By Heather Hoffman, 2013 BHI Conservancy Intern

1. BEACH NOURISHMENT AND ITS
EFFECT ON SEX DETERMINATION
OF LOGGERHEAD HATCHLINGS
Heather Hoffmann
Sea Turtle Intern at Bald Head Island
Conservancy

2. BACKGROUND
¢ Temperature dependent sex determination
¢ Thermosensitive period
— 7-15 days in middle third of incubation
¢ Hormones in TSD systems
— Aromatase enzyme affected by temperature

3. BACKGROUND
¢ Bald Head Island
— Northern nesting point
¢ Beach nourishment becoming a problem
— Effect on male to female ratio?
¢ Human impact on endangered species

4. 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.

5. 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?

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

7. 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

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

9. 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.

10. THANK YOU!