Mangroves

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Mangroves


What are Mangroves?

  • Groups of trees and shrubs that live in the coastal intertidal zone
  • 80 different species (from shrubs to 200-foot-high trees)
  • Slow moving waters allow fine sediments to accumulate and build up the muddy bottom
  • Some have dense tangles of prop roots or buttresses that allow the trees to handle the daily rise and fall of tides
  • Some have snorkel-like roots called pneumatophores that stick out of the mud to help them take in air[1]

Where are They Found?

  • Only grow at tropical and subtropical latitudes near the equator
  • Grow in areas with low-oxygen soil
  • Most in Southeast Asia, many in Florida[1]

What Benefits Do They Offer?

  • Stabilize the coastline, reducing erosion from storm surges, currents, waves, and tides
  • Intricate root system is attractive to fish and other organisms seeking food and shelter
  • Nursery for commercially important juvenile fish
  • Habitats for oysters, crabs, shrimp, and birds
  • Carbon sequestration and storage, decreasing the effect of global warming
  • Stabilize shorelines and prevent erosion
  • Buffer against hurricanes and tropical storms[1]
  • Mangroves intercept pollutants and land derived nutrients before they contaminate deeper water
    • Nutrient transport from land to estuaries is one of the main agents of ecological change in coastal areas[2]

What are the Stressors of Deforestation?

  • Estimated that at least half of the world’s mangroves have been lost and continue to be destroyed at a rate of about one percent per year[1]
  • Stressors
  1. Coastal development driven by tourism and growing populations[1]
  2. Aquaculture, particularly shrimp farming[3]
    • Mariculture has been reported as responsible for 50% loss of mangroves in the Philippines and 50-80% in Southeast Asia
    • These ponds often have short life spans due to toxin accumulation and sulfide acidification, causing these pond owners to move to a new section of mangrove, furthering the destruction of mangrove forests[2]
  3. Agriculture run-off carrying pesticides and herbicides
  4. Man-made changes in tidal or river flow that starve the system of sediment input
  5. Sea level rise[1]

What are the Side Effects of Deforestation?

  • Loss of mangroves reduces the amount of carbon sequestration possible and releases carbon stored in the soils, worsening the greenhouse effect
  • Coastal communities left unprotected from storms and hurricanes
  • Deforested shorelines are subject to greater rates of erosion and are unable to keep pace with sea level rise[1]
  • One of the world’s most threatened tropical ecosystems with global loss exceeding 35%
    • There is a pattern of reduced mangrove forest area for nearly all countries containing them, especially countries with large mangrove areas[2]
    • In Americas, mangrove deforestation is 2,251 km2 per year, which is higher rate than tropical rainforest deforestation[4]

What lives in the Mangroves?

  • Birds roost in the canopy
  • Shellfish and organisms attach themselves to the roots, such as barnacles, oysters, crabs, sponges, anemones
  • Snakes and crocodiles hunt there
  • Nectar source for bats and honeybees
  • Juvenile fish find shelter there during there vulnerable first weeks[3]

What are the Common Types of Mangroves?

Red Mangrove[5]

Grows along the edge of the shoreline where conditions are harshest
Tangled, reddish prop roots and gray bark over a dark red wood
Grows to heights of 80 feet
Clusters of white flowers bloom during the spring months

Black Mangrove[5]

Long horizontal roots with pneumatophores
Bark is dark and scaly
Grows to heights of 65 feet
White flowers blossom in spring

White Mangrove[5]

Occupying higher land than the Red and Black Mangroves
No visible aerial roots, but can develop peg roots
The least cold tolerant
Grows to heights of 50 feet
Produce greenish-white flowers in spikes in spring

Buttonwood Mangrove[5]

Found in the upland transitional zone
Sensitivity to frost
Button-like appearance of the flower heads that grow in branched clusters, forming cone-like fruit

How Are They Linked to Coral Reefs?

  • Provide nutrients to neighboring ecosystems such as coral reefs and sea grass beds
  • Nearby coral reefs suffer further pressure from sedimentation when mangroves are removed and can no longer filter the water[1]
  • Mangroves in the Caribbean have a strong influence on the fish populations in reefs near them
    • The largest herbivorous fish in Atlantic, Scarus guacamaia (rainbow parrotfish), is dependent on mangroves and has become locally extinct when they are gone[4]
      • Decreased amount of herbivores will cause reefs to become less resilient to algal overgrowth
    • Fisheries productivities are likely to decrease without mangroves
  • In a study in Belize comparing mangrove-scarce reefs to mangrove-rich reefs, the biomass of nearly every fish studied was much greater in the mangrove-rich areas
    • Biomass of the blue striped grunt on patch reefs in the mangrove-rich area increased by 2667%
    • Biomass of all 6 species studied in the patch reefs increased from 191% to 2667% in mangrove-rich areas[4]
  • Mangroves act as intermediate nursery between seagrass beds and patch reefs[4]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 http://www.habitat.noaa.gov/abouthabitat/mangroves.html
  2. 2.0 2.1 2.2 http://vb3lk7eb4t.search.serialssolutions.com.libproxy.lib.unc.edu/?&url_ver=Z39.88-2004&url_ctx_fmt=info:ofi/fmt:kev:mtx:ctx&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.atitle=Mangrove%20forests%3A%20One%20of%20the%20world%27s%20threatened%20major%20tropical%20environments&rft.aulast=Valiela&rft.date=2001&rft.epage=815&rft.genre=article&rft.issn=0006-3568&rft.issue=10&rft.jtitle=BIOSCIENCE&rft.pages=807-815&rft.spage=807&rft.stitle=BIOSCIENCE&rft.volume=51&rfr_id=info:sid/www.isinet.com:WoK:UA&rft.au=Bowen%2C%20JL&rft.au=York%2C%20JK&rft_id=info:doi/10.1641%2F0006-3568%282001%29051
  3. 3.0 3.1 http://ngm.nationalgeographic.com/2007/02/mangroves/warne-text/6
  4. 4.0 4.1 4.2 4.3 http://vb3lk7eb4t.search.serialssolutions.com.libproxy.lib.unc.edu/?ctx_ver=Z39.88-2004&ctx_enc=info:ofi/enc:UTF-8&rfr_id=info:sid/ProQ%3Apqdiearthsci&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.genre=article&rft.jtitle=Nature&rft.atitle=Mangroves+enhance+the+biomass+of+coral+reef+fish+communities+in+the+Caribbean&rft.au=Mumby%2C+P+J%3BEdwards%2C+A+J%3BArias-Gonzalez%2C+JE%3BLindeman%2C+K+C%3BBlackwell%2C+P+G%3BGall%2C+A%3BGorczynska%2C+MI%3BHarborne%2C+A+R%3BPescod%2C+CL%3BRenken%2C+H%3BWabnitz%2C+CCC%3BLlewellyn%2C+G&rft.aulast=Mumby&rft.aufirst=P&rft.date=2004-02-05&rft.volume=427&rft.issue=6974&rft.spage=533&rft.isbn=&rft.btitle=&rft.title=Nature&rft.issn=00280836
  5. 5.0 5.1 5.2 5.3 http://www.flmnh.ufl.edu/fish/southflorida/mangrove/profiles.html