Mangroves - natural defenders against the sea
By Oscar P. Clarke
Stabroek News
May 31, 2003

Related Links: Articles on seawall
Letters Menu Archival Menu

Amid continuing sea wall breaches, Guyana is on a campaign to re-grow mangroves along its vulnerable ocean defences and is banking on a new project which will point out hotspots where wave action or destruction by humans has eroded the vegetation.

Experts predict a global rise in sea levels of one metre over the next 50-100 years, with Guyana experiencing about 2 metres due to its unique characteristics (these include a mud coast and a large landmass behind a low-lying coast).

According to an Environmental Protection Agency (EPA) document, the country has a coastline of approximately 430 km. The coastal plain extends along the entire coast and lies generally between 0.5 m and 1.0 m below sea level at high tide, which makes the coastal plain, where 90% of the population resides and 75% of the main economic benefits are derived, vulnerable to flooding and erosion.

The mangrove tree once grew lush along the full length of the low-lying coastal plain of Guyana. It was the early Dutch colonisers who came to settle on the coasts by first reclaiming most of the coastal swamps to establish plantation agriculture. They were able to establish a complex system of drainage and irrigation canals, kokers (sluice gates) and sea defence works.

Guyana’s colonial experience and post-colonial modernisation endeavours have transformed the coastal environment. The coastal mangrove swamps have been drained, and mangrove wood extracted and replaced by a complex sea defence system. Research has shown this has created a ‘second nature’ requiring high levels of human inputs, which includes labour and finance, to maintain the structures. The coast is now protected by 69 km of masonry seawalls and 170 km of earthen dams; natural sandbanks protect another 78 km of coast while mangroves protect the other parts.

Guyana’s coast has also shown an unusual characteristic that when accretion is occurring in one part there is almost certainly erosion occurring in another.


Today there are few virtually undisturbed sections of mangrove forest remaining: along the Pomeroon River where the growth is thickest and other small pockets stretching from Charity to Crabwood Creek.

The importance of the mangrove to the country’s wave battered coastal shore is well known as it forms a protective barrier, which breaks the wave action.

In addition its roots provide a nesting ground for coastal bird life and for countless species of fish.

Chief Sea and River Defence Officer, George Howard, told Stabroek News that the mangrove forests prove an invaluable complement to the seawalls.

This is because the mangrove aids in reducing the force of the waves as they reach the shore and crucially they allow for the active build up of the shoreline through accretion.

The vegetation plays a role in stabilising the country’s dynamic coastline, which experiences both accumulation and removal of sediment by huge mud banks that are 30 to 40 km apart and slowly travel up the coast either encouraging erosion or accretion as they pass.

In light of this the government, through a European Union-funded project, is keen on taking measures to ensure that the once thriving seashore forest is revitalised.

The project will see the institutional strengthening of the capacity of the respective agencies responsible for protecting the shore zone to allow them to better manage the entire coastal sector.


One of the methods to be used in the preservation of the mangrove forest is a public awareness campaign targeted at coastal fishermen, farmers and other people living in the coastal areas who will learn about the value of mangroves and other natural or man-made defences.

This will be complemented by effective policing of the sea defences once the legislative measures are strengthened as recommended by the study.

This, according to Howard, would also see drastic reductions in the cost associated with the maintenance of the seashore, which currently expends up to $450,000 per linear metre for riprap structure.

It would cost around $15,000 per linear metre to construct an earthen dam once it is protected or buttressed by a mangrove forest.

Apart from the mangroves, ‘sling mud’, which consists of water with a high concentration of mud also helps to dampen wave energy and this would normally occur for a few months after which it is pulled away as part of the natural process associated with the migratory mud banks.

It is then that larger waves can uproot the mangrove trees as the constant ebb and flow leaves the roots exposed resulting in their easy dislocation.

It is exactly this process that is occurring along the West Coast Berbice foreshore and Howard noted that it is difficult to stop.

However, once the sea begins to deposit matter on the shore again there is usually a regeneration of the mangroves.

Stabroek News on a recent visit to the WCB foreshore and Belladrum and Onverwagt noted the massive erosion of the shoreline leading to the uprooting of the existing mangrove forest.


