By Mary Pringle for The Island Eye News
Photos by Barb Bergwerf
We may not realize it but the presence of sea turtles in our world is important to our marine ecosystem in many ways. They have played an important role for over 100 million years in maintaining the health of the ocean and even benefit animal and plant life on our beaches. As the ocean has become less healthy due to pollution from plastics and other debris, our turtles are still helping to maintain the very important ecosystems that are so vitally linked together.
For example, green sea turtles who are vegetarians as adults graze on seagrass beds on the ocean floor which would become overgrown without this regular harvesting. Currents would be obstructed and slime mold, algae and fungi would take over.
This would bring about harmful impacts on reef fish that people eat and other plant species.
Another species of Atlantic sea turtle, the hawksbill, specializes in eating sponges found in coral reefs. We never have hawksbill turtles in South Carolina because they are found farther south in the Caribbean Sea. They are adapted with beaklike mouths to get into crevices to reach these sponges which compete with the corals growing there and give the corals a healthier space to colonize and grow. This makes for a healthier and more diverse reef.
Leatherback sea turtles pass by our coast early in the season on their northward migration after nesting. These are the huge black turtles that often get hit by ship propellers offshore. In April of this year we reported five of them on our two islands. Four of these died as victims of propellers and one was entangled in a crab trap rope behind Sullivan’s Island and freed by the Fire & Rescue Squad. They feed on jellyfish and can consume as much as 440 lbs. (the weight of an African lion) in jellyfish in one day. This is another example of the balance of nature. Without these turtles populations of jellyfish would spiral out of control.
Our beloved loggerhead turtles who nest here are called “loggerheads” because their heads are the largest in proportion to their bodies.
These strong jaws supported by large muscles are able to crush the heavy shells of blue crabs, whelks, lobsters and other crustaceans. These turtles move along the ocean floor creating paths which benefit other species by aeration, compaction, and feeding opportunities that are beneficial. Our loggerheads also feast on jellyfish.
Even though we hate to think of it, turtle eggs laid on our beaches help other animals to survive when they are eaten. Think of the 266,293 plus loggerhead eggs that have been laid in South Carolina this season. Most of these will not produce adult turtles, but they will enable other species on land to eat and survive. Leatherbacks feed on jellyfish near the Arctic Circle but then lay eggs in the Caribbean nourishing other creatures there.
When we conduct nest inventories, we always deposit the unhatched eggs and eggshells back into the sand on the dunes on the Isle of Palms.
This is very beneficial to the sea oats and other dune vegetation in sandy soil that has very few other nutrients. Unfortunately on Sullivan’s Island we must follow the instructions of the SC Department of Natural resources and take the leftover contents of the nests off the beach in order to keep coyotes from digging them up. Coyotes are new here and we do not want to teach them the rewards of following the scent of sea turtles and digging up nests – even nests where the hatchlings have already hatched and gone into the water. Sometimes in a very dry summer, the roots of dune plants will invade the egg chamber and penetrate the eggs in search of moisture. Fortunately this summer has brought plenty of rain and this doesn’t seem to be happening right now.
So these benefits that the ocean and the beach receive from sea turtles are important in keeping the natural balance in the ocean and on the beach.
These ideas were inspired by an article published by Oceana, a worldwide nonprofit organization founded in 2001 which works to protect the world’s oceans.