Research In Action 2022

I am not familiar with the specific beach restoration activity mentioned, but I would recommend reaching out to Florida Fish and Wildlife Commission to ask for some more information about this particular project and the efforts undertaken to minimize its impacts. There certainly can be concerns with having lights and machinery on the beach at night during nesting season.

My colleagues around the globe and I have used the hypoxic technique for egg transportation and various studies with green, olive ridley, loggerhead, flatback and leatherback turtles. Hatching success tends to decline with increasing time spent in hypoxia, with some species being capable of staying in hypoxia for longer. However, in general, for transportation purposes where eggs are maintained in hypoxia for less than 48 hours, we don't see any major declines in hatching success. Using the cooling method, there is a similar response of hatching success such that the longer eggs are kept between 4-10 degrees Celsius, the lower the success. The advantage of hypoxia is that it doesn't require ice or refrigeration. However, to my knowledge, there hasn't yet been any studies directly comparing egg chilling with using hypoxia.

It depends a lot on the local situation. For example, are there a lot of nests that are taken by human poachers each nesting season? Likewise, are the areas where turtles are nesting regularly washed over by storm surges or eroded by wave and storm activity? If so, for either of these two factors, there is a clear benefit of moving eggs to a nursery, or hatchery, because those eggs would be lost without that intervention. One con of using hatcheries is that you need the personnel available to monitor for nesting activity, relocate nests, maintain the hatchery, monitor for hatchlings, protect from poachers, and make sure subsequent hatchlings make it to the water. Another, is that the turtles spread their nests out over time and space, helping to protect them from local risks. Hatcheries put "all the eggs in one basket." Predators both on land and in the water learn where the eggs and hatchlings are. So, the risks are not eliminated.

To my knowledge, no. There are however some studies that could be relevant to this question. For example, Kemp's Ridley sea turtle eggs were translocated from Rancho Nuevo, Mexico, to Padre Island, Texas. Last century, there were thousands of eggs moved and decades later there has been an increase in mature turtles nesting at Padre Island with the goal of creating a second Kemp's Ridley nesting beach. This could be evidence that egg translocations such as this are not too disruptive to hatchling, juvenile and adult behavior, and migration. Perhaps even better evidence to support this is the case study of the Cayman Islands green turtle population. Last century, there were thousands of green turtle eggs relocated from all around the Atlantic to the Cayman Islands. Genetic studies of the adult nesting population on the beaches of the Cayman Islands have shown that turtles from these relocated eggs have now significantly contributed to the adult nesting population, with more than 95% of the population being related to the turtles from these translocated eggs.

Great question, yes, the eggs need also to be incubated at the appropriate temperature (about 25 to 34 degrees Celsius) and the appropriate moisture level. Eggs generally don't do well with flooding either, so nests ideally will have the right level of moisture without experiencing long periods of flooding.

Hypoxia (low O2) is effective to maintain embryonic arrest in every turtle species studied to date (freshwater and sea turtles). Some other reptile species may also arrest development in low oxygen as well, such as chameleons.

Increased global temperatures means that temperatures experienced by eggs incubating at nesting beaches are increasing. This has two potentially negative consequences. First, the temperature that eggs incubate at determines the sex of the resulting hatchlings, such that warm temperatures produce females and cool temperatures produce males. To make it easy to remember you can remember the phrase "hot chicks, cool dudes.” This means that turtle populations are becoming more feminized with increasing temperatures, which eventually could lead to population collapses if there are no longer enough males for the females to mate with. Secondly, eggs don't hatch if the incubation temperature gets too high. With hotter and hotter global temperatures, it is more likely that incubation temperatures during the nesting season will become too high to allow for embryonic development. Also, with hotter and drier conditions, nesting beaches can have deeper "dry fronts." Dry fronts are the top surface of the sand/beach where the sand has been significantly dehydrated and lacks moisture. Deeper dry fronts make it harder for nesting females to dig their nests as the dry sand is difficult to dig through to construct an egg chamber. This can lead to more females failing to nest and wasting energy resources on failed nesting attempts.

There are some very intelligent and talented biologists working on understanding this issue. Studies from the University of North Carolina and some performed here at FAU, have shown that turtles can sense the Earth's magnetic field and respond to different magnetic signatures by swimming in different directions. Studies have and can be performed using magnetic coils to investigate how turtles navigate under differing magnetic conditions. Experimental approaches could be used to assess when a hatchling imprints on their natal beach, the problem with these experiments is that they take decades to get definitive answers while you wait for the hatchlings to return to their natal beach and you need to do that at a large enough scale to be able to get sufficient sample size, remembering that approximately only one in a 1000 hatchlings make it to maturity. Evidence from other species (some birds) suggest that there may be several imprinting periods. Perhaps it's most important to recognize that what the turtles learn during the imprinting phase may not be very precise. After all, they hatch on beaches which are very dynamic and that are likely to change and shift before they return to the region to reproduce.

No, at least not in our experiments where we rotated eggs very early in development.

The hope for these prototype tags we have been using is to get around 90 days or three months of tracking data. We've had a lot of variation in our durations of tracks over the past two years of using them. Our current record is six months for a loggerhead sea turtle that was released from the Azores Islands in the middle of the Atlantic Ocean.

The embryonic arrest I mentioned here occurs very early in development, whilst the embryo is still what's called a "gastrula." The embryo is about 100 cells or so at this point. The sex of a sea turtle is determined by the temperature the embryo experiences during the middle third of development, so much later in development. So, there is no direct link between embryonic arrest and sex ratios of the hatchlings.

As these tags were only deployed a few months ago, we are still working on analyzing these tracks. However, it was impressive to see, at a macro level, that these turtles dispersed in a wide range of directions from the Cayman Islands even though there are strong current systems within the Caribbean. This suggests that these turtles are capable of actively dispersing in directions that are not necessarily in the same direction as prevailing currents. This provides further evidence that sea turtles are not merely 'passively drifting' with currents during their lost years.

Funding is critical, but the technological advancements are the main requirement for smaller satellite tags. Engineers need to be able to design smaller tags, but this is dependent on microchip, battery and circuitry technology become more miniaturized.

Yes. In leatherbacks we see a lot of early-stage embryonic death and late-stage embryonic death. In the other species we see less embryonic death in general.

Tracking technology may eventually advance to this stage. However, there are techniques available already which can help researchers understand turtle migration across their entire life. For example, genetic techniques can be used. Genetic fingerprinting is a technique where researchers take a small genetic sample from hatchling turtles and then can monitor foraging grounds or nesting beaches and take further genetic samples from juvenile or adult turtles in these areas and look for matches in the 'genetic fingerprint' from hatchling turtles that hatched in previous years. This is already being conducted by Kelly Stewart and collaborators in St. Croix with the leatherback turtle nesting population there.