What Is a Mangrove?

A mangrove commonly refers to two different things: a tidal swamp ecosystem found in tropical deltas, estuaries, lagoons or islands, and the characteristic tree species populating this ecosystem. Mangrove trees have developed unique adaptations to the harsh conditions of coastal environments. They survive high amounts of salinity either by excreting salt through their leaves, or simply by safely keeping it within their tissues. Their root systems are shallow and partly exposed to the air, which allows them to breathe in an environment that’s frequently flooded and low in oxygen. Mangrove swamps are unique ecological communities that link freshwater and oceanic ecosystems and host a rich diversity of animal species.

Because of their sensitivity to the cold, mangroves are restricted to the tropics and subtropics. They are primarily found in two areas: the Indo West Pacific (58 species), and the Atlantic East Pacific (12 species) along coastlines of Central America and Mexico. EcoLogic focuses its work in this region, which is home to the red mangrove, the black mangrove, the white mangrove and the buttonwood, and is making great strides in terms of sustainability. For example, EcoLogic partners with local fishing villages in the Sarstún river region of Belize and Guatemala to implement positive changes in waste management, water source protection and reforestation.

Biology of mangrove ecosystems
Mangrove forests are an ecosystem of incredible biological diversity comprising hundreds of algae, mollusk, crustacean, fish, insect, reptile, bird, and mammal species. Saltwater crocodiles, pelicans, egrets, spoonbills, flying foxes and monkeys are all residents of mangroves, just to name a few. The trees’ intricate network of roots provides a shelter for many oceanic and freshwater species, and the forest is a food source for many types of organisms as well. While certain species spend their entire life span in this ecosystem, numerous fish species use the shelter of the mangrove as a nursing ground before heading to the open ocean, to the extent that one third of all marine species were born and raised in mangrove forests around the world. As a result, the mangroves’ well being is central to the health of many more ecosystems.

Human uses
The diverse products and services generated by mangroves have traditional as well as commercial uses. The most direct product of a mangrove tree is its wood, which is used either as fuel or as a construction material. Other parts of the tree are also harvested to manufacture corks and floats, dyes, soap alternatives, synthetic fibers and cosmetics, and even food in the form of fruit, honey, vinegar, salt, or cooking oil. Furthermore, several mangrove species have significant medicinal properties. In addition to this wealth of different uses, mangrove ecosystems are well known for their important role in fisheries health. By providing a safe nursing ground for a wide range of fish larvae, they enhance the survival rate of these species in their early life stages.

Relevance to climate change
RS2089_DSC_0387-hprIn addition to the important biological functions they perform, mangroves also provide crucial ecosystem services to people. Because of their high capacity to recover from natural disasters, mangroves are particularly valuable in the face of increasingly frequent and violent tropical storms and hurricanes. By offering an obstacle to wind and waves, they significantly decrease the intensity of the storm while reducing its human and material toll. For example, a mangrove section of 30 trees per 0.01 hectare and with a width of 100 m can reduce the destructive force of a tsunami by up to 90%. Their roots also play in important role in trapping sediments and stabilizing shorelines facing increased erosion pressures.

Besides their role in shoreline protection, mangroves constitute a valuable tool in the fight against climate change. When a tree grows, it stores carbon in its biomass, thus decreasing the amount of carbon dioxide in the atmosphere. Mangroves perform this carbon storage mechanism particularly well, as they can store up to five times more carbon than an equal area of rainforest. These efficient carbon sinks are becoming increasingly relevant in the light of worsening climate change.

Threats to mangroves and solutions
Although very complex and resilient to natural disturbances, mangrove ecosystems worldwide are endangered by human activity and are lost at a greater rate than inland tropical forests. Sea level rise and sedimentation off-balance the delicate adaptations of a mangrove tree to its environment, inhibiting its development or killing it off. Human-induced thermal, agrochemical, nutrient, heavy metal and oil-spill pollution also seriously impact this fragile ecosystem while deforestation and coastal development are one of its largest threats. Particularly, development pressures caused by a growing population and intensified shrimp farming activities cause large amounts of mangrove destruction.

It is crucial that steps be taken to conserve ecosystems of such biological and climate change mitigation value, and there are several ways to stop the global decline of mangrove forests. Governments can put policies and regulations in place to halt deforestation and promote the conservation and restoration of mangroves. Also, mangroves can be included in market-based mechanisms such as REDD (Reducing Emissions from Deforestation and Forest Degradation) so that they can be used as a source of credits for global carbon markets.