage Statement:
This atlas supersedes two separate first edition atlases, Virginia (2005, #25) and Maryland (2007, #47). Three main sources of data were used to depict benthic distribution and seasonality for this data layer: 1) personal interviews with resource experts from the Virginia Institute of Marine Science (VIMS) and U.S. Fish and Wildlife Service (USFWS), 2) digital survey data from VIMS and USFWS, and 3) published reports.

Process Steps:

• 2016-09-01 00:00:00 - SAV data for the Chesapeake Bay from 2010-2014 aerial surveys were provided by VIMS. VIMS categorized SAV density for each year for all survey locations using a scale from 1 = very sparse (<10% coverage), to 4 = dense (70-100% cover). For the ESI, VIMS provided five years (2010-2014) of SAV data to account for interannual variation in bed size and density. The five years of data were layered and the resulting polygons were categorized as either high or low density based on whether a majority of the years (three or more years) had high density categories (3 or 4) or low density categories (1 or 2). Areas with a density category of 0 for all five years were not mapped. Areas with one or two 0 density years were assigned to the ESI high or low categories based on the density categories of the majority of remaining years. All areas with at least one year of SAV presence, regardless of density value, that was not already covered by the high and low polygons were mapped with a concentration of ephemeral. High, low, and ephemeral polygons were dissolved to make contiguous polygons. Density of all SAV communities in Chesapeake Bay peak in the summer months, and some species are present year-round. The SAV survey data provided was not species-specific, so all SAV mapped in the Chesapeake Bay were mapped as present year-round. SAV in Back Bay was mapped where present using the SAV map of North Carolina and Southeastern Virginia originated by the North Carolina Division of Marine Fisheries and provided by Back Bay NWR. Freshwater SAV communities defoliate and are not present in winter, so SAV in Back Bay, an oligohaline bay, were mapped only during months present for freshwater SAV. The above digital and/or hardcopy sources were compiled by the project biologist to create the BENTHIC data layer. Depending on the type of source data, three general approaches are used for compiling the data layer: 1) information gathered during initial interviews and from hardcopy sources are compiled onto U.S. Geological Survey 1:24,000 topographic quadrangles and digitized; 2) hardcopy maps are digitized at their source scale; 3) digital data layers are evaluated and used "as is" or integrated with the hardcopy data sources. See the Lineage section for additional information on the type of source data for this data layer. The ESI, biology, and human-use data are compiled into the standard ESI digital data format. A second set of interviews with participating resource experts are conducted to review the compiled data. If necessary, edits to the BENTHIC data layer are made based on the recommendations of the resource experts, and final hardcopy maps and digital data are created.

Data can be accessed by downloading the zipped ArcGIS geodatabase from the Download URL (see Distribution Information). Questions can be directed to the ESI Program Manager (Point Of Contact).