North & South Rivers Watershed Association

Scientists Meet to Save Eelgrass

Eelgrass was a big discussion topic on the South Shore on January 31st. Our Waterwatch Lecture Series featured Kathryn Ford of Mass. Division of Marine Fisheries (MassDMF) discussing eelgrass, and earlier in the day our Watershed Ecologist co-hosted a workshop with MassDMF to come up with a plan for monitoring eelgrass in the Duxbury, Kingston, and Plymouth Bay complex. The workshop was funded by EPA and MassBays.

Eelgrass is an important coastal habitat, much like salt marsh or shellfish beds. It is not a true grass or an algae (seaweed), but a flowering plant. It is important because its roots and leaves help hold sediment in place, it forms the base of parts of the food web in estuaries, it holds carbon from the atmosphere, and provides shelter.

Unfortunately, there have been major losses of eelgrass in Duxbury, Kingston, and Plymouth. Between 1995 and 2014, 56% of the eelgrass acreage was lost. More recently, 29% of the remaining acreage was lost between 2014 and 2017. The causes of this loss are being investigated, and it has become important to start monitoring the eelgrass to detect additional loss and try to connect it to possible causes.

The workshop on January 31st brought together federal and state agencies, university researchers, town staff, and interested stakeholders like oyster growers to discuss monitoring options and develop a plan. The end result was the use of multiple types of monitoring, some which (mapping eelgrass using photos taken from planes and using sonar fishfinders from boats) are already happening. In addition to the photos taken from planes, which happens every few years and covers a large area with relatively low detail, the group also decided to monitor random points throughout the bays. These points will be chosen randomly using a grid of hexagons to make sure they are spread out. The sampling will include taking a photograph of the bottom using a camera attached to a frame (shown here) and using that photograph to determine how much of that frame has eelgrass in it. The sonar mapping will collect similar information. Finally, divers will measure eelgrass plants in one small area to learn more about their health. The goal is to understand why the eelgrass is disappearing and see if it would be a good idea to try to restore it.

The monitoring will begin this spring. If anyone is interested in learning more about participating in some of the sampling, please contact Sara (sara@nsrwa.org).

     

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