Climate Change

Eelgrass Fights

Seagrass is a powerhouse of blue carbon, accounting for 10% of the world’s blue carbon while only covering 0.2% of the ocean floor.

What is Blue Carbon?

Blue carbon refers to the carbon that our oceans absorb and retain. It is an essential service because carbon dioxide is a pollutant like toxic chemicals and plastics. Carbon dioxide enters the environment through burning biological materials, most commonly from fossil fuels. As a greenhouse gas, human-produced carbon dioxide is causing a rapidly changing global climate that affects us all.

Scientists and engineers are looking for solutions to slow the change in our climate. Blue carbon is a cost-effective natural climate solution that takes carbon out of our atmosphere [1]. Most technological solutions are not ready to implement and would be costly operations that would start small-scale.

Coastal habitats are already creating blue carbon. 83% of global carbon circulates through the ocean, and approximately 50% of carbon trapped in ocean sediment is in coastal habitats [2, 3]. That is a significant contribution considering that blue carbon ecosystems cover less than 0.5% of the ocean floor. By protecting and restoring coastal habitats, we can ensure that blue carbon continues to work for us in mitigating carbon dioxide's effects on climate change.

Blue carbon represents a no lose situation for the environment. We provide more services to our environment than carbon sequestration by protecting and restoring coastal habitats. 

Eelgrass sequesters carbon

Blue carbon ecosystems include mangrove forests, tidal marshes, and seagrass meadows. Seagrass is a powerful source of blue carbon; it accounts for 10-18% of the total carbon burial in the ocean and accounts for approximately 0.1% of the coastal ocean [4].

Eelgrass has an enhanced capacity to sequester carbon in the soil sediments due to its three-pronged approach.

  1. Photosynthesis traps carbon; the plants accumulate carbon in the meadows. As the roots and rhizomes grow, they retain carbon in the sediments [5, 6]. The roots and rhizomes have a prolonged decomposition time, contributing to the long-term carbon retention by eelgrass.

  2. Eelgrass is an efficient filtration system; it draws carbon-rich particles out of the water column and settles them into the sediments in the meadows [7, 8].

  3. Eelgrass limits the resuspension of particles by dissipating waves and turbulence [9]. Without high current speeds, the sediment will retain the carbon for longer periods.

Eelgrass Destruction Releases Carbon

Human negligence has lost 1.5% of global seagrass every year since the 1940s [10]. Even tropical forests lose less ground annually [11]. Seagrass loss has many sources:

  • Physical damage - propellers, anchors, mooring chains, dredging, and destructive fishing practices can all rip up eelgrass and fragment the habitat [12, 13]

  • Pollution - nitrogen from fertilizers and sewage leakage cause an imbalance in nutrient ratios within eelgrass [14]. Pollution also causes damage through indirect causes [15].

  • Rising water temperatures - eelgrass thrives in cool water conditions and is susceptible to wasting disease in higher temperatures [16, 17].

  • Invasive species - European green crabs rip up eelgrass when foraging and sheltering [18, 19].

  • Sea level rise and decreased water clarity - deeper waters and turbid waters restrict the light available to eelgrass [20].

Destroying eelgrass beds will lead to the release of the blue carbon the meadows stored [21]. Carbon resuspends without the seagrass beds holding it down, meaning that the former eelgrass habitat becomes a carbon source.

Eelgrass Works for You!

Unlike technological carbon solutions, eelgrass provides additional environmental ecosystem services.

  • Recreation - bird watching, scuba diving, snorkeling, and recreational fishing all benefit from the habitat that eelgrass provides

  • Fisheries Enhancement - coastal fish feed off and in blue carbon ecosystems. These ecosystems account for 61% of the diet of commercially fished nearshore fish [22].

    • Seagrass has globally contributed $20.35 million to commercial fishery enhancement.

  • Coastal Protection - eelgrass reduces the power of waves and water currents; seagrass provides $53.43 million in avoided damage.

Without Eelgrass…

Eelgrass brings carbon out of the water column, traps carbon in the soil, and retains carbon in its roots and rhizomes. It also contributes to fishery enhancement and helps coastal properties weather the effects of erosion.

When we destroy eelgrass, it becomes a source of carbon. It will add to our greenhouse gas emissions crisis, and our climate will suffer. Furthermore, the blue carbon system we take advantage of would no longer be operational. Seagrass plays a crucial role as one of the three main coastal blue carbon generators. The long-term consequences of this loss are difficult to count.

Beyond the blue carbon service, eelgrass protects our coastlines from erosion and destructive weather events. Fishermen, boaters, and all recreational beach users will feel the lasting effects of eelgrass loss. Our oceans will become less lively as critical habitat is lost. Snorkelers, birders, fishers, and divers will not have beautiful underwater communities to enjoy.

There are no social or ecological harms when we protect and expand eelgrass habitat. We all benefit from its hard work and should do better to protect it.