Submerged Aquatic Vegetation of Coastal Alabama - Fall Polygon Data (MBNEP Survey 2015)

This data set consists of digital vector data describing the location and species composition of submerged aquatic vegetation in coastal Alabama during fall 2015, including Mississippi Sound, Mobile Bay, Mobile-Tensaw Delta, Little Lagoon, Bay La Launch, Perdido Bay, and their communicating tributaries. The data set includes 1,068 orthophotograph frames and a MrSID mosaic produced from digital aerial imagery acquired on October 10 through 15. SAV was concentrated in upper Mobile Bay and the Mobile-Tensaw Delta, Mississippi Sound, and the Perdido Key area of southeast Baldwin County. Most of the 2015 SAV acreage occurred in the lower Mobile-Tensaw Delta, particularly in the Bridgehead Quadrangle, which contained 63% (4,984.8 ac) of the total 7,923.1 acres mapped. Other areas of substantial acreage included the Mobile Quadrangle (929.2 ac) in the Delta and the Grand Bay Quadrangle (413.5 ac) in Mississippi Sound. 60 percent of the total SAV acreage (4,792.0 acres) was mapped as continuous (>50%) coverage. Overall, there were 1,201.2 fewer acres mapped in fall 2015 than in the 2015 summer survey. The decrease was mostly due to a 920.2-ac decrease in the Bridgehead Quadrangle and a 203.1-ac decrease in the Daphne Quadrangle. In addition to a fall decrease in the overall extent of SAV, there were changes in the proportion of patchy SAV in fall (40%) compared to the summer (22%), particularly in upper Mobile Bay and the lower Delta, Of the 28 habitat categories, most were comprised of mixtures of species occurring in oligohaline systems of the study area.