|Monitoring Submerged Aquatic Vegetation|
Surveys track the health and recovery of submerged aquatic vegetation (SAV) in the Chesapeake Bay and guide protection and restoration efforts. The Virginia Institute of Marine Science (VIMS) maps and measures SAV beds in the Chesapeake Bay annually using aerial photography and has produced reports most years since 1984. The sample photo below shows SAV beds as dark areas. Because of the importance SAV plays in providing critical habitat for Bay species, NOAA provides financial and technical support for such work. Additional data collected by NOAA Chesapeake Bay Office staff members and others are added to the maps produced by the Virginia Institute of Marine Science.
Analysis enabled by survey work shows that the Bay-wide acreage of SAV hit a low point around 1984, but increased through 1993. Since then, acreage has leveled off at about 40% of the Bay-wide restoration goal of 185,000 acres set by the Chesapeake Bay Program in 2003. Reasons for this leveling off are not clear; it appears that recent increases in SAV in the lower-salinity, upper Bay (a fairly small area) have been counterbalanced by losses of SAV in the higher-salinity lower Bay (a much larger area).
A recovery in SAV is linked to improved water quality in many areas of the Chesapeake, as federal, state, and local cleanup efforts take effect. SAV is an indicator of good water quality because it is abundant only where nutrient levels are low and water clarity is high. Survey results also identify SAV beds that need protection (i.e., where dredging, pier construction, or other potentially damaging activities are planned).
Individual citizens and community organizations can help with SAV surveys; contact your local watershed organization for more information. Generally, citizens in small boats visit, or “ground truth,” SAV beds that have been mapped by the aerial survey (see this poster from 2010 about survey methods). Citizen volunteers confirm the presence of SAV, identify the species if possible, and locate beds too small to be seen from the air.