Seagrass Decline Affects More Than The Environment

Jul 9, 2021

Credit APNEP

Coastal North Carolina is home to over 130,000 acres of submerged aquatic vegetation.  Some researchers say the coast might be in danger of losing up to half of that over the next decade. A decline in seagrass habitat affects more than the environment.   It also has lasting economic impacts, according to a new study.


Submerged Aquatic Vegetation, or SAV, is a crucial part of North Carolina’s coastal ecosystem. It contributes to water quality and shoreline stabilization. Tim Ellis, an ecologist with the Albemarle-Pamlico National Estuary Partnership, or APNEP, was involved in a recent study that found the amount of seagrass along our coast decreases between .5% and 5% each year. 

 

“One and a half percent per year is the global average for SAV decline. So in some parts of our estuary, the SAV is declining slower than the global average. But in some areas, particularly Bogue Sound where it's a more developed area, we have seen SAV declines in that global average, the one and a half, 1.7% range."

 

Several factors contribute to seagrass loss, including coastal development and reduced water quality. The study found that a decline in submerged vegetation could cost the state nearly $89 million over the next decade. Ellis said the reason for the study was to show North Carolinians the real costs of losing seagrass.

“Scientists and managers and the public all value coastal resources in similar and different ways. And to some folks, understanding the economic value is pretty meaningful in terms of their ability to appreciate the value of a resource.”

The study, funded by APNEP, was modeled closely on one conducted in the Chesapeake Bay four years prior. It considered four factors to calculate an estimate of the economic losses associated with the decrease in seagrass: commercial fisheries, recreational fishing, residential property values, and carbon sequestration.

Carbon sequestration is a plant’s ability to store carbon. As the amount of seagrass dwindles, more carbon is released into the atmosphere contributing to climate change. Carbon sequestration accounts for over half of the study’s projected economic losses - almost $56 million over a ten-year period. Researchers attached a per-acre social cost to the drop in sequestered carbon, said Sara Sutherland, an environmental economist at Duke University,

“The social cost of carbon just puts a monetary value on releasing a ton of carbon dioxide or CO2 into the atmosphere in terms of its costs in the future to property values and the cost of governments and taxpayers, the food system, and human health.”

The other three economic costs are less abstract. In the Albemarle-Pamlico Estuary, a single acre of SAV can support up to 40,000 fish. 

“With the value of the resources of fisheries habitat, we picked three species, blue crab, spotted sea trout, and red drum to look at the importance of SAV economically to those fisheries.”

Researchers calculated a loss of income of up to $10 million over the next decade for commercial and recreational fishers. According to Sutherland, that is a conservative estimate.   

“The number we have is a very low estimate because we only concentrate on a few species, two recreational species and one commercial species.”

Submerged vegetation also contributes to shoreline stabilization and prevents coastal erosion. If seagrass continues to disappear, homeowners along the coast might be forced to buy hardened or natural structures to stabilize their shoreline against flooding and storm surges. 

Legislation and investments in new technology are some of the things David Eggleston, Director of NC State’s Center for Marine Sciences and Technology said can be done to prevent seagrass die-off.  But homeowners along our coast can also do their part.

“We're seeing a tremendous amount of coastal North Carolina moving away from seawalls as a way to protect your property, to use of living shorelines. That's catching a lot of those nutrients and sediments that would be running off of the land, integrating those nutrients into saltmarsh plants, and then also providing habitat for a lot of juvenile fishery species.”

Boats can also be a threat to seagrass, said Ellis.

“When you're out on the water, you can be a good steward of the SAV resource by not driving your boat through SAV. It damages the resource physically. Trim your motor up, slow down, and try to avoid boating through areas with SAV.

Eggleston said that North Carolinians can improve the state’s water quality by upgrading their septic systems or managing the amounts of fertilizer that they use on their lawns. Small decisions like these can have a significant impact on a resource that is vital to the economy of Eastern North Carolina.