Florida's Wetlands and Mangroves
IMPORTANCE OF WETLANDS AND “BLUE CARBON”Although they receive much less attention than the world’s tropical rainforests, wetlands are far more important for mitigating climate change. Whereas carbon is released from forest ecosystems through decomposition and fires almost at the same rate it is stored, wetlands can store hundreds, or even thousands, of years’ worth of carbon in their underlying soils if they are not disturbed. The carbon stored in coastal and marine ecosystems is known as “blue carbon.”
The chart below, from the International Union for the Conservation of Nature (IUCN), shows estimates of carbon stored in the top 3 feet of soil in 4 types of marine and coastal habitats compared to tropical forests. Keep in mind that rainforest soils are extremely thin, so this figure likely accounts for the bulk of the carbon stores. Wetlands, on the other hand, might have 10 or 20 feet of carbon-rich soil under the living roots.
In addition to carbon storage, wetlands help prevent floods by slowing the movement of water and allowing it to soak into the earth. They are critical nurseries for fish. The plants that grow in wetlands filter pollutants like fertilizers before they make it into rivers, lakes and oceans. They protect fragile coastlines by moderating storm surges from the ocean. And 40% of the world’s animal species rely on wetlands during part, or all, of their lifecycles. Oh, and more than one billion people rely on wetlands for their livelihood. Wetlands are important.
Perhaps because they are so overlooked, wetlands are disappearing at three times the rate of the world’s forests. In the first ever comprehensive study on the global status of wetlands, completed in 2018, the global Ramsar Convention on Wetlands determined that 35% of the world’s wetlands were lost between 1970 and 2015 and 87% have been lost since the year 1700. We continue to lose approximately 3% of our wetlands every year, although many more protections are in place to slow the degradation.
FLORIDA’S MANGROVESAlthough much of Florida’s coastline has been tamed to build cities, ports and strips of hotels, nearly half a million acres of mangrove forests still remain, and your adventure with Nat Hab will immerse you in some of the largest intact mangrove ecosystems in North America.
Mangroves are small trees that live in saltwater and brackish water (mixed salt and fresh), rooted in the muck that is made up of centuries of the acidic accumulation of dead leaves and roots. Most plants would not be able to survive in these conditions, but each of the 50 species of mangrove around the world has found a way to thrive and outcompete any potential plant competitors.
Florida is home to three species of mangroves. One species, the red mangrove, is a “salt excluder,” and the black and white mangroves are each “salt secreters.”
The red mangrove (Rhizophora mangle) typically grows along the water's edge and is easily identified by its tangled, reddish roots called "prop-roots" that sometimes drop down from the branches into the water. These roots make the trees appear to be standing or walking on the surface, and they are sometimes called “walking trees.” Red mangroves primaily use “ultrafiltration” as a strategy to survive in salt or brackish water. This means that the roots prevent most salt from ever being taken up into the body of the mangrove. However, some salt does still make it into the xylem (about ten times the amount of a typical plant), which then makes its way out to the leaves to be secreted or dropped when the leaves naturally die.
The black mangrove (Avicennia germinans) is usually found at higher elevations, upland from the red mangrove. The black mangrove can be identified by numerous finger-like projections, called pneumatophores, that protrude from the soil around the tree's trunk. The black mangrove, similar to the white mangrove, has glands on the surface of its leaves to secrete the salts that are taken up from the water. The salt concentration in a white or black mangrove is ten times higher than in a red mangrove.
The white mangrove (Laguncularia racemosa) is found farthest upland of Florida’s three mangrove species although, to be fair, we are talking about a miniscule topographical gradient here. To distinguish the white mangrove from the other two species, look at the leaves. They are elliptical, light yellow-green and have two salt glands at the base of the leaf near the stem. If you get a chance, try licking the leaves to taste the pure salt that has made its way through the plant. The white mangrove has no prop roots or pneumatophores.
Although the world’s wetlands are endangered habitats, we can make the decision to protect them and, in so doing, protect ourselves. Countries around the world can commit to eliminating draining and development of wetlands, and marine reserves can be created for these critical habitats. In the Everglades, however, there is one threat that we might be too late to control.
UNWELCOME VISITORSAlthough their elusive habits and excellent camouflage make it nearly impossible to see a Burmese python in the Everglades, this invasive species has wreaked havoc on the populations of small mammals in the region.
They are believed to have been first introduced to the wetlands in the 1980s by regretful owners who might not have realized their exotic pet snake would grow to be up to 20 feet long and weigh 200 pounds. These few individual snakes then experienced a population explosion when Hurricane Andrew destroyed a python breeding facility in 1992, releasing thousands of snakes into the national park.
The warm, wet ecosystem of the Everglades is similar to the snakes’ native habitats in Southeast Asia except for one significant missing link – predators. A single female python can lay 50 – 100 eggs per year, and nothing eats the eggs or the adult snakes. With nothing to check their expansion, their current population is believed to be in the tens of thousands.
The U.S. Geological Survey estimates that Burmese pythons have reduced the local populations of raccoons and opossums by as much as 99%, bobcats by 88% and they have completely eliminated some species of rabbits and foxes. They are also able to eat small deer and even alligators, although gators are the one species in the Everglades that has equal odds of prevailing over the python.
Wildlife officials in Florida train and pay professional snake hunters to help reduce the population, and they can be hunted on private land any time of year without a license. The snakes are so difficult to find, however, that these hunters only capture a couple thousand snakes per year, which is an extremely small percentage of the overall population and is unlikely to significantly reduce their impact.
In an effort to find new ways to eradicate pythons from the Everglades, the Florida Fish and Wildlife Conservation Commission began training two dogs to track down pythons by scent, and then stay 3 feet away from the snakes for their own safety while they alert their handlers who make the capture. In December of 2020, they had their first success when one of these dogs, named Truman, led his handlers to an 8-foot python.
Clearly these two dogs have their work cut out for them and many more will need to be trained. And hunters will need to continue their risky endeavors to reduce python numbers as well. It is likely that the Burmese python will never be eradicated from the Everglades. It would be much better if these non-native snakes had never been imported to the United States. While it is too late to undo the impact to the Everglades, it can be a lesson to us all to be thoughtful and ethical when we are choosing a family pet in the future.