Sea Turtles in Sri Lanka and How Does Global Climate Change Impact Them?

The turtle is a long-distance traveler in the ocean. However, turtles are not limited to the sea; we can even see them on land during egg-laying and hatchling stages. Seven sea turtle species swim in the global oceans, and except for two species, all other species can be seen on the coast and sea around Sri Lanka. Additionally, they face many challenges due the climate change. We discussed this with Dudley Hemantha Perera, project coordinator of Kosgoda sea turtle conservation organization, with almost 30 years of experience in turtle conservation.  

Status of Sea Turtles in Sri Lanka and Human Impact

Sri Lanka is home to five sea turtle species, namely, Green Turtle (Chelonia mydas), Olive Ridley turtle (Lepidochelys olivacea), Hawksbill (Eretmochelys imbricata), Loggerhead (Caretta caretta) and Leatherback turtle (Dermochelys coriacea) and they nest for a long time in the coast of Sri Lanka. But, unfortunately, all sea turtle species are threatened with extinction Dadli Hemantha explained.

Sri Lanka is a very desirable place for sea turtles to lay eggs. We are not able to see these turtles all over the world. Accordingly, Sri Lanka is a critical location and a hotspot for turtles. Conservationist Dudley Hemantha explained that sea turtles come to lay eggs on the same mother beach where they were born. Many female sea turtles have used the Sri Lankan coastline to lay eggs since ancient times, which is why they are still discovered on these beaches. Human impact in the form of hunting, bycatch in fishing nets, pollution, and climate change are the main extortions to sea turtles. Let us discuss these issues scientifically based on the experiences of turtle conservationists.

Let’s start this with an event you all remember. Tons of plastic pellets from a burning containership swamped Sri Lanka’s west coast in May 2021. This caused the deaths of many female sea turtles, and the beaches that the sea turtles used so willingly were polluted. Conservationist Hemantha stated that this caused the death of many female sea turtles which never returned to Kosgoda beach. You can read more about this issue in our next article. However, the plastic pellet crisis is under control now with several drawbacks, but then again, the temperature crisis still exists.

Does Temperature Affect the Sea Turtle Life Cycle?

Despite everything, rising temperature is the main challenge to these animals. Plastic and polythene usage, fossil fuel burning, and greenhouse gas emission are the main reasons for global warming. Thus, global warming leads to more female sea turtles, which decreases population stability. Conservationist Dudley Hemantha explained that more females had been observed hatching eggs since 2010. Not only in Sri Lanka, but beaches at Playa Grande on Costa Rica’s Pacific coast are also already producing 70% to 90% female nests, depending on the year. Moreover, the northern barrier reef’s green turtle hatchlings were 99% female in the last 10 to 20 years. This is a dire situation because it is altering natural sex ratios, and it is not possible to breed the next generation by having only females.   

Typically, the eggs in the lower, cooler part of the nest will become males, while the eggs in the upper, warmer part of the nest will become females. National Geographic stated that temperature near 88˚F (31˚C) stimulates male sea turtles, and temperature near 82˚F (28˚C) stimulates female sea turtles. With increasing nest temperatures, scientists predict that more female than male hatchlings will pose a significant threat to genetic diversity.

Warmer ocean temperatures are also likely to affect food resources for sea turtles negatively. Sea turtles use coral reefs to find their primary food source. However, rising temperatures lead to coral breaching, which kills part by part of the reef, which is vital to the survival of species like the hawksbill.

Sea turtles use ocean currents to travel and find prey. Warming ocean temperatures influence migratory species by altering currents and impacting the distribution and abundance of prey species. This can result in southern species being found in the northern regions, well outside their normal range.

Turtle Deaths Reported in Kosgoda Coastal Area Last Month

Sea turtles use both marine and terrestrial habitats to complete their lifecycle. Just in the last month, two female sea turtles have been dead near the Kosgoda coast due to plastic and tangled in fishing nets, Hemantha said. One might think it is not a big problem because only two died. Nevertheless, what many people need to learn is their survival rate. Only about one in 1,000 turtles survive to adulthood. Therefore, losing the life of such female turtles is a significant loss. Adult females lay about 150 eggs at once, Hemantha added. The death of females thus dramatically affects the continued population of turtles. On the other hand, marine plastics break down into microplastics and contribute to climate change through direct GHG emissions.

Artificial Lighting, Climate Change, and Sea Turtles 

Nesting sea turtles prefer dark, quiet beaches to lay their eggs. Lights from buildings along the coast distract and confuse adult female turtles and the hatchlings. Additionally, Sri Lanka is more dependent on nonrenewable energy. As we all experience, night lights could be better managed and usefully burn fossil fuels.  Also, when the young turtles emerge from the nest at night, they are drawn toward the lights instead of the water. A single light can cause hundreds of misdirected hatchlings to be killed or dehydrated in the morning sun.  Furthermore, predators like birds, crabs, and other mammals increase their chance of being killed.

Sea Level Rise Effect on Sea Turtles 

Because sea turtles use marine and terrestrial habitats during their life cycles, the effects of climate change are likely to have a devastating impact on these endangered species. In addition, rising sea levels will influence sea turtle nesting beaches.

Sea turtles’ memory is “imprinted” with a magnetic map of the sandy beach where they hatch. This gives them the unique ability to return to that same site decades later to repeat their ancient nesting ritual. Kosgoda coast is a place that has harbored sea turtle eggs for a long period, conservationist Hemantha added.

Why are Sea Turtles important?

Coral reefs are home to Hawksbills, which eat a handful of sea sponge species. This diet allows less common types of sponges to grow, which increases the variety of life on the reef. Without Hawksbills, sponges can overgrow, causing reefs to die. Sea turtle nests on beaches contain eggshells and unhatched eggs that are left behind. This provides essential nutrients to beach grasses, which stabilize dunes and help prevent coastal erosion. Sea turtles are prey for other animals at all stages of life. Hatchlings are prey for birds, crabs, land mammals, and fish. Adult sea turtles are prey for apex predators like sharks and orcas—many sea turtle species, like jellyfish. If sea turtles vanished, jellyfish populations would explode, causing an imbalance in the marine ecosystems. Sea turtles migrate long distances; they help to transport species. They also act as an umbrella for fish that use them as shelter from predators. Sea turtles provide a diversification impact on the marine ecosystem.

In a Nutshell

Sea turtles use both marine and terrestrial environments during their life cycle. Climate change-induced temperature rise alters the natural sex ratios of sea turtles. As a result, more female sea turtles have been born in the last 10 to 20 years. Plastic menace and sea level rise are also significant threats they are facing due to climate change. Sea turtles have used Sri Lanka’s coastline since ancient times; consequently, they still come here. Finally, yet importantly, we all are responsible for saving these innocent creatures by minimizing human impacts on climate change.