Why does draining a swamp or clearing a mangrove cost us far more than the land we gain?
Topic 8.4 Human Impacts on Wetlands and Mangroves: describe the ecosystem services of wetlands and mangroves and the consequences of destroying them.
A focused answer to APES Topic 8.4, covering the ecosystem services of wetlands and mangroves (flood control, water filtration, nursery habitat, carbon and coastal protection), the human causes of their loss, the consequences, and restoration, with a worked flood-storage calculation.
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What this topic is asking
The College Board (Topic 8.4) wants you to describe the ecosystem services of wetlands and mangroves and the consequences of destroying them.
Ecosystem services of wetlands and mangroves
Human causes of loss
Consequences and restoration
Why this matters
This topic makes the abstract idea of ecosystem services (Unit 2) concrete and ties it to pollution and coastal risk. It connects to eutrophication (wetlands filter nutrients), to aquatic biomes (Unit 1), and to climate (mangroves store carbon and buffer the sea-level and storm impacts of Unit 9).
Try this
Q1. Identify two ecosystem services provided by wetlands. [1 point]
- Cue. Any two of flood control, water filtration, groundwater recharge, fish nursery habitat, biodiversity, carbon storage.
Q2. Explain how mangroves protect coastlines from storms. [2 points]
- Cue. Mangrove roots absorb wave and storm-surge energy and trap sediment, so they buffer the shore against storm damage and erosion, reducing the impact of storms on the coast behind them.
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2022 (style)4 marksSection II (FRQ). (a) Identify two ecosystem services provided by wetlands. (b) Explain how mangroves protect coastlines. (c) Identify one human activity that destroys wetlands or mangroves. (d) Describe one consequence of losing these ecosystems.Show worked answer →
A 4-point FRQ on wetlands and mangroves.
(a) Identify (1 point): any two of flood control, water filtration, groundwater recharge, nursery habitat for fish, biodiversity, or carbon storage.
(b) Explain (1 point): mangrove roots absorb wave energy and trap sediment, buffering the coast against storm surge and erosion.
(c) Identify (1 point): draining for agriculture or development, dredging, pollution, or clearing for shrimp farms or coastal building.
(d) Describe (1 point): increased flooding and storm damage, loss of fish nurseries and fisheries, reduced water quality, and loss of stored carbon.
Markers reward two valid wetland services, the wave-buffering and sediment-trapping role of mangroves, a valid destructive activity, and a valid consequence of loss.
AP 2018 (style)1 marksSection I (multiple choice). One important ecosystem service provided by coastal wetlands and mangroves is that they: (A) increase the speed of storm surge reaching the shore (B) buffer coastlines from storms and filter pollutants (C) raise local water temperatures (D) prevent fish from breeding. Justify your choice.Show worked answer →
A 1-point MCQ on wetlands and mangroves. The answer is (B).
Wetlands and mangroves buffer coastlines by absorbing wave and storm-surge energy, and they filter pollutants and sediment from water, among other services. They reduce, not increase, storm surge (A), do not raise water temperature (C), and provide nurseries that help fish breed, not prevent it (D). The trap is overlooking the many valuable services these ecosystems provide, which is why their loss is so costly.
Related dot points
- Topic 8.2 Human Impacts on Ecosystems: explain how pollution and other human activities disrupt ecosystems and harm organisms.
A focused answer to APES Topic 8.2, covering how pollution, oil spills, plastic, heavy metals and habitat disturbance disrupt ecosystems, the idea of ecological tolerance and indirect effects through food webs, coral reef damage, and ecosystem recovery, with a worked species-loss reasoning example.
- Topic 2.2 Ecosystem Services: describe the four categories of ecosystem services and explain how the disruption of ecosystems affects the services they provide.
A focused answer to APES Topic 2.2, covering provisioning, regulating, cultural and supporting ecosystem services, examples of each, their economic value, and how disruption reduces them, with a worked valuation question.
- Topic 8.5 Eutrophication: explain how nutrient pollution causes eutrophication and oxygen depletion in aquatic ecosystems.
A focused answer to APES Topic 8.5, covering how nitrogen and phosphorus runoff causes eutrophication, the algal bloom and decomposition sequence, hypoxia and dead zones, cultural versus natural eutrophication, and how to prevent it, with a worked dissolved oxygen reasoning example.
- Topic 1.3 Aquatic Biomes: describe the major freshwater and marine biomes and explain how abiotic factors such as salinity, depth, light, temperature and nutrients shape them.
A focused answer to APES Topic 1.3, covering freshwater and marine biomes, salinity, the photic and aphotic zones, estuaries, coral reefs and wetlands, and the abiotic factors that control aquatic productivity, with a worked dissolved-oxygen question.
- Topic 8.1 Sources of Pollution: distinguish point and non-point sources of pollution and identify major types of pollutants.
A focused answer to APES Topic 8.1, covering the distinction between point and non-point sources of pollution, examples of each, why non-point sources are harder to control, the major pollutant types, and how this shapes management, with a worked load calculation.
Sources & how we know this
- AP Environmental Science Course and Exam Description — College Board (2020)