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roots in brine
“A swampy hinterland bridging terra firma and the sea”

here is something intriguing about mangrove forests. Perhaps it’s the fact that they are neither one thing nor the other, a swampy hinterland bridging terra firma and the sea; or perhaps it’s because they are enigmatic, ecosystems teaming with life and yet inhospitable to mortals. Whatever the reason, mangroves are mysterious, and Muscat is as good a place as any to duck under the boughs and root out their secrets.

Mangroves are coastal trees adapted to estuarine or saline environments. They are present along many tropical coasts, in parts of South America and Africa, throughout Southeast Asia and Australia, and in Oman. In the capital a grove of these plants exists near the beach below the Crowne Plaza Hotel; in fact, the well-heeled surrounding locality takes its name from the Arabic word for mangrove, qurm.

Fodder and fish
The lure of the mangrove
Mangroves are valued for a number of reasons. They provide protection from erosion and wind, and prevent saltwater from surging inland – mangroves protected coasts and settlements from the tsunami-related surges of 2004. The forests have long supplied local populations with medicines, timber, fodder and fish; and they act as nursery grounds for several breeds of fish, including commercial species such as milkfish and sea bream. Mangroves support other creatures including crustaceans, too, and offer shelter to birds – a belt of mangroves near the Oman/UAE border for instance is home to a subspecies of one of the rarest birds in the world, the beautiful white-collared kingfisher.

According to Dr Barry Jupp, a marine ecologist at the Ministry of Environment and Climate Affairs, only one species of mangrove, Avicennia marina, is today found in the sultanate. Pollen records show that another genus, Rhizophora, was present over 5,000 years ago, when the region was less hyper-arid. Today the resilient A. marina grows to around four or five metres in Oman, although in extremely saline habitat growth is stunted. Barry notes that along the Arabian Sea coastline, trees are less stressed by the high temperatures of summer, and that in the fresher lagoons of Salalah and Mahoot Island, trees reach seven or eight metres in height.

“Mangroves have a big problem because they live in salt,” Barry explains. Relatively few plants can tolerate saline conditions, but A. marina is able to survive by excreting salt through glands in its leaves – it’s easy to spot the glitter of salt crystals on both sides of a mangrove leaf. In addition these plants’ root systems act as a filter to the salt. A. marina is easy to spot because it also has aerial roots called pneumatophores, which protrude like blackened fingers through the waterlogged soil round the base of the tree. The pneumatophores aid oxygenation, which is necessary for respiration.

Studying the mangroves
The rise of development
Barry has lived in the sultanate for 18 years, before which he worked in Bangladesh on a project devoted to deep-water rice, which grows on long stalks in ground that floods with water up to two metres deep (conventional paddies are flooded to a depth of about 20cm, he says). Much of his research in Oman focuses on reviewing impact assessments, monitoring the impact of pollution and so on. One study of the mangroves in Qurm suggests that, contrary to prevailing trends elsewhere, tree cover has increased over time, with an eightfold increase in tree cover during the period 1966 to 2006 in the so-called East Channel.

“It appears that the increase in the density of trees is linked to increased development,” he says. More houses and gardens at Qurm Heights mean more irrigation and run-off, which has boosted the mangroves.

Barry also points out that the whole mangrove system is linked upstream with Wadi Adai. “That’s why there were mixed impacts from cyclone Gonu on the mangroves. Certainly there was damage (an estimated 5 per cent loss in sparse areas in the Western Channel) but the huge volumes of freshwater would have helped wash out salty conditions.”

It is ironic that while many acres of mangroves round the world are under threat from development, those in Qurm may perhaps be benefiting from it. Japanese expert Tomoo Shoji, previously with the Ministry, has been boosting the forests by transplanting mangroves in coastal lagoons in Muscat and the Batinah, Sharqiya, Wusta and Dhofar regions. Over 250,000 seedling pots have been planted to cover an area of 85,000 square metres. Long ago mangroves covered great tracts of the country, but even diminished they remain an integral element, coastal oases, in the topographical tapestry that makes up Oman.