Navotas wetlands: Pollution, reclamation threaten ‘nature’s kidneys’ 

The mudflats in Navotas City are not exactly a tourist-y spot, but rare migratory birds love it. It also helps maintain water and air quality in the area.

MANILA, Philippines – Across a fisherfolk village in Barangay Tanza 1 in Navotas City, you’ll come across the muddy and mushy tidal lands which appear only during the low tide.

Beyond these mudflats is the the Tanza Marine Tree Park, one of the major wetlands in Metro Manila. Locally known as Sitio Pulo, the tree park spans a 26-hectare beachfront and houses the oldest mangrove trees in Metro Manila.

With grayish-brown sand, these areas are not what one could classify as tourist-y. They present themselves as some sort of wasteland. 

But these mudflats and mangrove areas are teeming with marine life and serve as a silent protector of their community. 

Nature’s kidneys

“The perception that wetlands are wastelands continues to hinder humans from reducing pollution and pursuing activities that are harmful to wetland ecosystems and biodiversity,” said Annadel Cabanban of Wetlands International Philippines.

If tropical rainforests are dubbed as “lungs of the earth,” wetlands are called its kidneys. 

These misunderstood ecosystems perform physical, biological, and chemical processes that can treat wastewater. They slow down the flow of water, allowing the soil and the sediment particles to settle.

“Wetlands improve water and air quality. Just as kidneys filter dirt from the bloodstream, wetlands filter pollution from the water and capture carbon in the atmosphere. They act as natural filters and help in maintaining water quality by trapping sediments and pollutants from upstream sources,” Cabanban said. 

“They regulate the cycling of essential nutrients such as nitrogen and phosphorus by maintaining only optimum levels to reach the marine environment,” she said. 

In excess quantities, nitrogen and phosphorus are harmful for water bodies as they stimulate the growth of algae. Increased growth of algae decreases dissolved oxygen and contributes to problems like fish kills. 

These unique ecosystems also serve as nature-based solutions towards climate change and the first lines of coastal protection against disasters. 

“Coastal wetlands protect coastal communities from flooding, erosion, and the impact of storms. Wetlands protect coastal cities from the impact of strong wind and waves. They also act as water storage areas in times of heavy rainfall, thereby mitigating flooding,” Cabanban said. 

For a coastal and flood-prone community like Navotas, Sitio Pulo and its mangroves are on the frontlines of their defense against disasters like storm surges. 

A study by the Nature Conservancy and Wetlands International found that mangroves “reduce storm surge water levels by slowing the flow of water and reducing surface waves.” 

“Measured rates of storm surge reduction through mangroves range from 5 to 50 centimeters water level reduction per kilometer of mangrove width. In addition, surface wind waves are expected to be reduced by more than 75% over one kilometer of mangroves,” the researchers explained.

Bird haven

Navotas’ wetlands serve also as habitat for shellfish species, such as river mussels, pen shells, barnacles, and saltwater clams. These serve as locals’ source of food and livelihood. 

Data from the Department of Environment and Natural Resources (DENR) and Wild Birds of the Philippines said more than 70 migratory bird species are said to be found in the area. 

The mudflats are considered as migratory birds’ pit stops, where they rest and feed before continuing their journey to their destinations.

Jon Villasper, a geographer and one of the founders of Wild Birds Club of the Philippines, is a frequent visitor of Navotas due to these birds.

“I’ve been to other parts of Manila Bay. I’ve seen birds, I’ve seen flocks of birds, but not of the same level in Navotas. The longer you look at the area, the more frequent you visit the area, you discover more species or new records [of migratory birds],” he said. 

In 2021, rare migratory bird Black-faced spoonbill was sighted at the Tanza Marine Tree Park, feeding and resting with other species in the wetland area. 

“It (mudflats) serves as a feeding ground for a lot of organisms, particularly birds and other crustaceans,” Villasper explained. 

Under siege 

As part of the Manila Bay coastline, these wetlands serve as catchment areas for the garbage that usually end up in water bodies. 

Fortunately, the marine tree park is protected by the DENR and is a popular site for coastal cleanups. Every Sunday, volunteers and barangay workers visit the mangrove area to pick up trash and plastics which tangle with the mangroves’ roots.

But, unlike the marine tree park, the community’s mudflats are not locally protected by ordinance.

“We forget the fact that mangroves are just resting areas. There’s no food for animals there, the food is in the mudflats. So if you neglect or remove the mudflats, you will end up with a mangrove area with no biodiversity, dead and silent,” Villasper said. 

He also said that removing these mudflats may also mean the disappearance of the migratory birds in the area. As for the locals, mudflats’ conversion would also mean losing one of their coastal defenses. 

“Sa community, ‘yung sinasabi natin sa mangroves na tidal wave, tsunami prevention, that’s also true for mudflats. Kasi ang mudflats, by the term itself, flat ‘yan. Halos flat. And an extensive mudflat would allow for the dissipation of energy ng tsunami, instead of the tsunami hitting you right there and then, the mudflats slow it down. Hindi lang mangroves,” he said.

(In the community, when we talk about mangroves providing tidal wave and tsunami prevention, that’s also true for mudflats. The term “mudflats” itself suggests that they are flat — almost completely flat. An extensive mudflat can help dissipate the energy of a tsunami. Instead of the tsunami hitting you directly, the mudflats slow it down. It’s not just the mangroves.) 

The mudflats are threatened not just by waste pollution but also by development initiatives like the Navotas Coastal Bay reclamation project. 

Bigger picture

The situation in Sitio Pulo and the Navotas City’s mudflats reflect a bigger global problem.

According to the United Nations Environment Program, 85% of wetlands present in the 1700s were lost by the 2000s after being converted for “development, farming, and other productive uses.” 

A 2018 report by the Convention on Wetlands said that these ecosystems are vanishing three times faster than forests amid urbanization and shifts on land use, with the loss rate increasing every year since 2000. 

Non-profit environmental conservation organizations like Wetlands International Philippines have long been calling the attention of governments, both at the local and national levels, to establish stronger conservation efforts. 

According to Cabanban, this can be done through enacting policies that would promote the wise use or sustainable use of wetlands. 

“Value wetlands as critical ecosystems for human wellbeing. Please follow proper management laws, participate in or conduct youth-led cleanup activities and voice support for bills such as the Integrated Coastal Management Bill, National Coastal Greenbelt bill, among others, and adopt environmentally-friendly practices to reduce pollution and minimize impacts on wetlands,” she said.

Similarly, Villasper emphasized local communities’ role.

“Take pride in what you have, and enjoy it. Let’s enjoy the environment, let’s enjoy biodiversity. Because, if you enjoy it, there’s a bigger chance that the community will protect it more. Let’s learn to appreciate,” Villasper said. — Shane del Rosario/Rappler.com

Shane del Rosario is a BS Development Communication student at the University of the Philippines Los Baños. This article was written as part of the requirements for DEVC 128 (Science Communication for Development), and was vetted by Rappler editors before publication.