Multispectral aerial imagery with a ground sample distance of 24cm was the principal source of information used to assess distribution and abundance of SAV in Chesapeake Bay and its tributaries in 2016. There were 171 flight lines that yielded aerial imagery frames that were 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 2016 was tabulated and entered into the VIMS SAV GIS digital database.

The aerial imagery 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 2016 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).