What is the primary difference between a swamp and a marsh?

The primary difference lies in the dominant vegetation: swamps are dominated by woody plants like trees and shrubs, whereas marshes are dominated by herbaceous plants like grasses and reeds.

How do mangroves differ from salt marshes in terms of geographic distribution?

Mangroves are temperature-dependent and restricted to tropical and subtropical latitudes (roughly $30^\circ$ N to $30^\circ$ S), while salt marshes are found globally and are not strictly limited by temperature.

Compare the carbon sequestration rates of salt marshes and terrestrial forests.

Salt marshes are significantly more efficient at sequestering carbon, often storing it at a rate up to 50 times greater than that of terrestrial forests due to their anaerobic soil conditions which slow decomposition.

What is a common misconception regarding the water source of bogs?

A common misconception is that bogs are fed by groundwater or runoff; in reality, bogs are primarily fed by precipitation, which contributes to their characteristic acidic and nutrient-poor environment.

Why is 'filling' a wetland for development considered more damaging than temporary flooding?

Filling involves adding soil or rocks to raise the land level, which permanently destroys the hydric soil and vegetation, whereas flooding is a natural process that the ecosystem is adapted to handle.

What error do students often make when describing the impact of dams on wetlands?

Students often focus only on the loss of water, but dams also trap essential sediments; without this sediment replenishment, coastal wetlands cannot maintain their elevation against rising sea levels.

Define the 'intertidal zone' in the context of mangrove growth.

The intertidal zone is the area of the shoreline that is exposed to the air at low tide and submerged in water at high tide, creating the specific environmental conditions mangroves are adapted to.

What are 'keystone species' in a wetland ecosystem?

Keystone species are organisms that have a disproportionately large effect on their environment relative to their abundance; in wetlands, certain fish or birds maintain the balance of the food web.

What is eutrophication?

Eutrophication is the process where a body of water becomes overly enriched with minerals and nutrients (often from runoff), inducing excessive growth of algae and resulting in oxygen depletion.

How do wetlands contribute to water purification?

They slow down water flow, allowing suspended sediments to settle, and the plants and microbes within the wetland absorb and neutralize pollutants like nitrogen, phosphorus, and pesticides.

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Environmental Science

Unit 8: Aquatic & Terrestrial Pollution

Human Activities on Wetlands & Mangroves

Summary

Wetlands and mangroves are critical transition ecosystems that provide essential services like water filtration, flood mitigation, and carbon sequestration. However, they are increasingly threatened by human activities such as commercial development, dam construction, and unsustainable aquaculture, which disrupt their delicate hydrological and biological balances.

1. Definition & Core Concepts

Wetlands are diverse ecosystems characterized by land that is submerged in water either permanently or seasonally, acting as a transition zone between terrestrial and aquatic environments.
Mangroves are specialized woody plants that thrive in the intertidal zones of tropical and subtropical coastlines, typically located between $30^\circ$ N and $30^\circ$ S of the equator.
Salt Marshes are coastal wetlands that, unlike mangroves, are not strictly temperature-dependent and are characterized by flat terrain with numerous drainage channels.
The salinity of these environments varies significantly, ranging from freshwater to brackish and hypersaline, requiring specialized adaptations for the flora and fauna residing there.

Diagram showing a coastal wetland profile with mangrove trees in the intertidal zone, illustrating the relationship between the water table and submerged land.

2. Classification of Wetland Systems

Inland (Non-Tidal) Wetlands

Swamps: Dominated by woody plants like trees and shrubs, these areas often feature stagnant water with low dissolved oxygen levels due to slow decomposition.
Marshes: Primarily composed of herbaceous plants such as grasses and reeds, providing shallow water habitats for diverse wildlife.
Bogs: Acidic wetlands that rely on precipitation rather than runoff, characterized by the accumulation of peat moss and specialized nutrient-poor soil conditions.

Coastal (Tidal) Wetlands

These include estuaries and lagoons where freshwater from rivers meets the saltwater of the ocean, creating a high-stress environment due to fluctuating salinity.

3. Ecosystem Services & Value

4. Anthropogenic Threats & Impacts

5. Key Distinctions

6. Exam Strategy & Tips