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Student Research Projects

Assessment of Swimming Performance in Loggerhead Sea Turtle (Caretta caretta) Yearlings: Kinematic and Respiratory Analysis

Student Jeremiah Clester, ‘13
Faculty Mentor(s) Dr. Soraya Bartol
Department Biology
Course BIO 489: Independent Research

Abstract

Sea turtles have adapted to aquatic locomotion by modifying the form of both their body and flippers. These modifications include an elongated streamlined shell, a non-retractable neck, and enlarged semi-rigid foreflippers that serve as biofoils, i.e., underwater wings. Loggerhead sea turtles use three modes of swimming, including “dogpaddling” and “rear flipper kicking” (both drag-based propulsion) and “powerstroking” (lift-based propulsion). While these modes have been described qualitatively, the kinematics of these modes have not been quantified as a function of swimming speed and little is known about the respiratory physiology of sea turtles during swimming. For this study, we studied the kinematics of yearling loggerhead sea turtles to quantify their swimming movements and recorded breathing patterns to understand oxygen requirements during swimming. We swam 4 C. caretta yearlings (include size range) from the Virginia Aquarium in a water tunnel at Old Dominion University, which has a 38 x 50 x 150 cm test section (model 1520, Rolling Hills Research Corporation), at speeds of 5-40 cm s-1. While swimming, turtles were filmed using 3 high-speed DALSA Falcon digital video cameras (1600 x 1200 pixel resolution) triggered at 100 fps, which provided lateral, ventral, and rear views of the swimming turtles. Data were captured with a Streams 5 (IO Industries) digital video capture system and analyzed using Image J. For this study, we measured flipper amplitude, flipper speed, recoil motions, and respiration rate for each speed interval and recorded maximum swimming speed of the yearlings. An increase in both flipper amplitude and flipper speed was observed with swimming speed. Maximum swimming speed was recorded at 35 cm s-1, or approximately 1.5 body length s-1. We did not record an increase in rate of breathing with speed, rather we found that these animals increased the intervals between surface breaths with increased swimming speed. While unexpected, this observation may reflect an elevated drag cost, as the turtles need to pitch their bodies and withstand exponentially more drag at high speeds while swimming to the surface than at low speeds. Consequently, turtles may only come to surface when absolutely necessary at high speeds to reduce this drag penalty.

 

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