There are seven different species of marine turtles. Sea turtles belong to a superfamily called Chelonioidea. The seven species of sea turtles that are left are called flatback, green, hawksbill, leatherback, loggerhead, Kemp’s ridley, and olive ridley. Sea turtles can be divided into two groups: hard-shelled and leathery-shelled. Sea turtles differ from terrestrial turtles in their body shape. Sea turtles are more spindle-shaped. This body shape helps them to swim more easily and faster because it reduces friction and drag in the water. Sea turtles range in size from 1.4 to 1.8 meters to only 60 cm, and they can weigh up to 640 kg. Sea turtles can’t pull their limbs into their shells. They have been existing on our planet for more than 100 million years. Sea turtles are found mostly in tropical and subtropical seas. They spend most of their lives at sea and come to shore only periodically to either bask or to nest.
Almost all of the species are endangered, and three of them are critically endangered. Human activity has put their survival in danger for more than 200 years. Humans have killed them for their eggs, meat, skin, and shells. They suffer from poaching and overexploitation. Turtles also suffer from habitat destruction and accidental catches because of fishing gear and pollution, especially plastic waste in oceans. Climate change has an impact on their nesting places. The rising temperature affects hatchlings sex.
Sea turtles use marine and terrestrial habitats during their life cycle, so the effects of climate change are even bigger. From the moment they hatch, the life of a sea turtle is a fight for survival. Female sea turtles lay around 1000 eggs, and only one of the hatchlings will make it to adulthood. It is because of the natural predators and also because of humans.
Sea turtles use beaches for nesting. Since climate change is melting ice and warming the oceans, it is predicted that at the end of the 21st century, the sea level will rise from 0.26 up to 0.97 meters. Already, the smallest rise has a huge impact on the beaches that are used by the turtles. Turtles memorize the beaches where they were hatched. It has been “imprinted” in their memory with a magnetic map, which means that they go back to the same beach to lay their eggs where they were once hatched. The beach habitats are also getting lost because of more severe storms. Strong winds and big waves erode the beaches, and they also flood their nests. There is, however, a possibility that as temperatures rise, the habitats of current breeding sites will become less suitable. New breeding areas that were previously unreachable, both thermally and geographically, may become available. And then yet again, scientists are saying that the sea turtles are not able to change their nesting behaviour fast enough.
Their nesting beaches are also affected by the rising temperatures. Sea turtles are reptiles, which means they rely on the outside temperatures of the sand because the eggs are incubated in the sand. The temperature is going to determine which gender the hatchlings are going to be. A higher sand temperature means that there are going to be more female turtles. So therefore, it is predicted that with increasing temperatures, there are going to be more female turtles. This will affect the genetic diversity. A study that was done with sea turtles that are found in Australia showed that 99% of the green sea turtles around Raine Island were females. Luckily, nature has its ways to solve problems. Studies that are monitoring male sea turtles in Zakynthos, Greece, have shown that males nest twice as often as females and nest with more than one female during the nesting season. Females are also able to mate with more than one male, and they are also able to store the sperm. That means that the genetic variety is a lot bigger.
Sea turtles use sea currents as highways and also to find prey. Global warming will affect migratory species by shifting the currents and affecting the spread and numbers of prey. This can lead to the southerly species being found more in the northern regions. Warm water temperatures are also having an impact on coral reefs through coral bleaching, which is crucial for the survival of species such as the hawksbill.
The oceans have absorbed about 30% of man-made carbon dioxide, resulting in ocean acidification that threatens food sources. When carbon dioxide solves in oceans, it makes a weak acid. Since more and more carbon dioxide is released into the atmosphere every day, it means that more CO2 gets dissolved in the oceans, and that makes the water even more acidic. Acidification reduces the availability of key nutrients, including nitrogen, phosphates, silica, and iron. This, in turn, reduces plankton growth. Green turtles are affected by this the most because they primarily feed on sea grasses and algae.
In conclusion, it is important to protect sea turtles because the marine ecosystem relies on them. They help to maintain the seagrass beds and coral reefs, which are useful for commercially valuable species such as shrimp, lobsters, and tunas. They also have cultural and tourism value.
Sources:
https://en.wikipedia.org/wiki/Sea_turtle
https://www.worldwildlife.org/species/sea-turtle
https://conserveturtles.org/information-sea-turtles-threats-climate-change/
https://usa.oceana.org/sea-turtles-and-climate-change/
https://climate.nasa.gov/news/2879/climate-change-puts-pressure-on-sea-turtles/
https://www.seeturtles.org/global-warming
https://medasset.org/sea-turtles/climate-change/
https://www.theguardian.com/environment/2023/feb/08/sea-turtles-under-threat-from-warming-seas-and-hotter-beaches-research-suggests
