BEACH NOURISHMENT AND ITS EFFECT ON SEX DETERMINATION OF LOGGERHEAD HATCHLINGS

Heather Hoffmann

Sea Turtle Intern at Bald Head Island Conservancy

BACKGROUND

¢ Temperature dependent sex determination ¢ Thermosensitive period

�  7-15 days in middle third of incubation

¢ Hormones in TSD systems �  Aromatase enzyme affected by temperature

BACKGROUND

¢ Bald Head Island �  Northern nesting point

¢ Beach nourishment becoming a problem �  Effect on male to female ratio?

¢ Human impact on endangered species

INTRODUCTION ¢ Summer research project with BHIC ¢ Understand effects of beach nourishment on nest

temperature ¢ Temperature sensors in nests ¢ Nourished and non-nourished beaches ¢ Beach nourishment and its affect on temperature

dependent sex determination of Loggerhead sea turtle (Caretta caretta) hatchlings on Bald Head Island.

POTENTIAL QUESTIONS

1.  Does beach nourishment affect sea turtle hatchlings?

2.  What is the average temperature profile in nests over the entire incubation period?

3.  How does metabolic heating affect temperature within the nest?

4.  Is there a correlation between average nest temperature and incubation time?

5.  How does average nest temperature affect survival rates of the nest?

6.  Is beach nourishment affecting male to female ratios of hatchlings?

GENERAL HYPOTHESIS

¢ Based on preliminary background research I predict that nourished beaches will generally have higher average nest temperatures resulting in more female hatchlings

MATERIALS AND METHODS

¢  20 temperature sensors �  Middle of nest while laying �  Removed during excavations

¢ Nourished and non-nourished beaches

¢ Control logger 1 meter to the left

¢ Sensors record average temp for 50-70 days

CONCLUSION

¢ Waiting to collect loggers ¢ Analyze data and determine if correlations exist ¢ Using data for honors thesis at OSU

WORKS CITED

DeGregorio, B.A. and A.S. Williard. 2011. Incubation temperatures and metabolic heating of relocated and in situ loggerhead sea turtle (Caretta caretta) nests at a northern Rookery. Chelonian Conservation and Biology 10(1): 54-61

Hawkes, L.A., A.C. Broderick, M.H. Godfrey and B.J. Godley. 2005. Status of

nesting loggerhead turtles Caretta caretta at Bald Head Island (North Carolina, USA) after 24 years of intensive monitoring conservation. ORYX 39 (1): 65-72.

Hawkes, L.A., A.C. Broderick, M.H. Godfrey and B.J. Godley. 2007. Investigating

the potential impacts of climate change on a marine turtle population. Global Change Biology 13: 1-10.

Rumbold, D.G, P.W. Davis and C. Perretta. 2001. Estimating the effect of beach

nourishment on Caretta caretta (Loggerhead Sea Turtle) nesting. Society for ecological restoration (1): 304-310.  

THANK YOU!