Breath of Clarity

Mangroves and Freshwater Swamps

There are two major factors oxidizing sediments in a Mangrove swamp. One is an animal and one is not. What are they and how do they change the chemistry of the sediment?

The two major factors oxidizing sediments in a Mangrove swamps are crabs and storms. Crabs dig into the sediment of mangrove swamps. As they do so, they eat plant material that is decomposing as well as some mangrove seedlings (Mitsch and Gosselink, 2015). As they break up the soil, they create space which enables oxygen to seep through and enter the soil. From there, built up sulfide and ammonium is released (Mitsch and Gosselink, 2015).

Storms result in the same effect of oxygenating the mangrove swamp (Mitsch and Gosselink, 2015). However, it happens through a distinctly powerful physical force. Storms also move the soil around which results in oxygen passing into the sediment (Mitsch and Gosselink, 2015). Considering that storms go hand in hand with sea level rise, the increased amount of salt water entering the soil is conducive to mangrove tree growth (Mitsch and Gosselink, 2015). As a result, mangrove trees gain the upper hand in competition with other vegetation that is not as salt tolerant (Mitsch and Gosselink, 2015). The mangrove trees tend to trap, hold and stabilize intertidal sediments (NHMI, n.d.). Black mangroves may be the best land stabilizer due to easier seedling transport, quick aerial root production, underground root systems increase sediment holding capabilities, higher tolerance to cold temperatures, and better ability to inhabit dredge and fill sites (NHMI, n.d.). During storms and hurricanes mangrove forests protect landward coastal area by mitigating damage from waves, currents, and winds (NHMI, n.d.).

How do mangrove swamps function as nurseries? How would destruction of mangrove environments affect other ecosystems?

A variety of organisms utilize mangrove habitats as they are inhabitants of the underwater prop root complex and tidal channels (NHMI, n.d.). The peat is the start of the food chain. The bacteria breaks down, essentially decomposing material to generate energy. Then, it is consumed by phytoplankton and algae. From there, a range of invertebrates and eventually fish participate in the food chain. A plethora of fish and shellfish caught commercially and by recreational means utilize mangrove habitat at some point in their life cycle (NHMI, n.d.). The fish are able to hide in the root complex to reduce their exposure to predators at a young age before exploring the ocean. In addition to the marine organisms, both terrestrial organisms and birds utilize the forest floor, root complex and the canopy (NHMI, n.d.). Mangrove communities are also known to provide habitat for number of threatened and endangered species. Among the endangered species in Florida mangroves are the American Crocodile, Hawksbill and Atlantic Ridley Turtles, Bald Eagle, American Peregrine Falcon, Key Deer, Barbados Yellow Warbler, Atlantic Saltmarsh Snake. Threatened species are the American Alligator, Green and Loggerhead Turtles (NHMI, n.d.). Clearly, the mangrove swamps serve as a crucial type of nursery.

The video below illustrates how mangrove environments are connected to many other ecosystems:

According to the video, one way that destruction of mangrove environments would affect other ecosystems is related to its impact on the ocean. Mangrove swamps help to keep the ocean clean. Their tangled root system filters dirty water as it flows into the sea.

Mangroves also act as a natural carbon storage mechanism more so than traditional, terrestrial forests. The tangled network of roots in mangroves traps the carbon material in the water-logged soil, sealing it off from the atmosphere. The vault can remain secure for a millennia as long as the mangrove forests are in tact. In Gazi Bay, Kenya the mangrove forest stores 1,500 tons/hectare of carbon. However, barely half the world’s original mangroves remain. Destruction of mangroves affect all other ecosystems that are degraded by climate change as they help to mitigate global warming.

Mangroves are essential in protecting shorelines from damaging storm and hurricane winds, waves, and floods. They’re able to slow tidal motion, which in theory would help prevent extreme damage from storm surges (National Ocean Service, n.d.). With the sea level rising, flooding will become a more prominent and frequent concern for coastal communities, and any assistance they can get in minimizing the impact is crucial.

Why are freshwater marshes used to clean up water and effluent from corporate pig farm operations in the USA?

The freshwater marshes are used to clean up water and effluent from corporate pig farm operations because they are productively able to absorb excess nutrients. Highly organic, mineral rich soils of sand, silt, and clay underlie these wetlands (Environmental Protection Agency n.d.). Specifically, the freshwater marshes can filter excess nutrients from surface runoff due to the vegetation that thrive in freshwater marsh conditions (Environmental Protection Agency n.d.). The freshwater marsh would be able to pick up the excess nitrogen and phosphorous from the pig manure that is part of the farm’s runoff.

