||Mangroves - Incredible Salt Water Trees that Give Life Every Day
|Cozumel is a beautiful island in the Caribbean that probably would not exist as it does today without mangroves along its shore. Mangroves are tropical, salt tolerant trees found throughout the equatorial seas and scientists are now beginning to make us fully aware of the critically important roles they play in our global eco-systems.
Mangroves are found along tropical and subtropical coastlines between 25 degrees north and south of the equator. These ecosystems support many essential ecological functions, so significant losses of mangroves can and do have serious consequences.
At one time, 60-75% of the earth’s tropical coastline and semi-tropical regions were lined with mangrove forests, but not any longer. In the past two decades, it has been recorded that 35% of mangrove forests have been lost. These losses exceed the rate of destruction for tropical rain forests and coral reefs. This makes mangroves one of the most threatened habitats in the world.
Destruction of mangrove forests is occurring globally. The concern is that the loss of mangroves is a loss to the adjacent ocean ecosystems. Potential effects range from the damage or destruction of coral reefs to the decline of food fish populations. Mangroves are not only an ecosystem in and of themselves, but they often occur in conjunction, and have strong interactions, with coral reefs, sea grass beds, and the surrounding terrestrial areas.
Mangroves are critically important because they intercept land-derived nutrients, pollutants, and suspended matter before they have the chance to reach deeper water and other ecosystems such as coral reefs and sea-grass beds. For example, mangroves and sea grass beds filter fresh water discharges from land promoting the growth of coral reefs offshore. The high sediment loads from coastal erosion would be detrimental to coral reefs, but mangroves prevent the sediment from reaching the reefs. Usually, the fine sediment under mangroves act like a “sink space” for a variety of heavy (trace) metals from the seawater. In areas of the world where mangroves have been removed for development purposes, the disturbance of these underlying “sink space” sediment often creates problems of trace metal contamination of seawater and the total destruction of organisms living in and near the disturbed area.
Mangrove disturbance effects can be lethal to all dependent organisms given enough contaminants however, more frequently the effects are sub-lethal. This means the mangrove dependent organisms aren’t killed by an uprooting of mangroves but instead the exposure to disturbed contaminants result in effects such as immunosuppression, temporary illness or hormonal interference through chemical mimics, such as biocides and industrial chemicals.
Mangroves can better endure such human assaults than coral reefs, however, there is a large and essential community of decomposers and consumers resident in the mangroves, many of which migrate to the reefs as adults. These, especially juvenile forms, can be impacted or destroyed by chemical or other forms of pollution.
Once established, roots of mangrove plants provide a habitat for oysters and other organisms which help to impede water flow, thereby enhancing the deposition of sediment in areas where it is already occurring. Mangrove forest productivity is based on the microbial breakdown of plant matter by bacteria and fungi. This decaying organic matter serves as the basis for a very elaborate food chain. Mangroves’ intricate root systems provide habitats for a host of invertebrates such as mussels, sponges, tunicates, hydroids and oysters, as well as the juvenile stages of many fish. So the roots themselves, the mud, the branches and the brackish water around mangroves all play host to literally thousands of different living organisms.
|Life In A Mangrove Forest|
Regardless of species or adaptations, mangroves share important characteristics that make them the basis of marine ecosystems. The combination of protection and food gives young animals a better chance for survival than they would have in the open sea. Mangrove swamps are imporant to the environment because they act as nurseries for adjacent marine ecosystems like coral reefs. Many of the species they nurture are commercially and economically important such as shrimp and prawns.
Because they are large plants, mangroves hold the soil well, protecting the habitat and coast from erosion from storm surges, waves and weather. This is especially important in a tropical setting where violent storms are frequent. Many tropical islands like Cozumel simply would not exsist if it weren’t for the combination of coral reefs and mangroves protecting them from erosion caused by ocean waves and currents.
Mangroves also create great homes for a wide array of bird species. Cozumel Island off Yucatan's eastern coast is home to three bird species found nowhere else on Earth: the Cozumel Emerald, Cozumel Vireo and Cozumel Thrasher. It is also home to the Caribbean species of Western Spindalis, found nowhere else in Mexico, as well as the Smooth-billed Ani. There are a number of interesting endemic subspecies on the island as well, including Cozumel Wren, Golden Warblers, Rufus-browed Peppershrike and the Bananaquit.
