Hotter oceans are bad news for sea turtles, and humans

As climate change alters temperatures and habitat conditions all around the world, species are struggling to adapt. With rising sea temperatures, many marine organisms face the threat of extinction. These temperature increases have potential to harm already endangered sea turtle populations.

According to the International Union for Conservation of Nature, six sea turtle species are labelled endangered or critically endangered. Sea turtles are endangered for many reasons, including loss of nesting habitats, human and predator disturbance of nests, and predation. Rising sea and sand temperatures, however, add to the burden that sea turtles are already facing.

In sea turtles, whether an individual becomes a male or female is determined by the temperature in which the eggs are incubated. Higher incubation temperatures (above 29 C), produce more female turtles, and cooler incubation temperatures (below 29 C), produce more male turtles. Fluctuating warm and cool incubation temperatures result in a nearly even mix of male and female offspring. Climate change is causing an increase in sea and sand temperatures, making sea turtle nests hotter. This means more female turtles are being born than males. Fewer than 0.1 per cent of sea turtles survive to adulthood, and if most of these are females, there may not be enough males to mate with females. Rising sea and sand temperatures also cause more eggs to die before hatching, further threatening these endangered species.

But why is the decline of sea turtle populations something we should care about? Sea turtles play an important role in maintaining balance in the marine ecosystems they live in.

For example, loggerhead turtles in Mexico play a key role in nutrient cycling. Loggerheads remove nutrients from the water as they eat, and deposit their nutrient-rich eggs on sandy beaches. This moves energy from the nutrient-rich sea water to the nutrient-poor beaches, fuelling the growth of vegetation that stabilizes shorelines. This helps prevent erosion, and simultaneously keeps the nutrient levels in the sea water at healthy levels. This protects our water bodies from eutrophication, which happens when nutrient concentrations increase too much, leading to harmful algal blooms. These algal blooms use up the oxygen in the water and block sunlight from penetrating the water column, killing wildlife and making the water even more toxic — a vicious cycle. Since so few turtle hatchlings return to the sea after hatching, much of the nutrients deposited remain in the sand, protecting the water from the effects of excess nutrients. This is just one example of how crucial sea turtles are to ecosystem health and balance.

Sea turtle conservation efforts have been underway for many years. These efforts include designating protected areas for sea turtle nesting, protecting new hatchlings as they make their way to the sea for the first time, and raising clutches in artificial nests to control incubation temperatures and balance the sexes.

Although these efforts have been successful in slowing the extinction of some sea turtle species, they can be expensive, time consuming, and labourintensive. Anthropogenic climate change continues to worsen, posing a significant threat to our planet’s species at risk — including many species that are already at risk of extinction — like sea turtles. As climate change worsens, more viable solutions are needed for long-term management of species at risk. The actions we take to protect sea turtles will also ensure a healthier future for ourselves as they play an essential role in keeping our planet healthy and balanced.