Mangroves research growing in importance

Mangrove forests are remarkable, forming the building blocks that make up the foundation of a complex coastal ecosystem. These trees support a variety of life, from bacteria that break down their detritus to the top of the food chain via intricate food webs. Mangroves are important to ecology and socioeconomics, especially in regard to flora and faunal productivity. These trees are one of the main sources of primary production in South Florida’s coastal ecosystems. Mangrove communities are major sinks for land-based nutrients. They act as filters to help maintain water quality and trap sediments, heavy metals, and other pollutants. Mangrove soils are among the most carbon-dense ecosystems in the world. These trees are phenomenal.

Mangroves are inherently resilient. They are adapted to deal with adverse natural conditions. These trees are able to survive in saline and low oxygen environments, and they often take the brunt of storm effects. Unfortunately, the future of mangrove forests is uncertain, given the combined effects of natural and anthropogenic stressors. This includes mangrove systems in our own backyard, like Clam Bay, or the wide expanse of mangroves in Rookery Bay National Estuarine Research Reserve and the Ten Thousand Islands National Wildlife Refuge. Specifically, large contiguous forests have become fragmented and isolated due to surrounding development. Hydrological and topographical alterations associated with development, have caused mangrove die-offs that often required costly intervention to prevent likely forest collapse.

The Conservancy’s biologists have monitored the health of the Clam Bay mangrove system annually since 1999. During this time, this mangrove forest has weathered natural events such as drought, frosts, extended periods of extreme heat and cold, tropical storms, above-average rainfall, Hurricanes Wilma and Irma, and even a meteotsunami. In Florida, mangrove loss due to extreme climatic events is becoming more common. The ability of these mangroves to recover after a storm in the future is questionable. If they cannot recover in between storm events, the outcome becomes bleak.

Recovery takes time.

Mangroves are our silent protectors, standing up to storms, hurricanes, cyclones, and storm surges and they have no choice but to meet these challenges head-on. These trees really proved their worth following Hurricane Irma. The damage to Collier County’s population and associated real estate would have been so much worse without the mangrove systems that absorbed a lot of the storm surge and wind velocity. Unfortunately, human activities have fragmented and stressed mangrove forests. Developments around mangrove forests have boxed the trees in, drastically restricting their ability to migrate inland (coastal squeeze). This causes a cascading effect where these estuarine systems not only lose their ability to adapt to climate-induced changes but lessen their ability to be effective at forming protective barriers to inland communities.

Climate change has the potential of altering the structure, condition, and even location of mangroves worldwide. Sea level rise and the predicted increase in the intensity and frequency of storms could be very problematic. The future status of mangrove systems will largely depend on the health of these forests prior to a storm and their ability to rebound prior to another severe weather event. In the past, if mangrove systems were healthy, they were generally able to accrete enough sediment to adjust and maintain pace with sea level rise.

Northern and inland migration of mangroves into adjacent wetland communities has occurred in Florida since the 1950s, in response to sea-level rise over those decades. Inland mangrove forests have the best chance of surviving in the future, provided their landward migration is not impeded by areas of steep vertical topography or hardened structures such as sea walls, levees, dams, houses, roads, and businesses. Likely, there will be considerable loss of mangrove forests in the coming decades as natural, climatic, and anthropogenic stressors combine with barriers that restrict landward mangrove migration.

Mangroves have proved their worth, ecologically and economically. If solutions are initiated that can alleviate man-made stressors, mangroves might stand a chance. The ability of mangroves to bounce back from the brink of annihilation, given the right set of circumstances, is remarkable. The myriad of factors and processes that shape mangrove forests is very complex. Our understanding of these awesome trees has risen over the last 21 years, but it is largely incomplete.  It is to our benefit to continue to learn the science behind how mangrove systems operate, to be able to predict their long-term viability and thereby their ability to buffer us in the future from severe climate-related events.