After switching universities, I joined a lab at SUNY ESF in Syracuse, New York that performs research in wetland ecosystems. Specifically, the way wetlands harness carbon from the atmosphere while exhaling methane. It's quite the switch from my previous work focusing on ticks and vector-borne diseases, but I am excited to focus on a topic that deals directly with greenhouse gases and climate change. I probably know just as much about wetlands as the general public, and, after jumping back into the literature, I've rediscovered how cool and important wetlands are.
First thing's first: what is a wetland?
Wetlands are areas of land that are covered with water at least part of the year, and they are very variable in how deep the water gets, what kinds of plants grow, how acidic the water is, where they are located (by the shore or inland), and if the water is freshwater or saltwater. Some of the many types of wetlands include: bogs, fens, swamps, marshes, and peatlands.
Wetlands can get a bad rep and be named things like "The Great Dismal Swamp" and have humans decide to drain them (ahem, George Washington), but that's only because some people fail to see and understand the beauty and importance of these ecosystems.
The Magic of Wetlands
Wetlands bring a lot to the table when it comes to environmental and human health. They:
Improve water quality
Support wildlife
Mitigate floods
Protect the coast
Sequester carbon
Improve Water Quality
Wetlands are such impressive filters that people have started constructing them as a means to improve water quality in man-made systems. When water bodies are inundated with nutrients like nitrogen and phosphorus (from agricultural runoff, septic systems, animal manure, etc.), eutrophication can occur which causes an overgrowth of plants and algae (termed algal blooms) that strip the water of oxygen leading to dead zones (areas void of life). Furthermore, algal blooms can be toxic to human health and decrease recreational opportunities. Luckily, plants in wetlands absorb these nutrients. But, how much can wetlands absorb? When an excess of nutrients enters the water, they flow into natural areas where the water collects, called catchments. Wetlands don't even have to take up a lot of space to have incredible effects: if 2-7% of a catchment is made up of wetlands, nitrogen can be reduced by 20-50% (1)! Wetlands also trap sediments and can help detoxify chemicals through biological processes (2). Basically, wetlands are Mother Earth’s liver and kidneys, and you need to protect them.
Support Wildlife
Wetlands are booming zones of biodiversity. The copious amounts of food and high levels of primary productivity (y’know, the base of the food chain that supports the rest of life) powers thousands of species, permitting wetlands to be among the most productive ecosystems in the world. These systems are home to a myriad of plants, microorganisms, amphibians, reptiles, insects, birds, fish, and numerous other vertebrates and invertebrates, all of which are intertwined within complex food webs. These pockets of land are biodiverse sanctuaries, providing a place to migrate to, breed, and grow. When the size of wetlands declines due to anthropogenic activities, there is a decrease in species richness and often abundance (3), which can have a direct impact on the food chain. In short, wetlands are crucial for biodiversity, and restoration, conservation, and maintenance efforts should be made to ensure the longevity of this ecosystem service (4).
Mitigate Floods
The presence of wetlands allows a buffer against flood events which can preserve the integrity of cities and homes. Instead of having massive amounts of water inundate the land, wetlands act as a sponge, and trees and other vegetation help trap the water in their roots, slowly releasing it over time. Along the Mississippi River, bottomland hardwood wetlands once held floodwater for 2 months, but, due to human's draining and filling the wetland, now they hold water for less than two weeks (5).
Protect the Coast
Wetland vegetation provides a physical buffer against the constant beating of waves by slowing down the velocity of water and firmly holding onto the sediment, reducing erosion. One type of wetland that is essential for doing this is the mangrove wetland. Mangroves stabilize the coastline with their extensive root system while reducing the impact of waves, shown in a great model here. In Florida, they "prevented $1.5 billion in direct flood damages and protected over half a million people during Hurricane Irma in 2017"(6).
Sequester Carbon
The cool thing about wetlands is that they can also help mitigate the climate crisis by absorbing insane amounts of carbon dioxide (CO2), a greenhouse gas that traps heat in the atmosphere. Though wetlands don't take up much space globally (about 5-8% of land), they hold 20-30% of the world's soil carbon (7). When these wetlands are destroyed, the CO2 goes into the atmosphere. Peatlands make up half of all wetlands, and they store twice as much carbon as forests (8). This type of wetland is constantly water-logged which slows down the process of decomposition, creating a buildup of decaying and dead matter that forms peat soil. When peatlands are drained and/or catch on fire, all the carbon returns to the atmosphere, and this is 5% of human-caused CO2 emissions (9). So, don’t do that.
The loss of wetlands
Wetlands are highly threatened and are disappearing at a rapid rate: 64-71% of all wetlands have been lost since the 1900s (10). The loss of wetlands is due to climate change, pollution, drainage, invasive species, and exploitation of natural resources (11). As wetlands become drained or filled, you can expect that 1) water quality and availability would decline affecting human and animal health, 2) biodiversity would reduce, 3) recreational activities would be lost, 4) coastlines would erode, 5) flooding would cause billions of dollars in damage and repair to cities and communities, and 6) immense amounts of CO2 would release into the atmosphere, contributing to climate change.
Efforts should be made to restore, maintain, and protect wetlands. There are ways to become active stewards which you can read more about here. Discover if there are wetlands near you (check out the Wetland Mapper!) and how to get involved with restoration or environmental monitoring projects. Also, reach out to your elected officials about protecting these critically important ecosystems!
References:
1. Verhoeven, J.T.A.; Arheimer, B.; Yin, C.; Hefting, M.M. Regional and global concerns over wetlands and water quality. Trends Ecol. Evol. 2006, 21, 96–103, doi:10.1016/J.TREE.2005.11.015.
2. Wetland Functions and Values: Surface and Ground Water Protection | Department of Environmental Conservation. Available online: https://dec.vermont.gov/watershed/wetlands/functions/water-quality (accessed on Jun 13, 2022).
3. Houlahan, J.E.; Findlay, C.S. The effects of adjacent land use on wetland amphibian species richness and community composition. https://doi.org/10.1139/f03-095. 2011, 60, 1078–1094, doi:10.1139/F03-095.
4. Dertien, J.S.; Self, S.; Ross, B.E.; Barrett, K.; Baldwin, R.F. The relationship between biodiversity and wetland cover varies across regions of the conterminous United States. PLoS One. 2020, 15, e0232052, doi:10.1371/JOURNAL.PONE.0232052.
5. Why are wetlands important? | US EPA. Available online: https://www.epa.gov/wetlands/why-are-wetlands-important (accessed on Jun 13, 2022).
6. The importance of mangroves in Florida. Available online: https://www.nature.org/en-us/about-us/where-we-work/united-states/florida/stories-in-florida/why-mangroves-important/ (accessed on Jun 13, 2022).
7. Mitsch, W.J.; Gosselink, J.G. Wetlands; 4th ed.; Wiley, 2007;
8. Peatlands store twice as much carbon as all the world’s forests Available online: https://www.unep.org/news-and-stories/story/peatlands-store-twice-much-carbon-all-worlds-forests (accessed on Jun 13, 2022).
9. Peatlands and climate change | IUCN. Available online: https://www.iucn.org/resources/issues-briefs/peatlands-and-climate-change (accessed on Jun 13, 2022).
10. Davidson, N.C. How much wetland has the world lost? Long-term and recent trends in global wetland area., doi:10.1071/MF14173.
11. World Wetlands Day | United Nations. Available online: https://www.un.org/en/observances/world-wetlands-day (accessed on Jun 13, 2022).
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