Wetlands are areas where water covers the soil at least part of the year (CED EK STB-3.E.1)—think marshes, swamps, bogs, peatlands, and mangrove forests. That seasonal soil saturation makes them different from “regular” open water bodies (like lakes or rivers): wetlands have soils high in organic matter and plants adapted to low-oxygen soils (hydrophytes), so they store lots of carbon (blue carbon) and build peat. Functionally, wetlands act as natural water filters, removing sediments and pollutants, buffer storm surge and flooding, and serve as nursery habitat for many species (CED EK STB-3.E.2). They’re also vulnerable to human threats like coastal development, dredging, dam construction, overfishing, and agricultural/industrial pollutants (CED EK STB-3.E.3). For AP prep, review Topic 8.4 in the Fiveable study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and practice related problems (https://library.fiveable.me/practice/ap-environmental-science).

Wetlands matter because they do a lot of heavy lifting for ecosystems and people. By definition, wetlands have water covering the soil some or all of the year (EK STB-3.E.1). They provide key ecosystem services: water purification and filtration (removing nutrients and pollutants), flood and storm-surge attenuation (storing excess water), nursery habitat for fish and wildlife, and long-term carbon storage in peat and “blue carbon” ecosystems (EK STB-3.E.2). Losing them from coastal development, damming, dredging, overfishing, agricultural runoff (eutrophication), sedimentation, or saltwater intrusion reduces those services and raises flood risk and water-quality problems (EK STB-3.E.3). For AP review, focus on services, threats, and restoration/mitigation tools like buffer zones and mitigation banking—these are commonly tested in Topic 8.4 (STB-3.E). For a concise study guide, check Fiveable’s Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and more unit practice at (https://library.fiveable.me/ap-environmental-science/unit-8).

Wetlands (including mangroves) provide a bunch of high-value ecosystem services you should memorize for the exam: water purification/filtration (they trap sediments and remove nutrients and pollutants), flood and storm-surge protection (mangroves attenuate waves and wetlands store excess water), important habitat and nursery grounds for fish and birds (boosting biodiversity and fisheries), carbon sequestration or “blue carbon” storage (peatlands and mangrove soils lock carbon for long periods), and groundwater recharge/buffer zones that reduce erosion and saltwater intrusion. These are all listed in the CED (EK STB-3.E.2) and are common AP-style short-answer/multiple-choice topics, so link the service to human threats (development, dredging, pollution, dams, overfishing) when you explain impacts. For a quick review, see the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) or the Unit 8 overview (https://library.fiveable.me/ap-environmental-science/unit-8). More practice problems are at (https://library.fiveable.me/practice/ap-environmental-science).

Short answer: mangroves are a type of wetland, but not all wetlands are mangroves. Wetlands (per the CED) are places where water covers soil at least part of the year. Mangroves are coastal, salt-tolerant wetlands dominated by mangrove trees and found in tropical/subtropical shorelines. Why it matters for APES: both provide ecosystem services (water filtration, flood protection), but mangroves have extra coastal roles—nursery habitat for fish, storm-surge attenuation, and “blue carbon” storage. Both face similar human threats listed in the CED: coastal development, dredging, pollution (eutrophication, sedimentation), overfishing, and dam construction upstream that changes sediment/salinity. When you study Topic 8.4 (STB-3.E), expect questions about those services and human impacts and restoration/mitigation strategies. For the Fiveable study guide on this topic, see (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7). For broader Unit 8 review and practice, check (https://library.fiveable.me/ap-environmental-science/unit-8) and (https://library.fiveable.me/practice/ap-environmental-science).

Wetlands protect against flooding by acting like natural sponges: their saturated soils and dense vegetation (roots, peat, mangrove forests) store large volumes of water during heavy rains and storm surges, slowing runoff and reducing peak flow downstream. That stored water is released slowly, which lowers flood height and duration for nearby communities. Mangroves add storm surge attenuation by breaking wave energy with trunks and roots and trapping sediment that builds up coastal elevation over time. Wetlands also buffer shorelines (buffer zones) and reduce erosion, which limits damage during storms. These ecosystem services are exactly what the CED lists for wetlands (EK STB-3.E.2). For more AP-aligned review, see the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7), the Unit 8 overview (https://library.fiveable.me/ap-environmental-science/unit-8), and practice questions (https://library.fiveable.me/practice/ap-environmental-science).