Mangroves are non-homogeneous; meaning that in most cases several different species of mangroves and other vegetation co-exist. Mangroves are also highly interactive with their surroundings including the land, the sea, and the atmosphere above. Therefore, the various vegetation, tidal inundation zones, and adjacent marine and terrestrial areas should be included in the conservation of mangroves. In fact, under the correct conditions, mangroves can grow and thrive in a variety of coastal environments and only take two decades to reach the biomass of other natural forests.
In a harsh environment, mangroves have evolved a special mechanism to help their offspring survive. All mangroves have buoyant seeds suited to dispersal in water. Unlike most plants, whose seeds germinate in soil, many mangrove plants’ seeds germinate while still attached to the parent tree. Once germinated, the seedling grows either within the fruit or out through the fruit to form a seedling which is ready to produce its own food via photosynthesis. When the seedling is mature it drops into the water where it can then be transported great distances. Seedings can survive drought and remain dormant for weeks, months, or even over a year until they arrive in a suitable environment. Once a seedling is ready to root, it will change its density so that it is weighted toward the broad root end and they float correctly oriented in the water. In this position, it is more likely to become lodged in the mud and root. If it does not root, it can alter its density so that it floats off again in search of more favorable conditions.
Red mangroves grow above the waterline on stilt-like roots. They obtain fresh water by filtering seawater through its adapted roots, which remove the salt by reverse osmosis. Black mangroves have roots that grow in the sediment below the waterline. These mangroves aerate their roots with snorkel-like tubes which carry air from above the surface to the roots. Some of these eliminate salt through sacrificial leaves or have special salt glands in their leaves. White mangroves lack specialized adaptations. They are very saltwater tolerant but thrive high on the tideline where they don’t need special root adaptations. These mangroves receive sufficient fresh water runoff to survive. Buttonwood or grey mangrove is generally found near salt water, but cannot tolerate completely waterlogged soil conditions as those occupied by the other mangrove species. It is usually found growing in association with the white mangrove forest, but may also occur in low spots within the coastal zone. Typically the red mangrove forms a fringe along the water’s edge and black and white mangroves generally grow inland from the red mangrove.
The mangrove plant family is valued for its protection and stabilization of low lying coastal lands and its importance in coastal fishery food chains. Mangrove forests protect uplands from storm winds, waves, and floods. Mangroves can help prevent erosion by stabilizing shorelines with their specialized root systems. Mangroves provide protected nursery areas for fishes, crustaceans, and shellfish. The relationship between mangroves and their associated marine life cannot be overemphasized.
In summary mangroves are important to worldwide marine ecosystems because they provide:
Water filtration of nutrients and sediments
Fish Habitat (over 75% of commercial fish need mangrove wetlands as nursery habitat)
Carbon Dioxide Sequestration
With this better understanding of how critical mangroves are to an island’s health it becomes clear that Cozumel has enjoyed thousands of years of healthy mangroves. From the crystal clear sea water that surrounds it to its beautiful coral reefs, Cozumel owes a huge debt of gratitude to the mangroves yet they are in constant danger of extinction on the island.
|Cozumel Mangroves in Peril|
The major threat to mangroves is human impact, including fish farming, agriculture, urbanization, and forestry. Mangroves are also taken out as the land is converted to salt flats or used industrial or urban development.
In 2007 and 2008 Cozumel has seen serious threats to this valuable resource, most notably the controversial Trump Project which would bury half the virgin east coast of Cozumel under asphalt destroying a sanctuary for turtles and migratory birds. Also the Caleta (Marina Fonatur) project in front of Paradise Reef would destroy mangroves and fill underground caverns thereby impacting the water table from which Cozumel obtains its water. These mangroves are located at the proposed entrance of the new marina. Supposedly this project at the Caleta marina has been delayed until modifications to the building plan can be put in place to avoid damaging the environment. However, environmentalists on the island are maintaining a "wait and see" vigilance over the matter.
UPDATE: March 2009 this development project got underway. Environmentalists were powerless as acre after acre of mangrove and virgin jungle were felled to make way for the mulit-million dollar marina.
