A recent experiment documented profound impacts of increased nesting temperatures on the hatchlings of Loggerhead Sea Turtles. The study was led by researchers at Florida Atlantic University. It shows that increased warmth in the nest leads to a quicker incubation time with less hatching success, a slower growth after hatch, and an increase of physical defects of hatchlings. According to the recent research, these results are alarming for the future of Loggerhead Sea Turtles as global temperatures continue to rise.
The research focused on Loggerhead Sea Turtle hatchlings incubated at two different temperatures: 88 degrees Fahrenheit and 91 degrees Fahrenheit. The study primarily focused on how these fluctuating temperatures affected the physical and cognitive development of the hatchlings. Eggs are collected from local nesting beaches during the summer months of 2019 and 2020. These regions have already seen sand temperatures surpass 93 degrees, approaching 96 degrees Fahrenheit.
Impact of Higher Temperatures on Incubation and Hatching Success
Loggerhead Sea Turtle hatchlings that developed in nests incubated at 91 °F exhibited concerning trends. These disturbing trends give cause for much alarm as it pertains to their existence and growth. Importantly, these hatchlings had an incubation period that was several days shorter than those hatched at 88°F. This apparently beneficial characteristic was eclipsed by a sharp drop in hatching success. The hatchlings from the hotter nests were less likely to survive across the board. This begs the question of whether they can continue to succeed in growing climates that are getting hotter.
Additionally, hatchlings from the warmer treatment had reduced post-hatch growth. Even a small growth rate decrease can be enough to doom them in the long run.
Survival
Larger and healthier hatchlings have a greater likelihood of escaping predation as well as successfully competing for resources once returned to their natural environment. In the process, they noticed a troubling increase in scute abnormalities in hatchlings from those hotter nests. These flaws erode the symmetry of the scales that cover the turtles’ shells. We noticed that these ranched anomalies were exclusively on the vertebral scutes. These scutes serve an important role in protecting adult turtles.
Assessing Cognitive Abilities Under Heat Stress
The research adopted a pioneering scope by assessing the cognitive skills of Loggerhead Sea Turtle hatchlings. It specifically considered how different temperatures influenced their development. Using a Y-maze to test spatial learning and a visual discrimination task to measure cue-learning, researchers wanted to quantify how sharp these hatchlings were. In these experiments, hatchlings were conditioned to learn a unique monochromatic pattern as associated with a food reward.
The results revealed promising insights. Loggerhead Sea Turtle Hatchlings performed well on both acquisition and reversal tasks in the study. Those in the hotter temperature group saw their performance drastically increase throughout the reversal phase of training during 2020. They memorized information at a much quicker pace than they did during their original training exercises. This surprising finding demonstrates that increased nesting temperatures have sublethal, cascade effects, further compromising the physical development of hatchlings. These hatchlings do have something of a superpower when it comes to learning.
Implications for Future Conservation Efforts
This study is more than mere academic interest. With climate change severely affecting coastal ecosystems, the report emphasizes the immediate need for targeted conservation strategies. Elevated sand temperatures reduce hatching success and negatively impact hatchling performance in Loggerhead Sea Turtles. With nesting beaches in South Florida already experiencing sand temperatures above critical thresholds, conservationists are compelled to consider how these environmental changes will impact future generations of sea turtles.
Sarah L. Milton, Ph.D., chair of the FAU Department of Biological Sciences, is senior author. She’s passionate about ensuring that this research gets done. Most importantly, she says, figuring out how temperature relates to developmental outcomes is crucial for determining the most effective conservation strategies. Climate Change Climate scientists have been raising the alarm over increasing global temperatures for years. It’s more important than ever to conserve nesting habitats and combat climate change impacts on imperiled species such as the Loggerhead Sea Turtle.