The Mud of the Mangroves

A boardwalk over the mud leads through the many species of mangroves surrounding Tambobo Bay

I suppose the smell hits you first. As you walk into a mangrove forest, the deep, gaseous, almost sulfuric smell of the swamp tells you where you are. There’s no point wearing shoes here, and no one does. The dense, rich, pitch black mud will suction-stick onto anything you’re wearing, so you’re better off barefoot. For all the beauty of the trees, the alien fascination of their tangled and knobbed root systems, the clicks and pops that seem to converge on you from everywhere at once and nowhere in particular, it’s the mud of the mangroves that feels most characteristic of this unique ecosystem.

Salt-tolerant trees growing in the swampy, fluctuating intertidal zone of tropical coastlines, mangrove forests muddle our best efforts at distinguishing land from sea. In Negros, where I’m working on community-based conservation this summer, gnarled roots make chaos of the forest floor as small inlets pass between thickets to create narrow pathways under the waxy, green leaves. Tree roots filter water to trap sediments and pollutants that would otherwise choke the coral offshore. These roots provide homes for mollusks, crabs, prawns, and young reef fish hiding from predators; hold the soil together to prevent coastal erosion; and serve as a buffer to protect human communities against heavy waves, typhoons, and storm surge flooding.

 

An old Sonerratia alba (locally known as pagatpat) in the Siit mangrove forest. The cones sticking out of the mud are pneumatophores that provide this tree’s roots with oxygen.

And then there’s the mud. The yielding, pungent mud of these liminal forests, pocked with bumps and holes, littered with yellowed leaves and rotting fruit, hosts an outrageously productive ecosystem. Knobbed pneumatophores creep out of the muck like fingers and toes, sucking oxygen for waterlogged tree roots. Foot-long mangrove lobsters dig fastidiously, gouging burrows that give the forest floor lumps and mounds. Mudcrabs scurry from one hole to the next, up branches and between canopied Rhizophora roots. And people slush by it all, gleaning crabs and oysters for dinner, casting nets for shrimp and fish, harvesting carbon-rich branches for firewood and termite-resistant trunks for housebuilding, and stripping bark to flavor coconut wine.

For some, mangrove mud is more valuable without the forest. The dense substrate, flat topography, and tidal influx make this land ideal for outdoor aquaculture. In Negros, some 60% of mangrove habitat has been converted to milkfish ponds. And while aquaculture in the Philippines brought the hope of small-scale livelihood development, in practice the industry has been controlled by the few with sufficient capital to maintain ponds. In Negros, the commons have become private property, and the public goods described above- flood protection, fishery stocking, subsistence harvest of food and timber- all replaced by private profit. The socio-economic outcomes are ambivalent at best, and the environmental ones are unequivocally poor.

The canopied roots of these Rhizophora mangroves provide habitat for important fishery and subsistence species. These trees are part of a reforestation effort to fill in an abandoned fish pond in Pulo, Negros Oriental.

Conservationists, too, hope to profit from mangrove mud. In Negros, where nearly a quarter of fishponds lie abandoned and ripe for reforestation, organizations like Marine Conservation Philippines see potential for “Blue Carbon” projects linking community-based restoration to carbon offset markets. Both forests and wetlands, these ecosystems sequester atmospheric carbon in double-time, simultaneously through tree growth and the decay, filtration, and trapping process that creates carbon-rich mud. In Siit, where the local Women’s Association has been replanting mangroves for decades, MCP hopes to help quantify and sell carbon credits so the group can earn income for its conservation efforts. Will this be feasible? Will profits be equitably distributed? Will payments change the group’s relationship to previously voluntary work? These questions remain unclear, and MCP is navigating them carefully.  What is clear, however, is the opportunity that mangroves offer for balanced human-environment relationships. It’s an opportunity clear as mud.

Members of the Siit Women’s Association PAPSIMCO teach the author how to transplant the mangrove locally known as bungalod (Avicennia marina) in their mangrove reforestation nursery.

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