Black-and-white aerial photography at a scale of 1:24,000 was the principal source of information used to assess distribution and abundance of SAV in Chesapeake Bay, its tributaries, and the Delmarva Peninsula coastal bays from Assawoman Bay to Magothy Bay in 2013. There were 167 flight lines that yielded aerial photography negatives that were scanned and orthorectified to create orthophoto mosaics. These mosaics were carefully examined on-screen and outlines were drawn to identify all SAV beds visible on the photography, providing a geographic information system (GIS) digital database for analysis of bed areas and locations.Ground survey information collected in 2013 was tabulated and entered into the VIMS SAV GIS digital database.

The aerial photography is carefully examined to identify all visible SAV beds. Photographs covering SAV beds are scanned and orthorectified to create orthophoto mosaics. Outlines of SAV beds are then interpreted on-screen, providing a digital database for analysis of bed areas and locations. Ground survey information collected in 2013 is tabulated and entered into the SAV geographic information system (GIS). SAV distribution data are presented and discussed based on the 2003 revised Chesapeake Bay Program (CBP) segmentation and zonation scheme (DAWG, 1997). This segmentation scheme is mapped and listed by salinity regime.

The CBP Segmentation scheme defines 93 segments that are grouped into four salinity zones to reflect the communities of SAV species found in the Chesapeake Bay: Tidal Fresh (less than 0.5 ppt), Oligohaline (0.5-5 ppt), Mesohaline (5-18 ppt), and Polyhaline (18-25 ppt).

SAV distribution in the Delmarva Peninsula coastal bays is presented and discussed separately from Chesapeake Bay. A fourth zone, the Delmarva Peninsula Coastal Bays Zone, is defined to include the region from Assawoman Bay to Magothy Bay and is subdivided into ten segments: Assawoman, Isle of Wight, Sinepuxent, Chincoteague, Burtons, Hog Island, Spidercrab,Cobb, South, and Magothy bays.