Loggerhead and Green Sea Turtle Night Research: 20K Nests and FAU/LMC Collaborative Research Update

As the loggerheads start saying ‘goodbye’ to the 2019 nesting season, greens continue to come ashore to nest! We officially broke 20,000 recorded nests this past week and currently have 20,109 total nests. Loggerheads still lead the way by a large margin (13,243) followed by greens (6,679) and leatherbacks (187).

Trina, one of the final loggerheads we sampled this season. (Photo: Derek Aoki)

The LMC night crew only has a few more surveys left in this season, as our quota for greens and loggerheads has almost been reached. However, we are still out for a few more turtles to take blood, tag, and measure. The greens have been tricky to sample of late and we have not encountered many loggerheads. Hopefully our luck will turn around!

Director of Research Justin Perrault carefully takes a blood sample from a nesting green turtle. (Photo: Derek Aoki)

This week we will cover another master’s research project that is underway on our Juno and Jupiter beaches. FAU student and LMC Morning Technician Heather Seaman is working long mornings and often longer nights as she examines how sand characteristics influence sea turtle development in their nests. Her results could reveal which sand properties are influencing the conditions inside a nest and how they are impacting the performance and survival of the baby turtles!!

She is particularly interested in temperature and oxygen levels in nests. Heather is looking to see their impact on hatchling and emergence success as well as hatchling performance. She is also correlating temperature and oxygen with the presence of heat shock proteins and correlating these proteins with hatchling performance. Finally, she wants to see if sand grain size and color impact temperature and oxygen levels in a nest.

An example of one of Heather’s nests, consisting of a perimeter, a data logger inside the clutch, and an oxygen tube. (Photo: Derek Aoki)

Temperature plays a huge role in a nest’s development as well as determining the sex of the hatchling! But due to factors like climate change, nests can experience extreme temperatures. This can aid in hatchling mortality, but the baby turtles can also developed physiological responses to combat extreme heat. One such indicator is heat shock proteins. As turtles are exposed to extreme temperatures, they exhibit an increased expression in these proteins. This could actually allow them to tolerate higher temperatures, thus increasing their survival and fitness chances! To test this, Heather has placed data loggers in various nests that will monitor the temperature in the clutch. She also takes a blood sample from hatchlings to look for any expression of heat shock proteins.

Data loggers like this will help Heather analyze the temperature of nests to see what impact it plays on a nest’s success and hatchling performance. (Photo: Derek Aoki)

Gas exchange, particularly oxygen, is another factor that plays a big part in the growth of a sea turtle embryo. Various sand characteristics such as grain size and water potential can effect the amount of oxygen a nest receives. If oxygen levels become too low, for example as a result of an increase in sand temperature, hatchling success and fitness could be negatively affected. To examine this, she has placed oxygen tubes in her nests and records the oxygen and carbon dioxide levels to see how they change over the course of the nest’s development.

FAU master student Heather Seaman takes an oxygen and carbon dioxide reading from a nests. The cage is to trap any hatchlings that may emerge so she can perform her performance trials. But not to worry, the cages are only closed when she is monitoring the beach at night and are open during the day! (Photo: Derek Aoki)

Once a nest hatches, she collects a certain number of hatchlings and conducts fitness trials. These consist of a flip test (to see how long takes a hatchling to flip over from its back) and a crawl test (to see how long it takes them to crawl a set distance). This is also when she takes the blood sample from the baby turtle. Then three days after the hatchout, she returns to the nest and performs an excavation. Here, she determines the emergence and hatchling success rate and collects her sand samples.

Heather performing a nest excavation on a leatherback nest. She will calculate the hatchling and emergence success, then link it with the nest’s temperature and oxygen levels. (Photo: Derek Aoki)

As we close this blog post, all of us in the Research Department wish Heather the best of luck with her project!! Thanks for reading and come back next week as we start to close out our 2019 night surveys!

Disclaimer: All marine turtle images taken in Florida were obtained with the approval of the U.S. Fish & Wildlife Service (USFWS) and the Florida Fish & Wildlife Conservation Commission (FWC) under conditions not harmful to this or other turtles. Images were acquired while conducting authorized research activities pursuant to FWC MTP-19-205.