Port Royal Sound Foundation is hosting an event called Marsh Madness this month to celebrate the bounty of our marshes and the return of spring. It’s a fun play on words, but it’s also intended as a literal reminder that our salt marshes start cranking up this month, and that IS a reason to celebrate!
The Port Royal Sound watershed includes more than 100,000 acres of tidal salt marsh — that’s almost ⅓ of all of the salt marsh found in the state of South Carolina. And if you pay attention this month, you’ll notice that the endless expanse of marsh starts turning green again.
First, what exactly is a salt marsh? If you read last month’s Conservation Corner, you know that wetlands are areas where water covers the soil or is present either at or near the surface of the soil for different periods of time. A salt marsh is one type of coastal wetland that is flooded and drained by saltwater brought in by tides twice per day. There are two ‘zones’ of marsh – low marsh that is closer to the water and is submerged with every tide; high marsh which is submerged infrequently, typically only during peak high tides during full moons, spring tides and storm surges.
The vegetation found in salt marshes are halophytes, highly salt tolerant species. In the Port Royal Sound (and much of the southeastern US), the dominant species in our low marsh is smooth cord grass (Sporobolus alterniflorus), often called by its old taxonomic name, spartina. Look closely during the month of March, and you’ll start to see hints of green start to sprout in our currently dormant marshes. In high marsh, you start to see other species sprinkled in like pickleweed (Salicornia virginica) an edible salty treat and short form spartina a dwarfed variant. Go a little higher up, and you’ll get poked by black needle rush (Juncus gerardii) and surrounded by a beautiful patch of yellow flowers from sea oxeye daisy (Borrichia frutescens).
St. Helena State of Mind. Photo by Miles C. Sanders
With all of this vegetation, salt marshes are some of the most productive ecosystems found in the world. But what exactly do we mean by productive? Productivity, in this case, refers to the capacity of the system to produce nutrients and feed the energy cycle. The rich soil, abundant sunlight, and long growing seasons mean that all of these plants grow for probably three-quarters of the year, taking atmospheric carbon and converting it into plant material. That plant material serves as food and habitat for microorganisms, which feed larger and larger animals – a theory that is referred to as bottom-up ecology. That is what makes the Port Royal Sound an incredibly important body of water – it’s a critical source of food, refuge, and nursery habitat for a huge number of marine and terrestrial species.
Every fall, as temperatures drop and days get shorter, our endless green marshes turn to shades of gold to brown. Spartina dies back, and the dead vegetation creates a new layer of organic material on top of the mud. This plant material decays and becomes the newest installment to our pluff mud – the fine, dark, soupy mud so characteristic to the area.
Pluff mud represents millennia of sequestered carbon dioxide, built up based on season after season of marsh productivity. Scientists estimate that one acre of salt marsh can sequester or store 1,940 pounds of carbon each year (ESA). By that estimate, the salt marsh in the Port Royal Sound can sequester the equivalent of emissions from 10,120 cars each year (also makes you think twice about driving to get the mail!) So the next time you hear the term ‘blue carbon, ’ that’s what they are talking about – the incredible power of our marshes and other marine systems to convert or absorb atmospheric carbon dioxide and store it underwater and underground. We talk about the other incredibly valuable ecosystem services salt marshes provide in a future post, but know — they are worth WAY MORE than we can afford to replace!!
What is also important to recognize about salt marshes is that, over a long-ish time horizon, they move based on the level of the water! So as sea levels rise, salt marsh will naturally want to retreat further upland. If there are living barriers along the coastline like oyster reefs that allow sediment to build up behind those reefs, the elevation of marshes can rise up. If there are barriers in the way of allowing marshes to move upland — barriers like sea walls or causeways — those marshes can’t retreat and they will drown. So managing salt marsh MIGRATION is the name of the game in the Port Royal Sound.
The Port Royal Sound Foundation is a proud partner of the South Atlantic Salt Marsh Initiative (SASMI), a multi-state and cross-sector effort to conserve and protect salt marsh along the South Atlantic coast, along with several local and regional initiatives to restore living shorelines and to ensure salt marshes have room to move throughout the watershed.
So Marsh Madness!? YOU BET!
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