Restoring mangroves in the Turks & Caicos Islands

By Eric Salamanca, Scientific Officer, DECR

Photo By Brian Riggs, Curator, National Environmental Centre

The world was shocked when a tsunami struck the coasts of southeast Asia in December 2004. More than 200,000 people were believed to have died as a result of the sea surge and a great deal of property was destroyed, but those who lived along  wooded mangrove coastlines were a little bit luckier because the mangrove forests slowed down the velocity of the rampaging water. This observation affirmed that healthy and well established mature mangrove forests protect coastal communities from surging seas.

In a worldwide estimate, about 50% of the original mangrove forests have been destroyed by man in recent decades. This irresponsible destruction is attributed to ignorance of the forests’ ecological and economic importance. When the mangrove forest is destroyed, the natural sheltering belt against storms, flood waves, flooding and coastal erosion is also gone.

Mangrove ecosystems are comprised of plants, animals and micro-organisms that have adapted to life in the dynamic environment of the tropical inter-tidal zone. The complex and dense root systems encourage sedimentation and development of a mud substrate that enables more mangroves to spread and expand their range.

Mangrove forests develop in areas where high energy waves are absent and sediments accumulate. Tidal flooding largely influences the structure and appearance of mangrove forests. Although most mangrove forests are found submerged in water along the coastline, they can also extend to the flood plain’s outer limits, which are often dry and only occasionally flooded when the water reaches its highest point. Mangroves are adapted for the salty conditions and frequent flooding in the ocean’s tidal range and have ways of dealing with excessive salt.

The flourishing tourism industry in the Turks & Caicos Islands is an indicator of the beginning of an era that can permanently change the environmental and socio-economic landscape. For the construction of new road networks, widening of old access trails and the building of condominiums, hotels, marinas and other amenities for a luxurious life do not come without costs. One of those costs is an environmental one, and the mangrove ecosystem is one of the areas most highly affected. Mangroves, big and small, are indiscriminately damaged by bulldozers and backhoes in the name of progress.

The importance of mangroves

Mangroves offer many benefits to both natural systems and humans, and their removal has several economic consequences.

• Mangroves provide shoreline protection and sediment accretion. They buffer the shoreline from the destructive impact of storms and waves.
• Mangroves trap and bind sediments, thereby reducing coastal turbidity, and help clean the water.
• Mangroves support important trophic pathways by providing a major source of materials for food chains that support many terrestrial and marine organisms.
• Mangroves provide habitat for both marine and terrestrial organisms; homes for both plants and animals.
• Mangroves are nurseries for commercially important fish stocks, replenishing estuarine and coastal fisheries.
• Mangroves are a sink for atmospheric carbon, helping to reduce global CO2 levels and global warming.
• Mangroves capture effluents from terrestrial runoff, providing a buffer for nutrients, heavy metals and other toxicants entering coastal waters.
• Mangroves are an important ecosystem that promotes sustainable eco-tourism.
• More recently, changes in mangroves have been proposed as a means to monitor change in coastal environments as indicators of global warming, climate change, storm effects, sea level change, pollution and sedimentation rates.

Mangrove restoration project

The primary goal of the project is to rehabilitate the degraded mangrove forests in the coastal areas. Although mangrove forest could be restored naturally, this project aims to expedite that natural regeneration. It is not the goal to restore the area to a pristine pre-development condition, but rather to replicate as close as possible the natural conditions that existed before certain areas were disturbed for development projects. Another important component of this project is to increase public awareness about mangrove forests and their role in coastal development and management.

Mangrove habitats

In the Turks & Caicos Islands (TCI), mangrove forests occur as narrow fringes along the most sheltered coasts or in small stands at protected creek mouths. The area of true mangrove forests throughout our Islands is relatively small compared to the total area of wetlands. They occur in areas where they are particularly important for water quality control, shoreline stabilization and as aquatic nurseries.

There are three important species of mangrove in the Turks & Caicos Islands. White Mangrove (Laguncularia racemosa) are found nearest to the dry land and have salt glands at the base of their leaves that exude salt they intake from the water. Black Mangroves (Avicencia germinans), found between the drier land and in the water, have pneumatophores that stick up out of the water like little snorkels. These pneumatophores aid in obtaining oxygen. Black Mangroves exude salt from  the undersides of their leaves. Red Mangroves (Rhizophora mangle) are found directly in the coastal waters. Their unique prop root system stabilizes the tree from wave action — these prop roots extend from the trunk and heavy branches, drop into the water and eventually become part of the trunk system.

Assisted natural regeneration

The restoration strategy is called Assisted Natural Regeneration. Existing mangrove trees are allowed to grow while sparsely growing mangroves and/or totally destroyed/denuded areas will be planted with suitable species of mangroves. There are two basic methods for replanting Red Mangroves along a shoreline.

