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, its tributaries, and the Delmarva Peninsula coastal
bays from Assawoman Bay to Magothy Bay in 2015. There were 186 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 2015 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 2015
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.