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Are Rising Ocean Temperatures Causing More Sea Turtles To Be Born Female?


Here at Wildlife Conservation Association (WCA) there is a heavy focus on sea turtle conservation through community action, education, and ecotourism. The Olive Ridley turtles come to shore in droves during a mass-nesting event called an arribada. The National Oceanic and Atmospheric Administration (NOAA) estimates that 600,000 nesting olive ridleys come to shore between the two major arribada beaches - Nancite and Ostional (where WCA is located). As global climate changes occur, the impacts are felt around the world and by many species, including sea turtles.


Scientists are now researching how warming temperatures are affecting turtle populations in ways that were previously unfounded. Temperature Dependent Sex Determination (TSD) means that gender in sea turtles, similar to alligators and crocodiles, is not determined by fertilization but rather by sand and nest temperatures. When the pivotal threshold is reached, which is set at 29 degrees Centigrade, otherwise known as the threshold temperature, a hatch of 100 babies would yield a perfect ratio of 50 males 50 females.


Effects of climate change reverberate around the world, impacting many different species and ecosystems. As sea levels rise, beaches get physically smaller, leaving less space for nesting sea turtles. The impacts of warming sands on gender ratios of sea turtle populations are noted in Florida and Australia. According to a recent study on sea turtles that nest on the Pacific Coast in Costa Rica average incubation temperatures fall around 32.3 degrees Centigrade. As sand and nest temperatures climb globally, researchers are finding that more females are being born in males. There are many scientific communities worried about populations of turtles being completely feminized, which then could ultimately die out due to lack of male turtles. Scientists estimate that up to 93% of green turtle hatchlings could be female by 2100, as climate change causes ‘feminization’ of species. This warming of temperatures and shift towards feminization also creates a threat to genetic diversity of different populations of the species.


In the sea turtle world, there’s an easy way to remember how temperature impacts gender: “Cool Dudes. Hot Chicks”


Researchers at the Florida Atlantic University have found that temperatures below 27 degrees Centigrade produce all-male hatchlings, while temperatures above 31 degrees Centigrade produce all female hatchlings.

What Can You Do To Help?

As the name implies, global climate change is a global problem. To mitigate the effect of climate change, there needs to be a global collective effort to reduce our waste - if we all contribute to the solution, there is a greater chance for effective change. If everyone takes small steps in their daily lives, the impact can be great. Several potential changes we can make include:


  • Purchase Energy-Star qualified appliances

  • Replace incandescent light bulbs with energy-efficient fluorescents

  • Reduce, reuse, and recycle all plastic, glass and paper waste

  • Use energy-saving methods of transportation

  • Tell a friend about the problems the sea turtles and Earth are facing; knowledge is power and collective influence can force change

  • Plant vegetation along beaches to provide better nesting habitat

  • Look for alternative sources of energy, like solar or wind

  • Write to law makers to encourage more efficient use of energy

Conclusion

Global climate change is the result of human-activities that have been detrimental across the world and impacted many ecosystems. One major ecosystem that many species use would be beaches, humans use it for recreation, other species use it for different parts of their life cycle. The species WCA is focused on are sea turtles who use the beaches for nesting, which are being impacted by sea level rise and warming temperatures. There are steps we can take, because a problem caused on a global scale must be solved on a global scale; climate change has been affected by individual activity and larger scale activity, which is how it will be solved, too.

The WCA in action

We're thrilled to announce the reinstallation of the WCA's marine buoy this month, sponsored by Sofar Ocean!

WCA works towards conservation of many species, especially those found in Ostional and nearby beaches. The marine buoy plays a crucial role in collecting first-of-its-kind data for our coastal waters. It enables us to measure sea surface and temperature at depth, as well as various wave parameters such as swell height, period, and direction.


Currently, all existing data is derived from models, lacking real local data. That's why this initiative is so important. Measuring temperature at depth is particularly significant for understanding coral health and the impacts of climate change. By having accurate and locally sourced data, we can gain valuable insights into preserving our marine ecosystems.


The marine buoy was initially deployed in January 2022 in the waters off the coast of Ostional. However, we faced a setback when the buoy was unfortunately vandalized shortly after its launch.


But, this experience taught us a valuable lesson: lasting change requires the collective efforts of our entire community! From the project's inception to completion, we actively involve fishermen, guides, and locals, ensuring that all voices are heard and respected.


The data is live and available for our whole community to view here.

 

References


  1. NOAA. Olive Ridley Turtle. NOAA Species Directory. https://www.fisheries.noaa.gov/species/olive-ridley-turtle

  2. University of Exeter. "Warming warning over turtle feminization." ScienceDaily. ScienceDaily, 19 December 2018. <www.sciencedaily.com/releases/2018/12/181219191044.htm>

  3. Tezak, B. A New Approach to Identifying Sex in Hatchling Turtles, and a Potential Game-Changer for Assessing Marine Turtle Hatchling Sex Ratios. Charles E. Schmidt College of Science – Florida Atlantic University. http://savetheseaturtle.org/A-New-Approach-to-Identifying-Sex-in-Hatchling-Turtles.html

  4. Sea Turtle Conservancy. Information About Sea Turtles: Threats from Climate Change. https://conserveturtles.org/information-sea-turtles-threats-climate-change/#:~:text=With%20increasing%20nest%20temperatures%2C%20scientists,and%20virtually%20all%20marine%20species.


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ENVIRONMENT • SUSTAINABILITY • EDUCATION

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