Date of Award

1-1-2017

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

First Advisor

Louis Keiner

Second Advisor

Scott L. Parker

Third Advisor

H. Erin Rickard

Abstract

Sea turtle hatchlings primarily utilize sight to detect differences in elevation and light intensity present along the horizon to navigate from the nest to the water’s edge. The addition of artificial lights can cause visual misdirection, resulting in disorientation (aimlessly wandering in circular paths) or misorientation (moving in distinct paths away from ocean). Extensive research has been done on effects of high levels of artificial light but little on effects of comparatively lower levels of artificial light on hatchling sea turtle orientation. This study examined these lower intensity areas to identify if there is a threshold of artificial light above which hatchling orientation is negatively affected. During the 2016 nesting season, a Geovision GV-FER5303 non-illuminating infrared camera recorded hatchling trajectories at twenty-one loggerhead sea turtle nests from areas varying in light intensity along the Grand Strand region of South Carolina. Individual and group dynamics for lateral range of movement, orientation deviation, and average speed were measured from each nest to determine if parameters associated with orientation were significantly affected by total and artificial radiance values present at the time of emergence. Lateral range of hatchling movement is not significantly influenced under artificial or total radiance conditions; however, deviation from seaward direction (F(2,299)=43.623, p<0.001; F(3,424)=23.528, p<0.001) and average speed are (F(2,495)=42.612, p<0.001; F(3,648)=14.644, p<0.001). Deviation from brightest light source is significant under total radiance conditions (F(3,427)=11.358, p<0.001) while only marginally significant under artificial radiance conditions (F(2,300)=2.336, p=0.098). Results may help inform current management practices to enhance hatchling survival efforts near northern limit of loggerhead nesting beaches.

Download

Share

COinS