Marshes can also slow the rate that water enters rivers and streams as runoff (Mitsch and Gosselink, 2015). The water will remain in marshes as standing water for an extended period of time, allowing more nutrients to be pulled from the water (Mitsch and Gosselink, 2015). However, when marshes become oversaturated with nutrients, however, they can leak nutrients out if overwhelmed (Mitsch and Gosselink, 2015). To combat it, managers can plant additional vegetation that is are particularly suited for cleaning up the water. Grasses (wheatgrass and clover), shrubs (rabbit brush and sagebrush) and trees (willow and hybrid poplar) have been used extensively as barriers between runoff sources and estuaries (New Jersey Department of Environmental Protection 2014). The majority of these barriers are built with common reeds (Stefanakis and Tsihrintzis 2014). Other interesting ones include Phalaris sp., Scirpussp., Typha angustifolia, Typha latifolia, Solidago rigida, Rumex crispus, Cirsium vulgare, Urtica dioica, Salix spp., Cannabis sativa, and Carex acutiformis (Stefanakis and Tsihrintzis 2014). Planting vegetation is definitely a strategy to combat the issue of some farmers being unwilling to change their ways.

Reference List:

Environmental Protection Agency. n.d. “Classification and Types of Wetlands”.

National Ocean Service. n.d. “What is a ‘mangrove’ forest.” Accessed November 10, 2020.

New Jersey Department of Environmental Protection. 2014. “Technical Guidance on the Capping of Sites Undergoing Remediation”. Accessed November 10 2020.

Mitsch, William J., and James G. Gosselink. 2015. Wetlands. John Wiley & Sons, Inc.

Stefanakis, Alexandros and Vassilios Tsihrintzis. 2014. “Landfill Leachate Effluents”. Science Direct.

Comment by Jenny Kelley:

Hi Mary –

I enjoyed your presentation for class. I knew very little about mountain bogs and found the comparison with abandoned cranberry bogs in New Jersey fascinating. The article provided pertinent evidence for the folks trying to restore the North Carolina cranberry bogs/mountain bog even though little is known about the rare ecosystem, as you mentioned. I also found it very interesting that cranberries grew in North Carolina and were threatened. I saw on your map that your area was near Boon, NC. That is a popular spot along.around the Blue Ridge Parkway, hopefully the nonprofit you mentioned can glean more support for their efforts from visitors and residents alike, especially with the evidence from New Jersey that indeed, with proper maintenance (like permanent flooding), the area can be restored. Also, the mountain bog, and its service -as many other wetlands provide – of regulating water and absorbing floodwaters, would also be a key reason for the state to support restoration initiatives I hope.

Your presentation was of such a unique and rare natural community. I am so glad to know more about this part of the world and such an interesting wetland! Great work!!!


My Reply:

Hi Jenny,

Thanks so much for taking a look at the powerpoint! I also found it so interesting that cranberries are a threatened species in North Carolina. I received the information about the species within a one-mile radius of the bog from a contact I emailed from Foothills Conservancy. It was helpful to understand the context and see how close it is to Pisgah and the Blue Ridge Parkway. I find it fascinating to connect the definition of a bog with the management practice (permanent flooding) that restores it. It would be interesting to show this sort of powerpoint presentation to people that are considering making a donation.

Comment by Hannah Claycomb:

Mary, awesome post! In regards to question 2:

I appreciated how you explained the functionality of mangroves as nurseries by providing information about the entire food chain. Mangroves house so many species and provide security for them as well. It is amazing to learn how primary producers (like mangrove trees & vegetation) heavily assist in providing food and shelter for the many animals that call mangroves home. Vegetation is a crucial component to wetlands and pretty much determines chemical and biological outcomes in that wetland; to support this, you provided ample information about how vegetation alone can mitigate runoff pollution from pig farms in the following question. Loved your examples of the ways wetland managers can implement certain forms of vegetation to control pollution/nutrient uptake. I also was not aware at the amount of mangrove species that are threatened/endangered, so thanks for supplying that information. Great post!

Comment by Professor Flanagan:

Hi Hannah, Mary, and Jenny,

In regards to Q2 – That was an interesting video, Mary. Thanks for posting. Another benefit of mangroves is they filter sediment leaving the ocean cleaner and this protects the offshore coral reefs from being choked to death.