All About Mangroves

 Photo by Jessica Satterthwaite, UWT 2011

High Biodiversity
     
      Mangrove trees have aerial roots and special filtering systems which allow them to grow in the mud and sands of salty waters, on the edge of land and sea, against waves, floods and all odds. They currently inhabit 181,000 square kilometers of tropical and sub-tropical coastlines in the world. (Alongi, 2002) The global distribution of mangrove forests can be found here in a map from a 2007 National Georgraphic magazine:
 Distribution Map ("Friends of mangroves," 2012).

 Photo by Jake Asplund, UWT 2011

     Much of the world's biodiversity is housed in these forests at one time or another, as is seen in the photographs of the white faced monkeys (left) and the  pygmy anteater (right), finding food and shelter in the Pacific Coast mangrove trees of Costa Rica. Besides mammals, mangroves are also important breeding grounds for birds, fish, shellfish, and crustaceans.  These salt marsh forests are however less species rich than terrestrial tropical rain forests.         
     Mangroves are halophyte trees that make up about 9 taxonomic orders and 20 families.  The highest biodiversity of mangroves themselves, as well as largest area, can be found in Indonesia, with 51 of the 70 species of mangroves represented (Alongi, 2002). On the Florida coast of the United States only 4 species of mangroves remain ("Mangrove Action Project", 2012).


High Rates of Deforestation

    Since 1980, 35% of the world's mangrove forests have been lost world-wide, a higher rate of deforestation than even the more recognized tropical rain forests (Martinuzzi et al, 2009). Historically mangroves were largely fragmented for agriculture and timber extraction, producing charcoal, furniture, as well as medicine and alcohol, but with industrialization and the potential for sustainable practices, the largest threats to mangroves currently are  aquaculture and human coastal development.   Deforestation has been worst in Vietnam, Malaysia, and Madagascar ("FAO UN," 2012).
     Originally viewed by most people as ecologically and economically insignificant, mangroves have been more recently discovered to be quite the opposite. After the Indian Ocean tsunami of 2004, it was reported that mangrove forests significantly decreased the impact of tsunami waves with hydraulic resistance from sea floor roughness and vegetation  (Tamin et al, 2011).  It has also been shown that mangrove ecosystems can reduce sea level rises during hurricanes and can reduce erosion along coastlines (Krauss et al, 2009).  The coastal protection value of mangroves now exceeds direct-use values by over 97% (Tamin et al, 2011).  

Restoration


    As mangroves have become recognized for their ability to prevent erosion and decrease the impact of tropical storms, there has been a rush to protect and restore them.  Most of these

Photo by Jake Asplund, UWT 2011

restoration efforts have focused mainly on replanting and not on the natural ecology of mangroves, sometimes planting monocultures or non-native species, and with little success.  Also it has been noted that without fixing the hydrology and basic issues limiting natural recruitment in the first place, then regrowth may not be possible(Lewis, 2004).  By fixing those issues first, mangrove regrowth can occur naturally, with replanting as a last resort.
      There has been some success in their conservation already, as mangrove forest areas are increasing in Bangladesh, Kuwait, Cuba, and Ecuador("FAO UN," 2012). Mangrove restoration projects have created jobs for locals and range from large expensive government projects to small unfunded community based ones like the one in this photograph(left).  Shown here student volunteers from the University of Washington plant mangrove propagules found naturally floating in the waters of Costa Rica, and plant them in long PVC pipes to protect the seedlings in what has been called the  Riley Encased Method(REM).  This method was invented by a computer scientist and has worked for mangrove afforestation in Florida with moderate success, and little to no success in Costa Rica ("mangrove", 2012). 




                                                                                            Climate Change
      
      With the emergency state of erosion found in some places like Ecuador and Costa Rica, where you can see abandoned houses and hotels next to rapidly receding coastlines, the conservation, protection and regrowth of mangrove forests is essential.   This is why it is so important to look at the future of mangroves with the impacts of climate change, while awareness and concern are high, to develop a long-term science based plan for conservation and restoration of mangroves that is robust.
      From the human induced increase in green house gases,  it is predicted that there will be increases in global temperature, rises in sea levels, and most likely related increases in storm frequency and intensity.  It is also known that the frequency of El Nino-Southern Oscillation(ENSO) events are also increasing and may be related to  climate change.   As mangroves are most sensitive to long periods of flooding,too cold temperatures and changes in salinity, the current mangrove forest distribution may be threatened  If huge efforts and funding are going into restoration, it better be in the right spot, not one that is going to disappear in 10 years. 


Click on the links here or at the top of the page to see how mangroves will be affected by different aspects of climate change along with feedback flow charts:  
Rise in global temperature, Increasing El Nino, Rising Sea, Increasing Storms

Click here or at the top of the page to see what should be done:TO DO