Yesterday the Chesapeake Bay Program released their annual report on the abundance of underwater vegetation, and several news agencies have been sharing the results. I heard a piece on WAMU this morning on the Chesapeake Bay Program’s findings. In the 2012-2013 timeframe, underwater grasses increased by 24%, and up to 12,000 acres. Widgeon grass was the most successful in the middle Bay over this period, (between the Honga River to Pocomoke Sound), while eelgrass saw a smaller recovery.
Widgeon grass and eelgrass are found in waters with higher salinity. As the Chesapeake has four different salinity zones, there are a variety of underwater grasses that grow in the bay. Grasses such as wild celery are found in the lower reaches of the Potomac River. Widgeon grass and eelgrass are found in the middle and lower bay.
(Image from virginiaplaces.org/watersheds/)/
Underwater grasses are extremely important to aquatic species and the overall health of the Chesapeake. The grasses are a food source and offer habitat for the Blue Crab and several fish species. The long-term trend of seagrass decline was credited as a potential reason for the low crab abundance in recent years. Juvenile crabs are more susceptible to predators in areas where the seagrass has disappeared. Grasses also help to prevent erosion, and absorb nutrients in the water. Underwater seagrass is threatened by polluted runoff and a lack of sufficient light.
The Virginia Institute of Marine Science (VIMS) does a lot of research on underwater grasses, and has been tracking their abundance in the bay for years. Their findings are included in the Chesapeake Bay Program report.