What Are Mangroves ?

Mangroves of Florida 

Introduction

Though just a minute percentage of land around the world, the mangroves of Florida  are steadily declining, yet provide some of the most vital mechanisms for the marine and estuarine environments surrounding them. Defined as, “a tree, shrub, palm or ground fern, generally exceeding one half meter in height, that normally grows above mean sea level in the intertidal zone of marine coastal environments and estuarine margins," mangroves impact Earth’s ecosystems considerably despite their small size (6).  Ranging from the Cedar Keys of North Western Florida, down to the Florida Keys and Bahamas, the mangroves of Florida are approximated to constitute 225,000 Ha or 555,000  acres of land (5). Specifically in Southern Florida, mangroves provide some of the best nutrient, species, and biodiversity support, making this ecosystem one of the most biologically productive ecosystems in the world (4). Housing over 1300 species world wide, many of which endemic to those locations, mangroves limited intertidal and saltwater mix make this ecosystem even more unique and important(4). 

Majority of distribution is between 30 degrees North and 30 degrees South (3).  

 History 

  Most mangroves have been dated back more than 50 millions years ago, some even 100 million years ago.  Greatly attributed to continental drift, the diversity and spread of mangroves spans all over Earth (6). While there is no exact origin or path of dispersion, mangroves share similar adaptations, despite evolving during different time periods. Most notably, mangroves thrive best in tropical climates, adapt to salinity levels, rest within tidal fluctuations, and have buoyant seedlings. Mangroves species over time have historically done best in conditions warmer than 66 degrees Fahrenheit as well as conditions that rarely go below freezing, or 32 degrees Fahrenheit(5). Mangroves are considered to be facultative halophytic species- meaning that salt water is not required for growth(5). Mangroves have adapted to living in freshwater and saltwater habitats to outlive any competing species.  Tidal Fluctuations bring in necessary nutrients for growth and sustainability. Likewise, in order to spread and disperse the seedlings of mangroves tidal fluctuations must occurs (5,6). 

Florida Mangroves Biomass Distribtion (Mg/ha) (1). 

Florida Mangroves Height Distribution (meters) (2)

While there are approximately 80 species of mangrove plants only 4 are native to Florida                (Maikut,  2004) 

Black Mangrove (Avicennia germinans) (5)

Black mangroves’ first noticeable difference is its horizontal growing roots and small roots that grow around the base of the plant providing oxygen known as pneumatophores. Black Mangroves grow at marginally higher elevations than Red Mangroves, and can tolerate extreme weather conditions best. As a result of its horizontal growth, Black Mangroves grow slightly shorter than Red Mangroves. The unique features of Black Mangroves are : black bark, deep green leaves, pointy tips, and  white flowers ( bloom in spring only) (4,5).

White Mangrove (Laguncularia racemosa) (5)

White mangroves grow on higher lands than both the black and red mangroves.  White mangroves are the least cold tolerant of the mangroves in Florida and therefore often grow more southerly than other mangrove species. The light green leaves amongst the three inch round leaves can further help to  identify the white mangrove (4,5). 

Red Mangrove (Rhizophora mangle) (5)

Red Mangroves can be easily recognized for it red-ish roots that stem from tis truck. Red Mangroves develop in the roughest conditions along shorelines, yet still amazingly can grow up to over 20ft in height. It roots range from 1to 3 feet as well. Also, by far the most abundant in Southern Florida, a Red mangrove's growth and spread is determined by temperature. The Red Mangroves can further be identified by its leaves, ranging from 1-2 inches, its blunt tip, and its deep green shine (4,5). 

Buttonwood Mangrove (Conocarpus erectus) (5) 

Similar to the white mangrove, the buttonwood species grows up at higher elevations as well as the upland transitional zone. Also, buttonwood's inability to resist frost limit it to growing in only southern Florida. The buttonwood can be recognized for its flowers button-like appearance, which grow in clusters.  The leaves are often leather-like, and have a pointed edge (4,5).  