Short answer: wetlands are any ecosystem where water covers the soil for at least part of the year; a marsh is a specific type of wetland dominated by herbaceous (non-woody) plants like grasses and reeds. More detail: the CED defines wetlands broadly (EK STB-3.E.1)—this includes marshes, swamps (woody plants/trees), bogs and peatlands (acidic, low nutrients), and mangroves (coastal, salt-tolerant trees). Marshes are often shallow, nutrient-rich, and good nursery habitat for fish; mangroves are a coastal wetland type important for storm surge attenuation and blue carbon. Wetlands provide services like water purification, flood protection, and habitat but are threatened by development, dredging, dams, eutrophication, and saltwater intrusion (EK STB-3.E.2–3). If you want a quick AP review, check the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and do practice problems for Unit 8 (https://library.fiveable.me/practice/ap-environmental-science).

Mostly because short-term economic pressures win over long-term ecosystem services. Developers drain and fill wetlands for housing, agriculture, or shrimp farms; dams and dredging alter sediment and water flow; and pollutants and nutrient runoff cause eutrophication that degrades wetland function (CED keywords: coastal development, dredging, dam construction, eutrophication, saltwater intrusion). People see immediate gains—land, jobs, cheaper food—while benefits like water filtration, flood protection, nursery habitat, and blue-carbon storage are less visible or valued. On the AP exam you should be able to describe both the threats and solutions: restoration, mitigation banking, buffer zones, protected status, and sustainable coastal planning reduce losses and restore services (EK STB-3.E.2 & STB-3.E.3). For review, check the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and practice questions (https://library.fiveable.me/practice/ap-environmental-science).

Dams change the downstream water regime and that harms wetlands. By trapping water and sediment, dams reduce peak flows and sediment/nutrient delivery that wetlands need to stay wet and build soils. Less frequent flooding leads to drying, peat oxidation, loss of blue carbon, and reduced water filtration and flood protection services (EK STB-3.E.2). Altered timing and reduced freshwater input can increase saltwater intrusion in coastal mangroves, shifting species composition and shrinking nursery habitat. Lowered sediment also increases erosion downstream and can reduce habitat complexity, decreasing biodiversity. These impacts are listed in the CED as threats from dam construction (EK STB-3.E.3). For a concise AP review, see the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and more Unit 8 resources (https://library.fiveable.me/ap-environmental-science/unit-8). Practice applying this to FRQs with problems at (https://library.fiveable.me/practice/ap-environmental-science).

The biggest human threats to mangroves are coastal development (building ports, housing, and shrimp farms), dredging and land reclamation, and conversion to agriculture/aquaculture—all of which remove habitat and fragment nursery areas. Dam construction and upstream water diversion reduce sediment delivery, changing salinity and causing saltwater intrusion or sedimentation shifts that harm mangroves. Pollution from agricultural runoff (nutrients causing eutrophication) and industrial waste degrades water quality. Overfishing and destructive fishing practices hurt the food web that mangroves support. These activities also release “blue carbon” when mangrove soils are disturbed, reducing storm-surge attenuation and other ecosystem services (EK STB-3.E.2–3.E.3). For AP review, study the CED keywords (dredging, sedimentation, saltwater intrusion, blue carbon) in the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7). More unit resources and practice problems are at (https://library.fiveable.me/ap-environmental-science/unit-8) and (https://library.fiveable.me/practice/ap-environmental-science).

Wetlands purify water in a few clear ways that show up on the APES exam (see EK STB-3.E.2): they slow water flow so sediments and particulates settle out, plant roots and soils trap and filter those particles, and wetland plants (like cattails and mangroves) take up excess nutrients (N and P). Microbes in wetland soils also transform pollutants—denitrifying bacteria convert nitrate to N2 gas, and other microbes break down organic contaminants—reducing eutrophication downstream. Wetland soils and organic matter adsorb heavy metals and some toxins, and UV/exposure and predation help reduce pathogens. Because wetlands store water and attenuate storm surge, they both filter and protect against pollutant pulses. Human threats (development, dredging, runoff, fertilizers) reduce these services, so protecting/restoring wetlands is a key solution you should mention for STB-3.E on the exam. For a concise review, check the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Overfishing harms mangrove ecosystems because mangroves act as critical nursery habitat and rely on balanced food webs to stay healthy (CED EK STB-3.E.2). Removing juvenile fish and key grazers reduces recruitment to adult populations and can trigger trophic cascades: fewer herbivores → more algal or macroalgal growth on roots → reduced oxygen and light, stressing mangrove seedlings and infauna. Overharvest of predators can cause mesopredator release, altering community structure and increasing disease or competition. Less fish biomass also weakens local fisheries and the socioecological services mangroves provide (storm-surge attenuation, blue carbon storage). This links directly to CED threats (EK STB-3.E.3: overfishing) you’ll be tested on. For a concise review, check the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and use AP practice problems (https://library.fiveable.me/practice/ap-environmental-science) to prep for related free-response prompts.

