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A Mangrove Snorkel


Mangrove Forest Caye
The day is the perfect image of a tropical Caribbean vacation: warm, sunny, and with a light breeze from the northeast. We have just sailed our kayaks to Twin Cays, a mangrove caye split down the middle by a long-forgotten storm. We enter the split, with a low wall of mangrove trees on either side. There is no sign of land: the trees are standing on a jungle of prop roots over shallow water. At the edge of the trees, the bottom drops to a depth of 3m (10ft) - perfect to do some snorkeling.
mangrove snorkeling
We anchor the lead kayak and tie the others in a line. Soon we are in the water with masks, snorkel and fins on and we are exploring the edge of the mangroves. Roots dangle off the edge of the drop-off. They are covered in marine growth: sponges in bright orange and dull grey, thin oysters, and various algae dangle and wave in the slight current. Tiny fish and shrimps hide among the roots as well. This is important habitat for the juveniles of many species.
mangrove coralsI float, perfectly still, staring into the roots. The longer I remain, the more I see. A tiny arrow crab, with impossibly long legs, is picking at a root. A sharp-nosed puffer, his tail curled to one side, is hiding in some sargassoweed. And slowly it comes into focus: a tiny, dark-brown face is peering at me from behind a root. It is a seahorse, and it is clearly hiding from me. I reach behind it and gently scoop it in my hand, calling the others over to see it. It wraps its tail around my finger, hiding in my loosely cupped hands. Everyone comes over and has a look, and it looks at everyone too. I replace the little fish and move on.

There is a most unusual fish that is sometimes found in mangrove channels. It has a long thin snout, a broad body, and its fins are articulated such that the pelvic fins are on the sides of its body and they face forward, like the feet of a land animal. On these feet it walks along the bottom. Well-camouflaged, the short-nosed batfish lies perfectly still on the bottom. You can swim down and touch it: it merely takes a couple of steps and returns to its zen-like stillness.

Here is an image of a baby batfish in a few inches of water:
batfish found in mangrove trees
Mangrove Forests are of major ecological importance in tropical waters. By their strong trunks and extensive system of prop roots they stabilize shorelines and by trapping sediment they expand shorelines and  turn sandbars into new islands. Their roots provide essential habitat for the juveniles of many species of fish, shrimp and other marine life. And the leaf-matter that they drop adds nutrients to an environment that is typically nutrient-poor and low in productivity. In fact, an acre of mangrove forest contributes up to three tons of organic carbon per year to the soil and surrounding waters. Next to seagrass beds, mangrove shores are the most important contributor of organic carbon to the tropical marine environment. And we got to see this unique and highly productive ecosystem up close.

Now for the sail and paddle back to camp, and a chance to open the field guides and put some names to what we saw. Thank you Belize.