Uncertain future for global sea turtle populations in the face of sea level rise

Environment | Oceans

By Rebecca Hurford, Freelance writer

Published October 24th, 2023

Sea levels rising due to the Arctic ice melting is having a considerable impact on marine species. New research suggests that ‘by 2050 it is predicted that at some sea turtle nesting habitats 100% will be flooded and under an extreme scenario many sea turtle rookeries could vanish.’

Sea level rise has been a consistent issue in the last couple of decades, and with the early onset of Antarctic ice sheet instability, it is predicted that the global sea level rise‘will reach 82 centimetres and—in extreme scenarios—could exceed two metres’.

Turtle nesting beaches with low slopes may be at risk in the expected increase in sea level rise. | Joe Cook / Unsplash

The rise of sea levels is threatening many oceanic species. Sea turtles are a reptile species that have been around for nearly 110 million years and are now in severe danger, with three out of seven sea turtle species being critically endangered.

There are seven identified species of sea turtles; the Green Head, LoggerHead, Hawksbill, Leatherback, Kemp’s Ridley, Olive Ridley and Flatback sea turtles. The most vulnerable habitats to sea level rise are those off of small tropical islands, which are the habitats that the majority of sea turtles live in. Many of the species are facing nesting complications due to increasing sea levels.

‘Three out of seven sea turtle species being critically endangered.’

A 2023 study has investigated the effect of sea level rise on five nesting sea turtle species, all classed as vulnerable or critically endangered. The study used modelling to assess how the future of the species would be impacted.

Modelling results predict that in an occasional flooding scenario (or moderate scenario), there would be a massive impact on sea turtle nesting habitats on land and that ‘on average, 50% leatherback, 18.2% hawksbill and 13.1% of green turtle nest locations would be flooded by 2050’..

Overall, leatherbacks were identified as the sea turtle species at higher risk from flooding compared to other species studied, due to their tendency to nest in open areas near high tide. Moreover, the model’s ability to predict these areas as potential nesting sites was 79.4% accurate.

Leatherback turtles are at high risk of losing nesting beaches according to a recent study. | Cataloging Nature / Flickr

These figures are concerning, especially considering stabilising global greenhouse emissions to counteract rising sea levels is a challenging prospect that entails significant global cooperation. Researchers also emphasised the importance of monitoring these habitats to understand the projection of the rookeries and how we can help sea turtles nest safely.

The countries surveyed were Costa Rica, Cuba, the United States- specifically Florida, Ecuador and Australia. However, the research stated that the nesting habitats of sea turtles are usually in poorer countries that cannot afford the technology to monitor the state of the terrestrial land.

‘On average, 50% leatherback, 18.2% hawksbill and 13.1% of green turtle nest locations would be flooded by 2050’

Another recent study showed the effect of climate change on Mediterranean marine life and looked closely at threatened species including sea turtles.

The study aims to elucidate how these species will adapt to, or be impacted by, the changing climate. Results suggest that the flooding of sea turtle nesting beaches will likely cause this species to struggle to reproduce. Looking to the future, there may be fewer sea turtle rookeries and there could be a 100% loss of nesting beaches in places such as Australia and Florida.

The nesting process of sea turtles goes back millions of years, unfortunately, this process is being threatened by anthropogenic climate change having a serious effect on sea turtle reproduction.

During the reproduction process, sea turtles will return to land to find a suitable nesting location for their young. Each time a female sea turtle nests she tends to go back to a nesting location she has previously used or is at least familiar with. When nesting, the female will create a ‘body pit’, with her flippers in the sand, this will create a perfect arrangement for her to nest.

Green sea turtle laying eggs. | Francesco Veronesi / Flickr

Monitoring the situation and the beaches where the sea turtles nest is a successful way that we can help identify nesting locations for female sea turtles. For example, a recent study trialled researchers using drones to take images to photograph structures of different sea turtles nesting on beaches in north Cyprus.

Researchers from the Centre for Ecology and Conservation at the University of Exeter, UK, describe 'automated drone surveillance which can record sequences of photos on the surface below, then merged to construct three-dimensional models of the survey area in a process called photogrammetry.'

Therefore, these drones can quickly help to identify which beaches need to be prioritised for local conservation. Charities such as the World Wide Fund for Nature (WWF) are working with local communities in Indonesia, Ecuador and Fiji to prevent the beaches from completely flooding.

‘Results suggest sea turtle nesting beaches flooding will likely cause this species to struggle to reproduce.’

Although local communities can try their best to conserve the beaches, it is also important that global greenhouse emissions are decreased to mitigate global sea level rise. This is essential for sea turtles to be able to successfully nest and for other marine life to survive in their natural habitats.

Featured Image: Jessica Wong | Unsplash

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