1Chapter 14: Coastal WetlandsCoastal Wetland: vegetated intertidal environmentSalt MarshesMangrovesVegetationDistributionClassificationGlobal Climate ChangeWetlands•Low energy environments Why Study Coastal Wetlands•Coastal wetlands currently make up about 30% of the wetlands in the lower 48 states, or approximately 27 million acres. •Marshes produce biomass measuring nearly 20 tons to the acre, making them four times more productive than the most productive farmland.•An estimated 80 percent of fish caught commercially spend some time in coastal wetlands or are dependent on food chains which can be traced back to these coastal environments Complex Ecosystems•81% of coastal wetlands are in the southeast •Gulf of Mexico region includes 51% •Pacific coast (excluding Alaska and Hawaii) contains less than 2%. •Most coastal wetlands (77%) occur in or adjacent to estuaries.US Wetland StatisticsThe 10 states with the most coastal wetlands: FloridaLouisianaSouth CarolinaTexasNorth CarolinaGeorgiaAlabamaNew JerseyCaliforniaMaine2Global Distribution of Coastal WetlandsMangroves can not survive in freezing temperaturesTidal CreeksSediments brought to the marsh through tidal creeksExtensive wetting and dryingVegetation controlled by inundationSharp Transition Between ZonesLow Marsh = neap low tide to mean tide levelHigh Marsh = mean tide level to spring high tideLow Marsh3High MarshMeadow is high in the intertidal zone Dominated by Spartina patensS. patensis less salt-tolerant than S. alterniflora. In the foreground is a small band of S. alterniflora.Distichlis spicataSalicorniacan be found in the highest part of the intertidalzone. They are very salt tolerant, and only about 5 cm high. Formation of a salt marsh1. Arrival of a seed or the rafting of a plant of the cord grass Spartinaalterniflora. 2. Once established grass spreads asexually through subterranean rhizome system. 3. Continued growth forms a baffle, encourages deposition of fine particulate sediment 4. Causes a rise of the sediment surface and makes the habitat more terrestrial. 5. Less salt-tolerant grasses invade 6. Eventual vertical zonation of grasses and a spread of the entire marsh system.Ice Raftingall of the plants in this picture are connected by a rhizomeColonization of a Seed4Salt/Tidal Marsh ZonesNew EnglandFlorida/Georgia•Marsh mussels enhances the growth of Spartina. •biodeposition of nitrogen-rich feces •byssal threads also help bind the sediment and retard erosion. •the fiddler crab also aids in Spartinagrowth by burrowing and aerating the sedimentYoungIntermediateOldZonation and Sediment PropertiesSediment delivery through tidal creeks (suspended fine grained material) or overwash/storm deposits (sands). bog = any peat accumulating or moss-lichen wetland marshes = wetland dominated by grass-like plants swamps = forested and scrub-shrub wetlandscypress swamps in the southern United States hardwood swamps or floodplainssalt-water swamps known collectively as mangrovesMangroves Were regarded as muddy, mosquito and crocodile infested swamps. In the past their removal was seen as a sign of progress. ZonationHabitat RequirementsDistributionCoastal Protection5Mangrove ZonesRed Mangroveedge of the shoreline where conditions are harshestreddish prop rootsincrease stability and supply oxygen to underground roots grow to heights of 25 m, average 6 mBlack Mangrovelong horizontal roots and root-like projections pneumatophoresprovides oxygen to the underground and underwater root systemsallows growth in oxygen depleted soils (anaerobic:oxygen-free)grows 20 mWhite Mangroveoccupy higher land than the red and black mangrovesno visible aerial rootsleast cold-tolerant of the three mangrove speciesrapid growth to heights of 15 m Temperature Requirementsabove 19° C fluctuations can not exceed 10° C can tolerate temporary freezing episodesTidal Flushingsalinity reduces competitionsupplies nutrients/ removes wastetransports propagules (seedlings) 50 species between 25° N and 25° S Warm surface current can extend the geographic extent Africa, Australia, and New Zealand (35-40° S)Japan, Florida, Bermuda, and the Red Sea (30-32° N)6Coastal ProtectionTsunami Dampening by Mangroves•Industrialized shrimp firms have exploited Asian mangroves•Shrimp cultivation over 8 billion tonnes a year in 2000•72% of the shrimp farming is confined to Asia •Shrimp farms are abandoned every 2-5 years, leaving behind toxic waste and destroyed ecosystems Tsunami Dampening by Mangroves•Expansion of shrimp farming = reduction of mangrove swamps•Java lost 70% of its mangroves, •Sulawesi 49% •Sumatra 36%•India destroyed nearly 50% between 1963 and 1977•Five-star hotels, golf courses, industries, and mansions•Dilute the Coastal Regulation Zone (CRZ) 500 meter buffer along the beach Tsunami Dampening by Mangroves•Since the 1700s, more than half of all of the wetlands in the lower 48 states have been lost•U.S. Fish and Wildlife Service report estimates that by the mid 1970s, over half of all saltmarshes and mangrove forests present in pre-colonial times had been destroyed. •California has lost over 90% of its wetlands. •Florida and Louisiana have lost about half of their wetland area. •Louisiana alone is losing between 16,000 and 25,000 acres of wetlands a year, which is the highest sustained wetland loss rate in the country. Wetland LossWhy are coastal wetlands disappearing?•farming or grazing •filled or dredged for roads, houses, golf courses, marinas, and other development •land subsidence, and sea level rise•Pollution, changes in water flows, and invasion by weeds or other non-native plants and animals Population pressures•Coastal populations have increased steadily since 1970. •Currently, over half the population of the United States live in coastal counties •Trend is expected to continue in the coming decades7Sea Level Rise•A few inches of rise in sea level can mean that the coastline moves hundreds of feet inland•Coastal wetlands can move inland with rising sea level •Developed areas and human structures interfere with this natural migration of coastal habitats•Coastal wetlands become submerged, eventually dying and eroding away.Good News•Rate of coastal wetland loss has declined during the past decade •In the 1950s, the rate of coastal wetland loss was about 46,000 acres a year •Today it is around 20,000 to 25,000 acres a year. •Federal and state regulations