Global Change Biol. http://doi.org/chhs (2017)
Rising sea levels endanger coastal ecosystems and communities. Mangroves are salt-tolerant trees that line tropical and subtropical coasts, protecting them from storm surges, reducing flooding, and providing habitat for estuarine animals. They have flourished especially during the last 6,000 years, when sea levels have been stable and as human civilization arose and spread.
Zixiao Guo, of Sun Yat-Sen University, China, and colleagues wondered whether living mangroves are genetically diverse enough to withstand current global change and whether past sea-level changes have influenced this diversity. They surveyed 26 populations of six mangrove species on the Indo-Malayan coast. Genetic diversity was surprisingly low, mirroring levels typical of much smaller populations. The lowest levels were from areas of rapid past sea-level rise, reflecting erosion of diversity as populations shrank. Complementing this spatial assessment, they found similar losses of genetic diversity over time as sea-level rose between 2010 and 2012 in China’s Yalong Bay. To return a historic favour, designing reserves with buffer zones between mangroves and nearby development will give them a chance to colonize inward as sea levels rise again.