The encasement method is used to establish mangroves along high-energy shorelines where natural regeneration is difficult or where conventional planting methods are ineffective. The concept of this method is based on individual seedling isolation and a spontaneous adaptation process. By isolating individual propagules (seeds) from the external environment within tubular encasements at the planting site, an artificial environment is created favorable to early plant development: plants are protected from wrack, debris, wind, wave activity and unintentional damage from human interaction. If no protective gadget (like PVC pipes) is installed, the mangrove seedlings will be carried away by the sea waves.

The other, much easier and less expensive method, is to simply insert the propagules into a hole punched in the sand. This works well for very protected shorelines that seldom receive high winds or waves.

Propagation of seedlings in the nursery

To ensure higher percentage survival rate, propagules are raised in a nursery. A mangrove nursery is a place where the environmental conditions are artificially improved to suit the requirements of young seedlings. The best sources of planting materials (propagules) are trees that are already growing in the neighbourhood where the new plantings will take place. In this way, acclimatization of exotic species and/or the introduction of obnoxious pests and diseases are minimized.

Newly planted propagules need protective shade to minimize dehydration due to excessive heat from the sun. Seedlings are watered every other day using fresh water alone or an equal mixture of sea water and fresh water.

It is envisioned that mangrove nurseries will be established on all of the TCI’s inhabited islands, to be managed by the local residents. It is also possible that schools can maintain a nursery in their schoolyard, to enhance children’s awareness. Land developers are also encouraged to embrace this project. It is worth  mentioning that the Turks & Caicos Sporting Club on Ambergris Cay has already approached the DECR for advice on mangrove planting.  We expect other groups to follow and enjoy the benefits of having healthy mangrove forests.

Mangrove restoration is everyone’s responsibility. Widespread participation is welcome and needed, including all important stakeholders: government officials and employees, schoolchildren/students, businesses and private citizens.

How the project will work

The following procedures will be followed:

1. Reconnaissance survey. A team from the DECR and other stakeholders will visit prospective areas for mangrove restoration. The identified site will be prioritized based on importance and urgency for restoration/rehabilitation.
2. Selection of area. The area should be certified by the DECR as a critical site for mangrove restoration and the Planning Department and other stakeholders will be consulted concerning the identification and classification of the area for a mangrove restoration project.
3. Determination of former habitat and/or species. This requires the review of literature (project reports, journals and the like) or interviewing people who are aware of the former vegetation of the proposed planting site.
4. Determination of species to plant. The indigenous mangrove species which can withstand various environmental catastrophes such as flooding, storms and hurricanes will be selected for planting.
5. Production of mangrove seedlings. A mangrove nursery will be established. Seeds (propagules) will be collected and seedlings raised in the nursery. The DECR, in cooperation with some private individuals, has already set up a small demonstration mangrove nursery in order to ascertain the right conditions and methods for local nursery management.
6. Planting of mangroves. Before actual planting will be conducted, the planting sites will be prepared with layout and staking.
7. Monitoring and evaluation. The planted mangrove seedlings/sapling will be monitored regularly to determine their survival rates, growth rate, incidence of pests and diseases, etc. This activity will be spearheaded by the DECR.

The mangroves we will plant

The Red Mangrove is the most abundant species of mangrove in the Turks & Caicos Islands. It is considered the most ecologically significant plant species for marine environments. It is found along sheltered shorelines throughout the Islands. The large, structural reddish roots known as “prop roots” elevate the tree out of the water, giving it the appearance of being on stilts.

This unusual configuration allows Red Mangroves to grow directly in the sea. Stilt roots support the plant above the water, and other roots extend up toward the surface and aid in aeration. The roots and stems of the plant can grow immediately on contact with soil. Red Mangrove is a folk remedy for angina, asthma, boils, diarrhea, dysentery, eye ailments, fever, hemorrhage, inflammation, jaundice, leprosy, sores, sore throat and wounds.

The Black Mangrove has pale, gray-green leaves, shiny above, which are often encrusted with salt. It thrives where Red Mangroves also grow. Its root system consists of long, underground cable roots which produce hundreds of thin, upright pneumatophores on the ground around the tree. These structures have numerous pores which are thought to conduct oxygen to the underground portion of the root system.

A balancing act between infrastructure development and ecological stability is necessary. One of the ways to offset the environmental effects of coastal development is to plant or replant trees like mangroves. Trees make a better environment for humans and animals alike. And it behooves us to look after these important resources for future generations.  Theodore “Teddy” Roosevelt, one of North America’s first true conservationists, put it this way: “The nation behaves well if it treats the natural resources as assets which it must turn over to the next generation increased, and not impaired, in value.”