Another development threat to mangroves exists at Rancho Chaká which is located in front of Palancar Reef and is the site of a planned subdivision with roads. Mangroves were devastated months before Profepa finally decided to act and close down the project so that the mangroves can be replaced. The delicate ecosystems were destroyed with power saws under the guise that they were clearing dead vegetation left in the wake of Hurricane Wilma. Experienced divers have reported the proliferation of algae and coral bleaching in the areas where mangroves have been damaged or destroyed. Hundreds of meters of mangroves have been destroyed in the Marine Park without intervention by the authorities and two new hotels are planned in the area of Nachi Cocom and San Francisco Beach.
Yet another threat for some of Cozumel’s mangroves is the grounded vessel “Princess Maya” which ran aground during Hurricane Dean. This is a very old boat used for tours, and the company which owns it has no interest in investing time and money in removing it from the border of the mouth of Laguna Ciega. Over time, swells have rotated the boat on its axis and now represents a threat to the mangroves in the area around it. It also represents an ecological danger from the fuel and lubricants leaking from the boat. The boat could spend years stranded there unless authorities apply pressure by official sanctions against the owners of the boat.
According to a study by the University of Mexico, if the state loses its mangroves all of the coastal cities will suffer even more from devastating floods and without defenses in case of a hurricane. After the recent devastating effects of tsunami’s and other sea storms on world coastal regions, more research is being done to investigate the potential of mangroves’ ability to protect coastal regions from these storms. Little research and documentation has been done previous to the recent tsunami in the Indian Ocean so much of our current information comes from comparing areas with strong mangroves systems and those where they have been depleted. It was found during interviews of people who live where mangrove forests are strong, the trees saved them from the fury of the storms and the associated flooding events versus areas that had been converted to shrimp farms. In more than one area of the world, it has been proven that mangroves offer protection and are able to stay rooted during tropical storms and re-grow leaves shortly after.
Those living part time on the island can help conserve Cozumel mangroves in these ways:
|What can you do to help conserve mangroves in Cozumel ?|
Volunteer to work with local conservation organizations
Participate in the recycling and cleanup efforts of the island
Speak out against developments planned in environmentally sensitive areas
Minimize your environmental impact by following the guidelines for visitors below
Those vacationing in Cozumel for a short time can help conserve mangroves in these ways:
Make NO Wake!
If you are near a mangrove area in a boat, make sure the boat moves slowly so the boat wake will not cause erosion and undermining along the banks. It also disturbs crocodiles and other life that is harbored near the banks. Loud noise, music, loud laughing, whistling or any other noise will disturb birds and wildlife.
Use Alternative Methods to Visit
View mangroves from kayaks or canoe. From this vantage point, one can simply peer down into the mangrove waters to get an idea of these diverse systems in addition to viewing the emergent part of the ecosystem. Snorkelling among mangrove roots can be very rewarding, but it is best done without fins and with great economy of leg movement or fine bottom sediments will be disturbed. These may bring stinging hydroids, detached tentacles and other uncomfortable residues along with it, besides diminishing the visibility considerably. The fine sediments may also interfere with respiration of filter-feeding organisms.
Avoid Walking Amongst Mangroves
Walking too freqently in the perennially waterlogged soils of mangroves and other wetlands causes compaction of the mud as well as smashing any small organisms such as crabs. Soil compaction also results in excess pressure on the roots. But if walking cannot be avoided, try not to step on or damage the soft, tubular roots, which stick up out of the mud. Mangroves use these to breathe.
Don't Litter & Do Pick Up After Others.
Litter and other forms of pollution can make nutrient levels in the mangrove ecosystem too high for mangroves to prosper and may even threaten their survival. By damaging the health of mangroves, careless littering can also affect the species that depend upon the mangroves for habitat, and food... fish, prawns, and crabs, which people love to eat. These animals all depend on mangroves in some way for habitat or food.
Know your Dinner!
Because even your choice of food items may have an implication for mangroves. For example, those luxurious giant tiger prawns now featured prominently on menus in Europe and North America cost the planet many precious mangroves. Because these tiger prawns often come from intensive farming that takes place in clear-cut mangrove areas. Nearly 40% of all mangrove loss worldwide is attributed to prawn farming.
Maintaining mangroves is essentional for Cozumel’s future.
Thank you for doing your part to protect and conserve Cozumel’s mangroves.