New Key Helps Identify Why Some Sea Turtle Eggs Fail to Hatch

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The development of a sea turtle embryo is a relative mystery to researchers. However, a recent study in Chelonian Conservation and Biology explores a new staging key that may help scientists learn more about this topic and the related factors that affect sea turtle development.

Chelonian Conservation and Biology, Volume 16 Issue 2 cover

Chelonian Conservation and Biology, Volume 16 Issue 2

The use of a staging key allows researchers to quickly estimate when during incubation an embryo died.

Chelonian Conservation and Biology – Despite a long history of studying sea turtles, researchers know little about how a turtle develops while within its egg in the nesting beach. This creates a puzzling mystery for researchers when turtles don’t emerge from their eggs. A new staging key could help researchers learn why some turtle eggs fail to hatch and whether this failure signals bigger problems for the incubating beaches and their sea turtle populations.

An article published by an international team of researchers in the current issue of Chelonian Conservation and Biology presents a field key that shows and describes the developmental stages of sea turtles before they hatch. The key could help researchers identify the cause of death for specific clutches of unhatched turtles. It may also allow various turtle researchers involved in a range of projects to standardize and compare their data and potentially spot wider trends in sea turtle deaths.

Sea turtle research projects typically count hatchlings or study vacated nests to learn about nesting females and their offspring. Sometimes, however, few of the eggs in a turtle nest hatch, making that site unavailable to hatchling count and empty nest studies. Because of this, researchers need a quick, straightforward way to estimate when the unhatched turtles likely died. Changes in temperature and other beach conditions are potential factors when turtle eggs fail to hatch, and aligning estimated time of death with recorded weather conditions can help field researchers determine the potential cause of death. Timing and cause predictions can reveal information about the health of the beach incubating the turtle nest and whether it protected and supported the development of the eggs.

The field key presented in this article tracks when visible, outward features, like eye bulges and flipper scales, appear as a sea turtle develops. Researchers can use it to place a turtle’s developmental stage within a window between when the eggs were laid and when the hatchling was expected to leave the egg. When they compare it with data about weather and ocean events, they can begin to identify factors that may have caused a turtle to die before it hatched.

“The use of a staging key allows researchers to quickly estimate when during incubation an embryo died,” said Jeff Miller, an author of the article. “Although not perfect, such a correlation (between external events and developmental stages) can help identify factors that may be causing the reduction in hatching success and guide more focused research.”

The authors predict that their staging key will help field researchers estimate when unborn turtles died. By reviewing data related to the nest, its beach, and the weather, researchers can then speculate about the likely causes of death. Such predictions could be used to improve future field experiments related to the developmental stages of marine turtles.

Full text of the article “A Field Key to the Developmental Stages of Marine Turtles (Cheloniidae) with Notes on the Development of Dermochelys,” Chelonian Conservation and Biology, Vol. 16, No. 2, 2017, is now available at http://www.chelonianjournals.org/doi/full/10.2744/CCB-1261.1.

About Chelonian Conservation and Biology
Chelonian Conservation and Biology is an international scientific journal of turtle and tortoise research. Its objective is to share any aspects of research on turtles and tortoises. Of special interest are articles dealing with conservation biology, systematic relationships, chelonian diversity, geographic distribution, natural history, ecology, reproduction, morphology and natural variation, population status, husbandry, community conservation initiatives, and human exploitation or conservation management issues. For more information, please visit http://www.chelonian.org/ccb/.

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Caitlyn Ziegler
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