For travelers flying or boating into the Bahamas, white sand beaches and sparking turquoise waters are the most visible signs of their arrival, but few are aware of a deep and mysterious world that lies beneath the surface of these tropical vistas. Scattered widely across the Bahamas are “blue holes”, deep water-filled holes and caves that occur both in the ocean, opening directly into a marine environment, and inland as quiet pools tucked deep in the forests with surface fresh water and deeper salt water.
Formed through millions of years of geologic events, blue holes reflect shifting climates, fluctuating sea levels, and changing plant, animal, and human communities. During the “Ice Ages” before 10,000 years ago, sea levels were more than 400 feet below todays, exposing the banks of the Bahamas as massive dry islands. Rainwater carved holes and caves in the porous limestone bedrock as it trickled deep into the earth making its way toward a lower sea level. Crystalline stalactites and stalagmites formed in the dry caves and bats and owls roosted leaving behind the skeletal remains of their kind and their prey. As the ice sheets melted by about 10,000 years ago, rising sea levels flooded the banks and filled the caves with water creating “blue holes”.
Like time capsules blue holes contain some of the most intriguing collections of natural, geologic, and human history in the West Indies. Before humans arrived in the Bahamas, animals that came to drink often fell into the holes and became trapped. Treading water, their ultimate fate was to drown and sink into dark anoxic (oxygen deprived) bottom sediments along with wind-blown leaves and vegetation that grew around the blue hole during the same time. The growing list of species includes the remains of crocodiles, the top predator of its day but now extinct in the Bahamas, large land tortoises and numerous species of birds, some that were flightless and many that are now extinct. Lucayans, the earliest humans in the Bahamas, revered blue holes and caves as spiritual portals to the world beyond life where they buried their dead. And Bahamians today are no less mystified by blue holes with legends that speak of mermaids and the Lusca, mythical sea creatures that inhabit their depths. Blue holes are now home to living species of highly specialized crustaceans and fish that inhabit the extreme environments of the flooded caves.
This is a critical time in The Bahamas as decisions about development and conservation are being made that will have long term consequences in preserving the caves and blue holes, the fresh water and marine resources, and the natural history of The Bahamas. The environment of these underground systems is extremely vulnerable to development and information from these studies is currently being used within a proposal to establish a blue holes conservation area on South Abaco as well as helping to guide the protection of blue hole and cave environments throughout the Bahamas.
For more information on efforts to protect blue holes in South Abaco, visit Friends of the Environment online at www.friendsoftheenvironment.org or email info@ friendsoftheenvrionment.com; or visit The Bahamas Caves Research Foundation at www.bahamascaves.com.