LET’S GROW FRESHWATER MANGROVES IN LAKES AND RIVERS
LET’S GROW FRESHWATER MANGROVES IN LAKES AND RIVERS
Many people still believe that mangroves belong only to salty seas and coastal mudflats. That is only half the story. Yes, “true” mangroves are biologically adapted to saline and brackish environments—but in the Philippines, several mangrove species and mangrove associates can grow, survive, and even thrive in freshwater-dominated lakes and rivers. Some of them have been there for centuries. Sadly, many have disappeared quietly, without us even noticing.
The good news is this: as far as we know, none of these species are extinct. That means they can still be brought back—if we decide to do so deliberately.
One famous example is Nilad, the white-flowered mangrove that gave Manila its old name, May-Nilad. Nilad is not technically a freshwater mangrove; it is a true mangrove species (Scyphiphora hydrophyllacea) adapted to coastal and tidal rivers. But history explains the confusion. Nilad once grew abundantly along the Pasig River delta, where freshwater from Laguna Lake mixed with the tides of Manila Bay.
I personally witnessed a specimen of Nilad being presented to the late DENR Secretary Gina Lopez after it was rediscovered upstream in the Pasig River. Since then, Nilad has been revived, propagated, and protected. Today, you can see it in places like the Manila Zoo’s Nilad nursery, the Las Piñas–Parañaque Critical Habitat (LPPCHEA), and even in Baseco, Tondo, where coastal rehabilitation projects have replanted it.
Why should we care about mangroves in rivers and lakes?
Because whether saline or freshwater-tolerant, mangroves do the same ecological magic. Their roots create nurseries for plankton, shrimps, crabs, and fish. Their falling leaves feed microscopic life that fuels entire food chains. They stabilize riverbanks, reduce erosion, filter pollution, and soften the impact of floods and storms. In short, they are living infrastructure.
We already see this in places like the Agusan Marsh, a largely freshwater ecosystem where mangrove associates and riverine species support extraordinary biodiversity. This should inspire us to think bigger.
Why not propagate mangroves and mangrove associates in Lake Taal and Lake Mainit?
Both lakes were once connected to the sea. Taal was a saltwater bay before the 1754 eruption sealed it off. Lake Mainit remains connected to the ocean through the Kalinawan River. These “marine lakes” are perfect candidates for species like Pedada (Sonneratia caseolaris)—one of the most freshwater-tolerant true mangroves—as well as Dungon-late (Heritiera littoralis) and even Nilad, which can survive in freshwater when planted and maintained properly.
Imagine the benefits. In Taal Lake, riverine mangroves could help protect the tawilis, the world’s only freshwater sardine, by restoring natural fish nurseries and filtering water polluted by years of fish cages. In Lake Mainit, mangroves could reduce siltation, protect marshlands, and preserve habitats for native gobies, eels, birds, and insects.
I would even go further. Why not revive Nilad all the way from Laguna Lake, down the Pasig River, and out to Manila Bay? And why stop there? The same approach can be applied to major river systems like the Agusan River and the Cagayan River, where erosion, pollution, and declining fish stocks are already hurting communities.
Mangroves are not just coastal trees. They are bridges between mountains, rivers, lakes, and seas. If we are serious about biodiversity, food security, and climate resilience, then growing mangroves inland is not an odd idea—it is a long-overdue one.
RAMON IKE V. SENERES
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