By Ryann Rossi, PhD student, North Carolina State University
Mangrove ecosystems are one of the most important coastal ecosystems of the Bahamas. Several ecosystem services are provided by mangroves ranging from coastal buffering and carbon sequestration to providing nursery habitat for commercially important marine organisms. Although mangroves are known for being rather resilient, fisherman, scientists, and the local non-governmental organization, Friends of the Environment, have observed die-off of dwarf, red mangrove in an area known as The Marls on Central Abaco.
Recently, scientists from Dr. Craig Layman’s lab at North Carolina State University have begun preliminary surveys of the die-off and are gearing up to implement an experiment this summer. The preliminary surveys of this die-off area revealed high water salinities and what appears to be intense grazing on leaves. Prolonged high salinities in the ground water of mangroves are often a major contributing factor to mangrove death. However, the appearance of heavy grazing on the leaves within the die-off area leads researchers to believe that salinity is not the only factor contributing to the die-off of this mangrove stand. It could be possible that once stressed, mangroves become susceptible to other factors, much like humans being more susceptible to illness when their immune systems are already compromised from a common cold. In this scenario, it is plausible that the mangroves under a high salinity stress may have been more susceptible to herbivory by insects. To test if this is really happening, an experiment will be constructed that will exclude insects in areas of the die-off.
Though salinity and grazing are important potential causes of mangrove death, there are a suite of contributors, many of them stemming from human activity. Direct deforestation of mangroves accounts for the largest loss of mangroves worldwide. As development on coasts and islands like the Bahamas increases, critical mangrove habitats will be impacted. Friends of the Environment is working with the Bahamas National Trust and the Bahamas government to protect the Marls and other key wetland habitat from large scale development. For more information please visit www.friendsoftheenvironment.org.
Ryann Rossi is a Ph.D. Student at North Carolina State University, Layman Lab. Her research interests lie in the ecology of marine coastal ecosystems, primarily those of tropical mangrove systems in the Caribbean. Her research focus is on abiotic and biotic factors resulting in die-off of mangroves, in addition to other food-web interactions within mangrove systems.