Agricultural pollutants harm wetlands and mangroves mainly through nutrient runoff, toxic chemicals, and sedimentation. Excess nitrogen and phosphorus from fertilizers and animal waste cause eutrophication: big algal blooms that block sunlight, then decompose and create hypoxic (low-O2) “dead zones” that kill fish and invertebrates and collapse nursery habitats (keyword: eutrophication). Pesticides and herbicides are toxic to aquatic plants and animals and can bioaccumulate up the food web, harming predators. Sediment from eroded fields buries wetland plants and mangrove roots, reduces light for photosynthesis, and alters water flow and substrate—making it harder for these habitats to filter water and buffer storm surge. These impacts match EK STB-3.E.2–3 in the CED (wetland services and threats). For AP review, see the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and practice problems (https://library.fiveable.me/practice/ap-environmental-science).

When you drain wetlands for commercial development you remove ecosystems that provide key services (water purification, flood protection, water filtration, and nursery habitat). That leads to more flooding and stronger storm surges, poorer water quality (more sedimentation and eutrophication), and loss of biodiversity—including fish and bird nurseries like mangroves. Draining also releases stored “blue carbon” (CO2) from peat and sediments, increasing greenhouse gases and causing saltwater intrusion into aquifers near coasts. Economically, you lose natural flood insurance and fisheries, and restoration/mitigation banking can be expensive and often can’t fully replace original functions. On the APES exam this maps to STB-3.E (human impacts on wetlands/mangroves)—know examples (dredging, coastal development, dam construction) and solutions (wetland restoration, buffer zones, mitigation banking). For a quick topic review see the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7), Unit 8 overview (https://library.fiveable.me/ap-environmental-science/unit-8) and practice questions (https://library.fiveable.me/practice/ap-environmental-science).

Industrial waste harms wetlands and mangroves in a few clear ways. Toxic chemicals and heavy metals from factories contaminate water and sediments, killing plants and invertebrates and bioaccumulating up food webs. Nutrient-rich effluent (N, P) triggers eutrophication—algal blooms, oxygen depletion, fish kills—and alters nursery habitat for fish and crustaceans. Sediment and chemical runoff smother mangrove roots and wetland vegetation, reducing their ability to filter water and attenuate storm surge (losing “blue carbon” storage). Acidic or saline industrial discharges can cause saltwater intrusion and soil chemistry shifts that stress peatlands and mangroves. These changes reduce ecosystem services (water purification, flood protection, habitat), which is exactly what the CED’s STB-3.E highlights. On the AP exam this shows up in both multiple choice and free-response questions asking you to describe impacts and propose mitigation (e.g., buffer zones, treatment, restoration). For a quick review, see the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and extra practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Yes—wetlands get legal protection at several levels. In the U.S. the Clean Water Act (CWA) is the big one: Section 404 controls dredge-and-fill permits (Army Corps of Engineers) for “waters of the U.S.”, which often includes wetlands. The Endangered Species Act can also protect wetland habitat for listed species. At the international level, the Ramsar Convention recognizes and encourages protection of important wetlands (including mangroves). Policies and programs also support restoration and incentives (e.g., wetland mitigation banking, buffer-zone requirements, conservation easements and agricultural easement programs). Enforcement and scope vary (WOTUS definitions, state rules), so protections aren’t absolute—development, pollution, and damming still threaten wetlands. For AP review, see the Topic 8.4 study guide (https://library.fiveable.me/ap-environmental-science/unit-8/human-impacts-on-wetlands-mangroves/study-guide/kxkfXkF2OACm1Tcwb8u7) and Unit 8 overview (https://library.fiveable.me/ap-environmental-science/unit-8). For practice questions on policy and mitigation concepts, try the practice bank (https://library.fiveable.me/practice/ap-environmental-science).