Turtles in Southern African Waters

Turtles

 

Turtles in Southern African Waters


As the harsh African sun slips beneath the western horizon and the color begins to fade from the sky, darkness descends upon the beach. The ghost crabs prehistoric bodies are illuminated by the silvery glint of the moon as they scurry back and forth mimicking the ebb and flow of the waves. As mile after mile fades behind us our headlights failing to penetrate the misty moisture laden sea air, we advance in perpetual gloom. The animals we have come to seek have come to the end of a very climatic journey on this remote and lonely beach, where they have come to deliver their packages of life, their future, their eggs.

Only two species of turtle nest on the beaches of Southern Africa, the Loggerhead, who weighs approximately 110 kg and the much larger Leatherback which averages in the region of 400 kg’s. The pelagic Leatherbacks have been roaming the deep ocean where they spend their days feeding on the huge blimp like jellyfish.  The smaller Loggerhead’s spend there time closer to the shore where they live on a shellfish diet.

Both these species mate offshore and when the fertilized eggs inside the female are fully developed and ready to be laid she will head for the beach, the same beach where she hatched from her shell more than twenty years previously. As nobody yet really understands this phenomenon, scientists believe, that during the short time spent on the beach, the tiny hatchlings instinctively acquire the smell, which permeates from the sand.  This natural homing device enables the sexually mature female, her body laden with eggs, to navigate her way back to her birthplace and repeat the cycle of life.

When the time comes to lay her precious cargo, the mature female turtle will linger offshore until nightfall, waiting for the right opportunity to embark on the final leg of her journey.   She will enter the wash zone between the breakers and scouts out if the coast is clear. The slightest disturbance at this stage will cause her to immediately turn her bulky body around and return to the safety of the sea. Sensing no imminent threats, she slowly and purposefully drags herself up the beach on flippers that were designed for a totally different purpose.  The effort of dragging her huge bulky body through the high tide mark and into the dune vegetation consumes an enormous amount of energy.  The final leg of her journey is the most difficult.  She takes several cumbersome drags and then pauses for a short rest, repeating this sequence until she reaches a suitable nesting site.  It is not uncommon for female turtles to travel onto the beach, not find the ideal nesting spot, and return to the sea, without having laid a single egg.  Should this be the case, the female in all likelihood will return the following evening and attempt to find a better location where she can lay her eggs.

Once her nursery has been chosen she will commence digging. Using her front flippers she will clear an area big enough for her body and about 30 cm deep, in which she will settle. Using her deft hind flippers she excavates a chamber into which she deposits her precious cargo. The eggs are soft and leathery, so the short drop into the hole poses no danger of breakages. Loggerheads lay about a hundred eggs at a time and the Leatherbacks lay close to 120 eggs per nesting. In a season the Loggerheads can lay a total of five hundred eggs, whereas the Leatherbacks deposit almost a thousand. Once she has discharged all her eggs, the female covers the nest with beach sand and then painstakingly flings sand over a huge area around the site in order to disguise her cache. After two hours on land, she laboriously makes her way back to the sea.

For 55 to 65 days the warm African sun incubates the eggs. Once the hatchlings reach maturity, they will use an egg tooth to assist them in breaking free from the confines of their leathery shell. The entire nest can take up to two days to hatch out completely and when all the hatchlings are freed from their natal homes they begin to work through the beach sand, which has acted as a temperature regulator and a protector from potential nest robbers.  The hatchlings will rest just below the surface of the sand and wait until the cooling temperatures announce the onset of nightfall.  The dark cloak of night envelopes the beach and the hatchlings scramble through the last bit of sand and emerge on the surface.  

They are about to set out on the most arduous leg of their journey, a deadly dash down the beach towards the seemingly benign sea.   It is now during this short run that land based predators become a formidable barrier. The ghost crabs that scuttle around in the wake of the waves will form part of the gauntlet that the vulnerable hatchlings will have to break through in order to reach the so-called safety of the sea. In this short journey up to 12% of the nest can fall victim to the crabs.  Jackals, genets or monitor lizards, who happen to be in the right place at the right time, find themselves in the midst of a veritable feast, and eagerly devour the tiny turtles. Even a marauding party of ants is enough to succumb a hatchling. These natural obstacles are not the only barriers to the hatchlings survival.  Tire tracks left behind by ignorant humans are like mountains to the tired hatchlings and often become an insurmountable wall that bar the young turtles from embarking on their life’s journey, which only begins once they reach the sea.  However, the ocean has an even greater abundance of predators to thwart the hatchlings, and many fall prey to predatory fish such as barracuda, kingfish and sharks, not too mention the predatory birds that fly overhead such as gannets, gulls and frigates.

In a couple of decades, only one or two resilient young turtles, out of a thousand, will mature and commence the same journey as their mother, aided by nature’s instinctive tracking system, they will travel the oceans and find their way home to their birth place and resume the cycle of life.

Similar to so many species around the world, the biggest threat to the Loggerhead and Leatherback turtles is man.  Poaching of eggs and consumption of turtle meat has been a growing concern facing the turtles.  Even though man has been exploiting this natural resource for many years, it is the culmination of a number of issues in addition to the poaching, which is causing a major decline in population numbers. Habitat loss is occurring due to the construction of beach resorts.  Once pristine beaches have been transformed into playgrounds and retreats for holiday seeking people.  Turtles are photo tactic, light sensitive, and the bright lights from these new developments, disorientates the turtles, keeping them away from their natural nesting grounds. Another concern facing turtles is long line fishing for tuna, which in South America alone accounts for about 2000 deaths annually. The latest and most insidious problem the turtles have to face is AIDS.  The disease itself does not affect the turtles, but to many local people afflicted with the autoimmune disease, turtle eggs are falsely believed to be a cure and hence a new demand for the eggs has been established.

Numerous efforts around the world are being made to help protect sea turtles and their habitats.  The turtle-monitoring project on the South Eastern coast of Southern Africa was started thirty-six years ago and it continues today under the watchful eye of the KwaZulu Natal Nature Conservation Services. The KZN NCS has teamed up with conservation groups, tourism and local communities to ensure the future survival of these creatures that have been around for more than 150 million years. Local communities help with the data and hatchling collection, while conservation and tourism bodies use their expertise in fund raising. Only through education and dissemination of accurate information can we possibly hope to save these ancient creatures.  


  

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