Sink, shift, or sprout?
Restoring mangroves in vulnerable coastal settlements

Timbulsloko Village seems to be sinking. At high tide, the ocean enters people’s houses, and licks at their floors and furniture. During storm surges and heavy rains, the sea takes bigger bites out of homes and pathways. The road through town, carefully paved with concrete, is sodden and impassable.

To adapt to the rising seas, people have rebuilt their houses on poles, and created meter-high walkways on stilts so they can move around without needing to wade or swim. They wheel their motorbikes to higher ground at the edge of town, and park their boats beside their homes instead.

This settlement in Demak Regency – on the northern coastline of Central Java in Indonesia – used to be a rice-growing area, well-known for its fertile river-delta soils. A wide green belt of mangroves protected the village from the waves and tides, as well as providing a reliable food source and habitat for fish and other marine animals. But in recent decades, lured by quick profits, villagers felled the trees along the shoreline and converted their rice fields to fishponds, where they began to farm prawns and milkfish [Chanidae chanos]. 

Since then, the village has been hard hit by erosion and flooding, and now sits below sea level. According to local fishers, catches have also decreased significantly as the mangrove habitat has disappeared, compromising livelihoods.

In response, some residents have cut their losses and gone to live elsewhere.

“In general, if mangroves are thriving, they are able to trap the sediment and break up the wave energy, so typically the soils keep on increasing – and we get good carbon storage in the process,” said Bhomia. Globally, mangroves host around 1.6 percent of tropical forests’ biomass while occupying only 0.6 percent of their area, and they can put away four times the amount of carbon as tropical rainforests. Restoring and conserving the world’s mangroves could protect 18 million people from coastal flooding, and boost the productivity of the planet’s fisheries.

To that end, the researchers are also studying the effects of mangrove presence on community health and nutrition, including food security, income, macro- and micro-nutrient intake and dietary diversity. Mangrove ecosystems offer a wide range of services for the people that live nearby, including fisheries – and fish nurseries – that provide key sources of protein and micronutrients, as well as a critical income opportunity for many community members.

Residents also use the mangrove forests for timber, fuelwood, medicinal purposes, crafts, and more. 

The leaves and fruit of the mangrove trees can be eaten, too, and some community members dry and grind it into flour, which can then be made into a range of processed products.

For each of the three research sites, the researchers are undertaking a coastal vulnerability assessment, which examines three dimensions: exposure to stresses, associated sensitivity, and adaptive capacity. The assessment takes into account a wide range of variables, including geomorphology, shoreline change, the coastal slope, the tidal range, mean sea level, wave height, stakeholder engagement and community awareness.

They also carry out socio-economic surveys, which assess the contribution of mangroves to the livelihoods, food security and nutrition of the local communities. This includes consideration on the gender dynamics of these issues, which can vary from place to place: for instance, in Banyuwangi, women usually collect shellfish (such as oysters and clams), while in Demak, fishing is mostly done by men, and women are generally involved in post-catch activities such as sorting, selling, and processing. In both areas, mothers are usually responsible for managing food budgets and deciding what foods are to be bought.