By Amy Weiss

Sep 26 2019

Mangroves are a group of plant species that, while often only distantly related, share the ability to live in salty water and grow in the intertidal zones of tropical and subtropical shorelines. Mangrove shrubs and trees support a wide range of ecosystem services: providing a breeding ground and nursery habitat for coastal and marine fish, shoreline protection, and carbon sequestration.¹ Given their shoreline habitat, mangroves have been heavily impacted by coastal development and are facing several climate change-related threats, including sea level rise.¹

Mangroves produce buoyant propagules (fruits, seeds, seedlings) that allow them to travel on ocean currents. These propagules can float on the ocean for several days to several months before establishing themselves in a new place.¹

Some mangroves, like Rhizophora mangle seen above, have seeds that germinate while still attached to the parent plant (called vivipary). It is the seedling itself, not the fruit, that falls from the tree into the water below. In buoyant seawater, a seedling lies flat on the surface and can travel fast. But when it approaches fresher, brackish water—ideal conditions—the seedling turns vertical so its root points downward. After lodging in the mud, the seedling can quickly establish itself.²

The ocean-going propagules of mangroves are one way these species can respond to environmental change; allowing a shift in their distributions.