8.4 Human Impacts on Wetlands and Mangroves

Wetlands and Mangroves are very important aquatic ecosystems. They provide several environmental services to humans, plants, and animals. But they are also threatened like many other habitats. 

There is one learning objective the College Board wants us to learn:

• STB-3.E: Describe the impacts of human activity on wetlands and mangroves.

What are Wetlands?

Image from Elly Kedlers via Unsplash

Wetland: according to the EPA, Wetlands are areas where water covers the soil either part or all of the time

The EPA also groups wetlands into two distinct groups:

Coastal/Tidal Wetlands

• These are usually related to estuaries (an area where water from the sea meets and mixes into freshwater).
• The differences in salinity make it difficult for plants to grow.- An exception would be mangroves. Mangrove trees have adapted to the high salinity levels of estuaries.- Mangroves: According to the NOAA, Mangroves are a group of trees and shrubs that live in the coastal intertidal zone.

Inland/Non-tidal Wetlands

• Usually near rivers, streams, lakes, and ponds.
• Examples of inland wetlands include swamps and marshes.
  

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Learn more about:  1.3 Aquatic Biomes 🐠

Importance of Wetlands 

1. Water Purification
   • Wetlands filter runoff, such as agricultural pesticides, before it reaches larger bodies of water. Plants use the nutrients wetlands trap.
   • Wetlands also actively trap greenhouse gases, which reduces the strain on the atmosphere.
2. Flood Protection
   • Wetlands are meant to hold water, so when huge amounts of water runoff, the wetlands can absorb all of it.
   • When we alter wetlands by filling them up, we reduce their ability to reduce the effects of a torrential downpour.
3. Habitat
   • Many animals call wetlands home. Amphibians like frogs and salamanders live in wetlands because they can live in wet environments. Certain fish and bird species also find it hospitable since there are varied food sources.

Why Wetlands are Disappearing

1. Commercial Development

• Companies often try to fill wetlands up to build houses and big commercial malls and arenas, destroying the habitat for all the animals in the wetlands.

• Filling wetlands also reduces its ability to prevent floods. Unfortunately, homes built on these covered wetlands are more susceptible to these floods if the wetlands can not control them through absorption. 2. Dam Construction

• The primary purpose of dams is to divert water flow. Sometimes the water is used to power electricity or is stemmed to allow easier commercial development.

• Dams prevent water from actually reaching the wetlands. Since they cannot refill, it is impossible to maintain their reservoirs, and they become drained. Many animals cannot live there anymore. It also does not purify the water that humans need to keep costs low for drinking water.

  

Image from Daniel Morris via Unsplash

3. Overfishing

1. Fish in wetlands are important predators and prey in the wetland ecosystem. They are keystone species - without them, the ecosystem would greatly suffer. The low fish population might lead to a massive reduction in species that rely on them for survival. Biodiversity is the most important to an area, and overfishing significantly threatens that. 4. Pollutant Runoff

2. Wetlands are very vulnerable to chemical pollutants since runoff usually ends up in bodies of water. These pollutants are meant to be disposed of and should not end up in water bodies.

3. However, many of them still do, which affects the ability of fish to breathe since they are not used to filtering such contaminants.

4. Some can even cause an overgrowth of nutrients in wetlands. This is known as cultural eutrophication.

   • Plants like algae would grow due to the excess nutrients and would disrupt the natural order of things. It would cause a decline in some species and increase others, which could completely collapse the ecosystem.

Learn more about: 8.2 Human Impacts on Ecosystems

Recap

The most important thing about wetlands is that they are CRUCIAL to our biosphere. They provide many services such as water filtration, habitation for animals, and even flooding controls. 

Unfortunately, they are under attack because of human-induced activities. But we can help save them by being aware of developments that could threaten our local wetlands.