Impacts

Human Impacts on Mangroves

           Humans have left a profound impact on mangrove forests, and it’s not a good thing. Mangroves are very specific to the ecosystem that they live in; therefore, any alteration made to their environments can result negatively. The largest influences on mangroves come from urban development and water management practices (7). With an increase in human population, people need more land to build and expand; the ideal location of mangroves becomes attractive for development. The coast is also a prime location for aquaculture and shrimp farming, so more clearing occurs because of this. In Florida, mosquito control activities are additional reasons for the degradation of the valuable land. When these forests are cleared, their service as a natural buffer for winds and waves decreases and humans are put in greater danger when harmful storms come around (8). Water management activities, including diversion projects and dams, alter the salinity levels of the mangrove forests. Because of this change and the sensitivity of the forests, mangroves are not able to thrive at different pHs. Water management activities often lead to pollution or erosion, both also causing suffocation of trees when oxygen cannot reach the roots. Chemicals, such as pesticides, flow into the forest, killing fish and throwing off the nutrient balance of the ecosystem (9,10). The fish that normally eat leaf litter and help with decomposition die off.

Status

Mangroves are not doing very well. According to BioScience Oxford Journals, their status is reflected by a worldwide 35% decrease in mangrove forest sizes (11). Other data shows a 2.1% decrease in mangrove forest sizes per year since 1980. In the Americas alone, there is a per year loss of 3.6% (11).

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Negative Consequences

              Consequences of mangrove forest loss have been shown through economic losses and tolls on the ecosystem food web. Economic losses include the costs to prevent erosion, the loss of money by fish based industries, and the necessary means to manually regulate water quality (13).

            Additionally, the food chain shifts when fish, at the very bottom, experience a sharp decline. Mangroves provide the perfect grounds for fish breeding and nursing, so without having fish, other species die (12).

Degradation of terrain and mangroves over time (22)

Species 

              The mangroves of South Florida are home to 75% of all game fish and 90% of all commercial fish in Florida (12). These mangroves are also home to some of the greatest diversity in species. As mangroves are disappearing, however, this wildlife is going extinct. Some of these species at risk include songbirds, estuarine birds, and reptiles. More specifically, there are yellow warblers, ospreys, and alligators that will soon be left without an ecosystem. 46 of the state listed species are from South Florida, as well as 9 of the federally listed species (12). The federally listed species are such as the Florida panther, Key deer, Lower Keys rabbit, West Indian manatee, Big Cyprus fox squirrel, White Crowned pigeon, and mangrove tree crab.

Florida Panther nationalgeographic.comhundreds-of-panther-sightings-reported (14).

Key Deer (15)

Table

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 Damages 

Based on the human impacts of mangroves, if no changes occur, the future of mangroves is negative. Actions such as dredging and filling the mangroves, for example, will lead to death. This is because still water covers the roots, which makes it impossible for oxygen to reach the roots, and the mangroves thus cannot survive (19). The mangroves can also be damaged by water pollution, which leads to destruction too. This water pollution is a result of herbicides, oil spills, and other pollutants contaminating the water. Herbicides are simply too strong for the mangroves which are highly sensitive to them, and during oil spills, oil covers the roots limiting oxygen transportation. Urban development in the mangroves causes a mass destruction and immediate death of the mangroves. These human impacts leave a negative outlook for the mangroves because everything humans are doing right now leads to death (6). Furthermore, it is believed that over the next 25 years, the biggest threat to the mangroves are believed to be unrestricted clear cutting, aquaculture, and overexploitation of fisheries. Loss of biodiversity is also expected to continue if nothing is done to be changed. By 2025, unless something is done, the future of mangroves will be dependent on technology in areas such as genetics(19).

 Future Restoration

The future is not necessarily horrible for mangroves . This is because of all the restoration projects in place as well as projects that can still be added. The popularity of these projects is also increasing worldwide. Also, coastal aquaculture is decreasing worldwide. Another positive is that population growth is supposed to decline in about 50 years (6). Technology is also improving in areas that will improve the mangroves. Methods of aquaculture, although it is not great or the mangroves, is improving and the harm is not as great. However, the human impacts on mangroves are difficult to predict because of lack of knowledge regarding canopy and root production, root respiration, physiological information, effects of greenhouse gas and sea level change, and effects of excess nutrients (6). The Charter for Mangroves is a place to start in the movement towards mangroves being conserved and managed on a sustainable basis. Local and national governments simply need to supply adequate resources for this to be done. For example, in Australia, they rely on legislation for protection, and they have set up various commissions and committees to help with the conservation and protection process(6). One simple method to improve the mangroves is by simply planting more to help against floods and other natural disasters. Overall, eliminating deforestation and limiting aquaculture would be big steps in the right direction.

