Mangrove forests can be found where the land meets the sea, supporting a wealth of tropical life. But in many parts of the world they are disappearing and preserving them takes dedication.
Stepping through the mud, Abdou Karim Sall introduces the stands of trees as though we're strolling through a community allotment. "These are from this year, those are from 2014. Those over there, they were planted in 2013," he says, waving his arm to indicate which stand is which.
We are in the mangroves in the backwaters of Joal, a town in Senegal about two hours' drive south of the capital Dakar.
Joal is best known as a fishing town. Each afternoon, open boats called pirogues arrive at its beach to offload their catches of herring-like sardinella and other sea fish. They've come from several kilometres offshore. The beach comes alive with activity - porters carrying heavy crates of silvery fish up the shore, horses and carts splashing through the shallows, people buying and selling.
But behind Joal, away from the hustle and bustle and commerce, there is a quieter world - the backwaters and their mangroves. To experience this estuarine world properly requires a shallow-draft boat, a skilled boatman and the right tides - and, of course, a knowledgeable guide. On the morning of our visit, the sun is already high, it's approaching low tide and our guide is Abdou Karim Sall.
Originally a fisherman, Abdou Karim stills goes to sea but his main occupation is now on land. For much of the time, he campaigns on behalf of his fellow fishermen for a sustainable future for the offshore fishery. But he also exudes a zeal for environmental protection, which extends to the health of the local mangroves. These tangled trees, which grow in shallow saltwater and line the muddy channels of the backwaters, are not towering or majestic, but they are crucial as a nursery area for fish and as a habitat for oysters and other shellfish.
Over the years, some parts of the mangrove forest have suffered. Droughts drove up the water's salinity, which led to mangrove dieback over large areas. More recently, mangrove trees in some parts have been harvested for fuel wood, to heat cooking pots at home and also to smoke the sardinella on a semi-industrial scale at a site nearby. Climate change may also be having an effect.
Abdou Karim's response has been to jump to the trees' assistance, by mimicking natural processes. Mangrove trees produce a seed called a propagule. When it's mature, this spear-like, 15cm-long (6in) structure drops off the parent plant into the sea to be carried around by the tides. A few of these hardy seeds will settle upright in the mud at low tide, and then grow. Abdou Karim wants more of them to find their feet in the estuary.
As we walk across the mud, feeling it slip between our toes, Abdou Karim snaps off propagules and gathers them in his hand - like a bunch of asparagus spears. He does this almost automatically, but he is a man with intent.
In front of us in the glistening mud, on the edge of more mature stands, grow baby mangrove trees about knee-high - slender stems poking out of the grey ooze, each with a neat little crown of waxy leaves. They look as if they've established themselves naturally, but that is an illusion. "These are from last year," he says proudly.
But establishing mangroves needs many hands. Abdou Karim explains that much of the planting has been done by local women, fisherfolk and school children. The children work for pocket money during the holidays, squads of willing hands sticking propagules into the mud in neat rows. It is the simplest of tasks, but the impressive results are there to see for anyone who takes the trip into the watery world of wide horizons and mudflats behind Joal.
Now it is our turn, no pocket money for us, but a keen sense of satisfaction as we each plant propagules a metre-or-so apart in a straight line drawn by Abdou Karim with a stick dragged across the mud.
Returning to our boat, after a couple of hours, involves some considerable wading. Mangrove leaves drift by us in the tidal currents. Small fish skitter across the water's surface, pursued no doubt by something bigger underneath. And egrets hunt in the shallows. This habitat is essential for the wellbeing of many fisherfolk at Joal - not so much those landing the sardinella, but the ones using small nets in the estuarine waters or harvesting the shellfish encrusting the mangrove trees' roots.
Abdou Karim is not alone in protecting the mangroves, but his is one of just a handful of voices arguing for this goal. The backwaters may be a quieter, softer world than the daily spectacle of many tonnes of silvery sardinella being landed on a beach. But the committed work of people like Abdou Karim will help ensure that the mangroves' quiet, nurturing role in the natural affairs of Joal has a clear and prominent voice in the town.
Why mangroves matter
- Mangroves are home to a large variety of fish, crab, shrimp, and mollusc species and serve as nurseries for many coral reef fish.
- Mangrove wood is resistant to rot and insects, making it extremely valuable - many coastal and indigenous communities rely on it for construction and fuel
- The dense root systems of mangrove forests trap sediment flowing off the land, helping to prevent erosion and protect coral reefs from being smothered
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