In 1998, during the post-Hurricane Marilyn major renovation of Coral World, we created a man-made red mangrove lagoon with fewer than 50 small seedlings. Today, these small protected seedlings have grown into a dense mat of trees. In fact, the mat became so dense that at one point we decided we had to try to relocate some of the trees or the walls of the lagoon would burst. Now the upper part of the lagoon is home to our Southern Stingrays.
Our goal was to educate our visitors, both residents of the Virgin Islands and tourists, about the importance of mangroves to marine ecosystems. Many have been dredged because people have considered them swampy, foul smelling areas not worthy of protection. Mangroves, the backbone of the tropical ocean coastlines, are far more important to the global ocean's biosphere than previously thought.
The finger-like roots of mangrove plants protect coastal wetlands against the ocean. They protect shorelines from damaging storm and hurricane winds, waves, and floods. Mangroves also help prevent erosion by stabilizing sediments with their tangled root systems. They maintain water quality and clarity, filtering pollutants and trapping sediments originating from land. Mangroves are essential to the growth of sea grasses and are important fish habitats. They are very valuable nurseries and breeding grounds for a wide variety of fish and invertebrates.
But mangrove foliage has declined by nearly 50% over the past several decades because of increasing coastal development and damage to its habitat. In Thailand, for example, the mangroves may be entirely gone in 70 years largely due to its shrimp fishing industry and coastal development for tourism.
Researchers have learned that mangroves, which cover less than 0.1 percent of the global land surface, provide more than 10 percent of essential dissolved organic carbon that is supplied to the global ocean from land. Dissolved organic matter is an important player in the global carbon cycle that regulates atmospheric carbon dioxide and climate.
As the habitat has changed, decreasing quantities of mangrove-derived detritus are available for formation and export of dissolved organic matter to the ocean. Researchers believe rapid mangrove destruction may have serious consequences for atmospheric composition and climate.
In addition to our efforts to educate our guests about the very important role of mangroves, Coral World’s marine operations staff has participated in mangrove restoration efforts with propagules from our man-made lagoon. Mangrove seeds or propagules are unusual in that they germinate while still on the tree, sprouting seedlings that grow up to 30 cm (12 in) long. The seedlings are cigar-shaped and heavier at the root end than at the leafy end. Upon falling, they tend to plant themselves in the mud below the parent tree.
Our staff planted mangrove seedlings along a section of Coral World’s shoreline on Water Bay with limited success because of the amount of boat traffic in the bay. A more successful cooperative effort took place in quieter waters on St. John. Coral World contributed hundreds of propagules and several staff to the project. Despite the hurdles, we will continue our efforts to restore the mangroves of the Virgin Islands.