Great Bay Habitat Continued Decline In 2013
Data released Friday shows that a crucial piece of the ecosystem of the Great Bay estuary continued a seventeen-year downward trend.
Eel-grass is a big deal to the Great Bay. According to Rachel Rouillard, the executive director of the Piscataqua Region Estuaries Partnership (PREP), “eelgrass is like our canary in the coal-mine, it’s a fundamental underpinning of the health and vitality of the whole system.”
It filters the estuary and holds down sediment, keeping the water clear. It’s the habitat for the aquatic life that lives in the estuary. It has also declined by 58 percent since 1996, because of increased runoff, and nitrogen pollution from waste-water, fertilizers and other sources.
Last summer, PREP partnered with seven towns in the Great Bay region to fund a better type of photography to study eelgrass in the brackish water body. The higher quality camera was put into an airplane which flew over the bay at a higher altitude than previous years, and the photos were corrected for distortion afterward. The resulting images, which are accurate down to a resolution of one foot, can be used to study other issues facing the Great Bay, such as macroalgae blooms and salt-marsh extent.
But the first order of business was to tally up eel-grass extent, continuing a data set which began in 1980.
“We did find a slight decline in 2013, representing the third year of decline in a short term trend,” says Rouillard.
While year over year numbers can be deceiving, eelgrass declined by 90 acres over since 2012; the aquatic plant covered 1,683 acres in 2013, versus 1,891 in 2011 and 2,900 in 1996.
PREP will continue to use the better quality images in this year’s eel-grass survey, which is set to take-place next week.