At one point the wave action had begun to attack the existing earthen embankment resulting in serious erosion necessitating urgent remedial attention to avert inland flooding.

However it was only approximately a year ago when on a previous visit, that there was a build up of matter on the shore, which was affecting drainage in the area.

A similar situation is said to have led to the current breaches at Profit/Foulis where the earthen dam buttressed by the once existing mangrove forest was helplessly eroded by the fierce wave action striking that coastal zone.

On both sides of that eroded shore there was evidence of once vibrant mangrove growth for several miles along the coastline.

Similar destruction of the mangrove forest was sighted along the foreshore between the East Coast Demerara villages of Mon Repos to Lusignan where almost two kilometres of sea defence had to be buttressed by bouldered revetment.

This area, which once featured a cremation site similar to one presently existing on the Ruimzeight foreshore amongst the mangrove, was systematically destroyed by a combination of wave action and human mismanagement.

This situation also exists at Ruimzeight where there is clear evidence of the removal of a portion of the mangroves to facilitate the erection of a sea defence wall while some of the wood has been used by the fishermen to tie up their nets and vessels as well as to make traps for fish and crabs.

The bark is also used in tanning leather, in the charcoal industry and in making burnt earth for rural roadways.


The mangrove forest has the capacity to develop strong growth within a 15-year span as shown on the West Coast Demerara at Harlem where in the mid-1980s a severe sea defence threat was drastically lessened with the growth of the forest.

Howard recalled that with the dredging of the Demerara River the deposits thrown on the western back were transported by tides to the shores of that area leading to the rejuvenation of the forest. It continues to act as a buffer for the existing sea defence.

The EU study, which targeted the Essequibo Islands, recognised that unpopulated islands like Bird Island actually have an expanding landmass, which is visible by its sand build up on the shores.

Experts say this is due to the preservation of the natural vegetation which offers that island a natural source of protection while promoting growth in the landmass.

Leguan on the other hand, which has had a great deal of its natural protection removed, is vulnerable to the elements of the river which during extreme high tides has caused massive flooding.

Communications Consultant in the Ministry of Public Works, Ajay Baksh reiterated the ministry’s commitment to the protection of the natural defences. According to Baksh, the ministry is 100% behind the protection of the mangrove as studies have shown that with its preservation the likelihood of threats from the sea would be greatly reduced.

The ministry, he further said, would continue to work towards having persons educated as to the importance of the mangrove although they acknowledge that some social and economic conditions help to influence the activities of some communities with respect to the forest.


The Guyana Forestry Commission (GFC) as part of its mandate to protect the country’s forest reserves is currently involved in several projects to effectively manage the precious resource.

The studies conclude that the removal of mangroves for fuel wood from the Essequibo River to the Corentyne has not only exposed lengths of coastline to erosion but also degraded these ecosystems, limiting their ability to act as nurseries for fish species (an estimated 75 percent of fish caught commercially spend some time in the mangroves or are dependent on food chains which can be traced back to these coastal forests).

Mangrove plants and sediments have also been shown to absorb pollution, including heavy metals.

Mangroves along the Northwest coast are still largely intact. The GFC was expected to carry out an evaluation of the mangrove resource and plans for its protection and management.

Meanwhile a lot of quick profit enterprises, which degrade coastal resources, for example beach sand and seashell removal is viewed as a lack of understanding of the economic contribution of coastal resources to society.

There is also the issue of over-harvesting of mangrove vegetation and consequential habitat destruction while threatening the bio-diversity of other organisms.

There are currently three types of identifiable mangrove forests these being the black, which is the most widespread on the coast, the red and the white varieties.

With the assistance of the EU-funded project it is anticipated that with the collection of data there would be the ability to predict likely trouble spots. This would be facilitated by the development of models and a database to identify areas of sediment transport and seabed evolution as part of a wider study.

Rangers police the existing sections of mangrove forest with residents acting as backup to ensure their integrity.

As Guyana faces rising sea levels in the coming decades, it is ironic that centuries after mangroves were removed for the establishment of key parts of the coast, it should now be returning to play its part as nature’s best sea defence.

Site Meter