A new study has demonstrated what Palauans have known for millennia – cultivated wetlands, in particular taro (Colocasia esculenta ) fields, can control soil erosion and reduce the impact of watershed discharges on nearshore coral reefs. Taro fields in Palau are designed with embankments that allow a steady flow of water through the field, using the taro plants as a natural sediment trap.
For 2,000 years, the people of Palau, an island nation in western Micronesia, have survived by balancing population growth and development with sustainable agriculture and fishing practices. Communities are experiencing the negative effects of increased coastal development and a movement away from the domestic production of starch in the form of taro.
Increased amounts of runoff from land clearing, agriculture, and development have damaged coral reefs by increasing nutrients from fertilizers, human-derived sewage, sedimentation, and coastal pollution (e.g., from pesticides), as well as decreasing light availability for photosynthesis.
The NCCOS-funded study shows that using taro fields (sediment trapping efficiency of up to 90 percent) in combination with protecting mangrove forests (sediment trapping efficiency of 30 percent) can greatly reduce sediment runoff to coral reefs. An added benefit of reinvigorating fallow taro fields to control runoff is the improvement of the nation’s food security, which presently relies on imported rice for starch. This study is published in the journal Estuarin e, Coastal and Shelf Science.