you're reading...

Climate Change

Old Bay of Fundy dykelands could sequester massive amounts of carbon if restored to saltmarsh


Blue Carbon

Blue carbon is a term scientists use to describe the organic material contained within all the living organisms and soil found in coastal ecosystems. Together, this organic matter, combined with the carbon contained in land-based systems, makes up the stored portion of the Earth’s carbon budget. Climate change scientists hope to protect these two reservoirs of carbon, because the carbon that remains stored in land or coastal systems translates into less carbon released to the atmosphere, where it contributes to further warming.

An American salt marsh, by the U.S. Fish and Wildlife Service.

Wetlands are known to store large amounts of carbon, making them essential carbon sinks in the global greenhouse gas budget. Wetland plants take in carbon dioxide, grow fast, then die and decompose in low-oxygen conditions, meaning they take in much more carbon than they release. Saltmarshes are also particularly good at trapping carbon from outside the wetland, as marsh grasses slow and catch sediment traveling inland with the tide. Sediment (or soil) is basically decomposed plant and animal material, so it’s also made of carbon, and capturing the floating particles means the wetland accumulates this outside carbon as well as that from its own decaying plants. They’re so effective at this task, that saltmarsh soils accumulate carbon faster than any type of forest (about 40X more, on average!).


Marshes do more than just secure carbon

A 1915 photograph of the dykelands in Grand Pre Nova Scotia, on the Bay of Fundy, previously extensive salt marshes. By AL Hardy in the Kings County Museum.

They buffer us from the effects of climate change too; filtering storm runoff, slowing flood waters, and providing habitat for an increasingly threatened biodiversity.

Saltmarshes, like many wetlands however, are under threat by continued coastal development. In Europe, dyking (mound- or berm-building) of marshland for agricultural and defence purposes has been occurring since Roman times. Marshland isn’t suitable for settlement or European-style agriculture, and was (and still is in some places) viewed as wasteland. In Eastern North America, saltmarshes starting being dyked 400 years ago for use by settler farmers. In Canada and the United States today, there are still areas where a lack of wetland conservation policy facilitates the continued loss of these vital habitats along with the valuable goods and services they offer us. At this point, an estimated 77% of saltmarsh on the Bay of Fundy has been drained, while an estimated 25-50% of saltmarsh has been lost globally.


New Approaches

In some coastal regions, environmental managers and city planners are experimenting with softer methods for managing their shorelines. Instead of maintaining dykes, sea walls, and other hard defences, which are increasingly expensive under rising sea levels and increased storms, many are turning to saltmarsh restoration to provide a buffer for the areas they need to protect. In most cases, these are relatively simple projects, as simply returning the natural tidal flow to a dyked field can promote the return of protective saltmarsh vegetation.

The Bay of Fundy at high and low tide, by NASA Earth Observatory

Researchers have some idea how much carbon is stored in wetlands restored more than 10 years ago, but we know very little about the initial phase after restoration, where the wetland is changing very quickly from a farm field to vegetated marsh. A group of researchers from the University of McGill and Mount Allison University in Canada recently explored the stored carbon in a wetland outside Aulac New Brunswick, restored from dykeland by Ducks Unlimited Canada in 2010. There, two dykes were opened in a few locations along the berm to let in tidal flow from the Bay. The researchers collected sediment cores from the newly flooded fields for 6 years, and tested the amount of organic matter using a method called Loss on Ignition (which is basically where they light the tube of dirt on fire and see what’s left behind, it’s one of the perks of mud science!)

They found that overall carbon sequestration was very high, about 5X higher than a nearby saltmarsh that’s already transformed into a naturalized wetland after restoration more than 10 years ago. They also found that most of this carbon storage resulted from carbon secured from outside the marsh, as opposed to the decomposition of wetland vegetation within the marsh. Remember that wetland vegetation has to colonize newly flooded fields, and takes some time to decompose. It’s not surprising then that the massive rise in stored carbon over the few years post-restoration is therefore attributable to the incoming sediment caught by the vegetation. This has important implications for strategic carbon sequestration by environmental managers though.

Carbon accumulation decreases over time in restored wetlands, as sediment fills in all the available spaces and the marsh starts to accumulate carbon mainly by decomposition. The initial stage after restoration therefore is crucial for capturing the most carbon. In the Bay of Fundy, this stage is especially important because of the exceptional tides and high sediment load in the Bay’s waters. The Bay of Fundy is a natural haven for carbon sequestration, if all that sediment ends up in the right place (like a saltmarsh). The researchers suggested that the simple design of the restoration, by opening only a few holes in the dyke, was important for giving sediment places to accumulate amongst the spreading vegetation. Without the restoration, the incoming sediment would have landed in nearby mudflats or in the open ocean, where the carbon is less efficiently stored.


Credit for Carbon

A mud flat on the Bay of Fundy in New Brunswick, by Wladyslaw

As carbon credits roll into swing and these projects begin to be viewed from a more critical financial perspective, it will be important for wetland managers to understand how much carbon these restored marshes are storing, and how that might change over time. Carbon trading could open up large funding pots for wetland restoration projects that benefit people and wildlife alike.

Using the 2017 California carbon market price, the DUC project resulted in ~US$124,000 worth of off-set credits. Under the voluntary market, this amount falls to ~US$30,000. Either way, it’s an impressive calculation considering that saltmarshes aren’t currently recognized as an approved offset method in any of the regulated American markets, and Canada hasn’t yet picked up a market.

Imagine if every farmer, every municipality, and every landowner with that “useless” wet piece of land next to the river, had incentive to restore and protect their wetlands. Shortly after a simple dyke breaching, restored marshes along the Bay of Fundy sequester massive amounts of carbon, and provide ongoing buffering and habitat creation services. All that from a couple hours on a dozer!


Wollenberg JT, Ollerhead J, Chmura GL (2018) Rapid carbon accumulation following managed realignment on the Bay of Fundy. PLoS ONE 13(3): e0193930. https://doi.org/10.1371/ journal.pone.0193930


No comments yet.

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 6 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 9 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 9 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 11 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 12 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com