Breath of Clarity

Comment #2: Mangrove and Freshwater Swamps

Original Post by Samantha Krieger:

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?

One of the major factors in oxidizing sediments in mangrove swamps is the processes and actions of the various crab species that call mangroves home. The influence crabs have across mangrove ecosystems puts them in the position of the keystone species of the ecosystem, with their presence altering carbon cycling, biodiversity, sediment microtopography, and soil chemistry (Mitsch and Gosselink 2015, 326). Crabs burrow in the sediments of mangrove habitats, which oxygenates the soil, lessening concentrations of sulfide, ammonium, and salt in mangrove soils by allowing the water and oxygen to better penetrate the soil (Mitsch and Gosselink 2015, 326-327).

The other major factor playing a role in the oxidizing of Mangrove swamp soils are the impacts of the tides. “The physical flushing by tides is important for the mangrove oxygen supply” (Bhutani 2006). The openness of the wetland soil to freshwater tidal flows moves soil and increases the oxygen content, which, alongside the physical root adaptations to take in oxygen from the air and transfer that directly into the sediment, increases the oxidation of the soil (Bhutani 2006; Mitsch and Gosselink 2015, 325).

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

Mangroves are an important source of habitat for a variety of organisms. The complex underwater prop root complex and tidal channels, the forest floor, and the canopy provide habitat for a large number of aquatic, terrestrial, and bird species (NHMI n.d.). Commercial and recreational fisheries depend upon mangroves for healthy tropical fish populations and consistent stock replenishment, providing both food for organisms in their early life stages and protection for predators for juveniles (Mitsch and Gosselink 2015, 333). Mangroves are critical habitat for several endangered and threatened species, as well as some overexploited species with economic value (NHMI n.d; Blum 2017).

In addition to the economic damage that would take place with massive mangrove ecosystem loss, there would be environmental impacts on other ecosystems as well. With the loss of mangrove ecosystems as nursery habitat, there would be a loss/decline in the numbers of adult fish populations venturing out of nursery habitats and into the ocean or adjoining reefs, which would have a negative impact on aquatic keystone species that depend on these fish as prey. Mangrove loss would also result in less natural absorption of the shock of hurricanes, resulting in damage to and the loss of terrestrial habitat along the shoreline and further inland, as well as the loss of vast amounts of natural carbon storage which would harm every ecosystem.

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

Inland freshwater marshes, especially throughout the Midwest, are often largely impacted by agricultural activity, including pollution from chemical and natural wastes. The absorbing properties of wetlands make it possible for them to be used as a natural form of filtration of harsh agricultural chemicals such as nitrogen and phosphorus and other waste elements from surface runoff before it moves further down the riverine system and damages oceanic ecosystems or drinking water sources (EPA n.d.). Freshwater marshes are now becoming known for their natural filtration ecosystem services, leading to their restoration throughout the Midwest. Living and roaming throughout the Mississippi River Basin and the Illinois River Basin region for many years, I had heard of the efforts of various groups -such as Ducks Unlimited and The Nature Conservancy on the NGO side, and the Illinois Department of Natural Resources and Monsanto on the governmental and corporate side,- to incentivize farmers to add strips of riparian buffer, often wetland but location-dependent, to the 150 feet or so of their land that bordered waterways.

While in places like the Illinois River Basin, the wetland ecosystem may have been resilient enough to at one time handle the runoff from small-scale family farms, the impact of corporate industrial agriculture results in much greater levels of degradation. Contaminated water can stand in freshwater marshes, allowing the uptake of nutrients, however, when overloaded by larger amounts of industrial agriculture these freshwater marshes can leak nutrients into vital waterways. While the restoration of more wetland areas would lessen the impact of agriculture while increasing biodiversity across the Midwest’s natural ecosystems, a serious look needs to be taken at Western agricultural practices and the environmental impact they have. While the restoration of wetland ecosystems is valuable due to their vital ecosystem services, without changes in production, there is still the growing possibility of these services being overwhelmed as we try to feed a growing population.

Please post your power point as an attachment in this week’s discussion board. Make at least one of your responses to be on one of your fellow student’s power point. But you can respond to as many as you like. It will be a great learning experience.

Please see the attachment.


Bhutani, Puja K. 2006. ”Mangrove Swamps.” PowerPoint for Wetland Ecology and Management, August 11, 2006.

Blum, Juliet. 2017. “Mangroves: nurseries for the world’s seafood supply.” IUCN, August 24, 2017. (Links to an external site.)

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

Mitsch, William J. and James G. Gosselink. 2015. Wetlands. 5th ed: John Wiley and Sons, Inc

NHMI. N.d. “Mangroves.”

My Comment:

Hi Samantha (Question 3),

Thanks for all the info about wetlands in the Midwest. I am originally from Chicago. Also, excellent depiction of how surface runoff moves further down the riverine system. In aquatic ecosystems, over-enrichment with phosphorous and nitrogen causes a wide range of problems, including toxic algal blooms, loss of seagrass beds. degradation of coral reefs, and loss of biodiversity. I would emphasize to the farmer over-enrichment seriously degrades resources which impairs use for further farming purposes.