Mangroves converted to aquaculture (17)

Replanting of Mangroves(18)

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Bibliography 

1.   (n.d.). Retrieved November 30, 2014, from http://fcelter.fiu.edu/data/GIS/maps/Mangrove_biomass_map.jpg 


2.    (n.d.). Retrieved November 30, 2014, from http://fcelter.fiu.edu/data/GIS/maps/Mangrove_biomass_map.jpg

3.     (n.d.). Retrieved November 30, 2014, from http://fcelter.fiu.edu/data/GIS/maps/Mangrove_height_map.jpg

4.     
 Ecology of Mangroves. (n.d.). Retrieved November 30, 2014, from http://jrscience.wcp.muohio.edu/fieldcourses04/PapersMarineEcologyArticles/EcologyofMangroves.html

5.    
 





FLMNH Ichthyology Department: South Florida Aquatic Environments. (n.d.). Retrieved November 30, 2014, from https://www.flmnh.ufl.edu/fish/southflorida/mangrove/distribution.html

6.    Mangrove Watch. (2013, January 1). Retrieved November 30, 2014, from http://www.mangrovewatch.org.au/index.php?option=com_content&view=category&layout=blog&id=52&Itemid=300137

7. Mangrove forests: Threats. (n.d.). Retrieved November 30, 2014, from http://wwf.panda.org/about_our_earth/blue_planet/coasts/mangroves/mangrove_threats/

8.Mangroves. (n.d.). Retrieved November 30, 2014, from http://oceanfocus.org/focus-areas/threatened-habitats/mangroves/

9.Global Warming and Mangroves - National Wildlife Federation. (n.d.). Retrieved November 30, 2014, from http://www.nwf.org/Wildlife/Threats-to-Wildlife/Global-Warming/Effects-on-Wildlife-and-Habitat/Mangroves.aspx
10.Economic consequences of mangrove removal. (n.d.). Retrieved November 30, 2014, from http://www.ozcoasts.gov.au/indicators/econ_cons_mangrove_removal.jsp

11.Mangrove Forests: One of the World’s Threatened Major Tropical Environments. (2001). Bioscience.oxfordjournals, 51(10), 807-815.

12.Endangered Species - Mangrove Action Project. (n.d.). Retrieved November 30, 2014, from http://mangroveactionproject.org/endangered-species/
13.Pollution is detroying the mangroves on coastal Bali | GRID-Arendal - Environmental Photo Library. (n.d.). Retrieved November 30, 2014, from http://www.grida.no/photolib/detail/pollution-is-detroying-the-mangroves-on-coastal-bali_048a
 14.Hundreds of Panther Sightings Reported in Florida. (n.d.). Retrieved November 30, 2014, from http://voices.nationalgeographic.com/2013/08/15/hundreds-of-panther-sightings-reported-in-florida/
15.National Geographic Photo Contest 2012. (n.d.). Retrieved November 30, 2014, from http://ngm.nationalgeographic.com/ngm/photo-contest/2012/entries/170273/view/

16.https://www.flmnh.ufl.edu/fish/SouthFlorida/mangrove/images/oil.JPG

17.(n.d.). Retrieved November 30, 2014,https://www.flmnh.ufl.edu/fish/SouthFlorida/mangrove/images/oil.JPGhttp://www.solutions-
18 .Case Study: Maiden Island, Antigua  Mangrove Habitat Restoration Project. (n.d.). Retrieved November 30, 2014, from http://www.reefball.com/reefballcoalition/mangroves.htm 

19. http://cmbc.ucsd.edu/content/1/docs/alongi%202002.pdf
20.Luther, D., & Greenberg, R. (2009). Mangroves: A Global Perspective on the Evolution and Conservation of Their Terrestrial Vertebrates. BioScience, 59(7), 602-612.
21. Polidoro, B., Carpenter, K., Collins, L., Duke, N., Ellison, A., Ellison, J., ... Koedam, N. (2010). The Loss of Species: Mangrove Extinction Risk and Geographic Areas of Global Concern. Plosone, 5(4).

22. Deep Freeze and Sea Breeze: Changing Land and Weather in Florida : Feature Articles. (n.d.). Retrieved December 4, 2014, from http://earthobservatory.nasa.gov/Features/DeepFreeze/deep_freeze3.php