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article imageOp-Ed: Mangrove forests and salt marshes: Indicators of climate change

By Karen Graham     Jan 2, 2014 in Environment
Salt marshes, mangrove forests and estuaries are found along our ocean coastlines, and perform a necessary and often vital function in maintaining the ecological balance of life. They are nurseries, filtration systems and a protection against erosion.
Without a doubt, no one would question the importance of these ecosystems and their being necessary in keeping the surrounding environment stable. But humankind has a far-reaching hand in the destruction of these valuable systems, and for centuries, we have misused, abused and otherwise been responsible for their demise.
We can see first-hand that along with climate change and global warming, plus man's helping hand, we have created a problem nearing global proportions. Much has been written about the deforestation of many mangrove forests worldwide, resulting in the encroachment of sea water. Additionally, in man's never-ending search for more land to build on, salt marshes have been destroyed.
Estuaries, those areas found near the mouths of rivers, where the saltwater mixes with the fresh waters of the rivers and streams, are also being damaged, and in some areas, irreparably. The largest estuary in the U.S. is the Chesapeake Bay, which eons ago was a valley with a river running through it. Over 150 streams and rivers run into the bay, and its watershed area is immense. The largest estuary in the world is the Gulf of St. Lawrence, a place where all the great lakes flow out to the Atlantic Ocean through the St. Lawrence River.
Deben estuary at high tide.
Deben estuary at high tide.
Anjdrew Hill, U.K.
Mangrove forests and climate change
No less than 35 percent of the world's mangrove forests have been destroyed since 1980. This is a greater amount of destruction than the combined waste of tropical rainforests and coral reefs. Mangrove ecosystems are probably the planets most valuable and necessary of all the ecosystems we have.
Mangrove forest in Key Largo  Florida.
Mangrove forest in Key Largo, Florida.
Lisa Jacobs
They protect low-lying coastal areas from flooding and hurricanes, and their above-ground root systems are shelter and nurseries for many marine animals, while the branches of trees are home to numerous birds and other small animals. But the amazing thing about mangroves is their ability to store atmospheric carbon. They can store 50 percent more atmospheric carbon than tropical rainforests, and this amounts to an ecosystem service valued at over $1.6 trillion a year.
So how has climate change affected the mangrove forests? The answer is two-sided. While the world has suffered the loss of one-third of our mangrove forests due to deforestation, climate change has actually helped in saving mangroves. A study done by the Smithsonian Environmental Research Center and the University of Maryland, published on December 30, used data going back 28 years. The results were published in the National Academy of Sciences.
The research showed that climate change had affected the growth range of mangrove forests in Florida, extending their range to the north. This was not because of warmer temperatures, but fewer freezing periods. From 1984 to 2011, Florida gained over 3,000 acres of new mangrove forest. All the new growth occurred north of Palm Beach County. The mangroves' area doubled between Cape Canaveral National Seashore and St. Augustine, the northernmost part of their territory.
Traditionally, hard freezes will keep mangroves in check, limiting their area of growth. This is calculated on temperatures going below 28.4 degrees F. In the northern parts of Florida, cold snaps are becoming less frequent, while the same cold snaps remain unchanged in southern Florida. But this new growth of the mangroves is encroaching on another vital ecosystem, the salt marsh.
Salt marshes and climate change
Salt marshes, like mangrove forests, play a critical role in protecting shorelines, buffering population areas from flooding, storing atmospheric carbon and providing shelter and nurseries for marine life and wildlife. But not all animals can survive in the harsher ecosystem that is the salt marsh, and neither can salt water loving animals and marine organisms survive in mangrove forests. The long-term affects of the change in ecosystems is already being studied.
So how is climate change affecting our salt marshes? A number of factors can be taken into consideration, like salinity, atmospheric and water temperatures, and sea level rise. Mangroves are also affected by the same changes. We now have governmental protection of our salt marshes in the U.S. but up until the 1980s, salt marshes were covered for mosquito control, or water in them was channeled to dry the land.
Of particular interest to scientists is the increased carbon dioxide concentrations in the atmosphere. So far, the CO2 concentrations have increased from 350 ppm to 370 ppm in the past 20 years, and are expected to double by 2080. At the present time, scientists have no idea of the effects of higher CO2 levels on the food -chain or physiology of salt marshes or their inhabitants.
Salt marsh on the Outer Banks of North Carolina.
Salt marsh on the Outer Banks of North Carolina.
Jim Lawrence
When all is said, the future of our mangrove forests and salt marshes is still unknown. Common sense does tell us that things are already in the process of changing, even if only in a subtle way. Most of us will sit back and say we don't have to worry about what will ultimately happen, because it won't take place in our lifetimes. This is probably true, but at the same time, it is sensible if we do every thing we can to conserve what we do have, rather than continuing to destroy it.
This opinion article was written by an independent writer. The opinions and views expressed herein are those of the author and are not necessarily intended to reflect those of
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