Hydrodynamic effect of a satellite transmitter on a juvenile green turtle (Chelonia mydas)

Area of Science:

• Marine Biology
• Animal Biologging
• Fluid Dynamics

Background:

• Satellite transmitters are crucial for tracking marine animals like green turtles (Chelonia mydas).
• The hydrodynamic impact of these transmitters on turtle swimming performance is not well understood.

Purpose of the Study:

• To quantify the aerodynamic and hydrodynamic effects of a satellite transmitter on a juvenile green turtle.
• To provide design recommendations for minimizing drag and improving the efficiency of turtle-borne transmitters.

Main Methods:

• Wind tunnel experiments were conducted using a scaled model of a green turtle with and without a transmitter.
• Measurements included drag, lift, and pitch moment across various speeds and flow angles.
• Data were scaled to estimate effects in the marine environment.

Main Results:

• The transmitter increased drag by 27-30% and pitch moment by 11-42% at typical swimming angles.
• Lift was reduced by less than 10%.
• Estimated swimming speed reduction of 11% due to increased drag.

Conclusions:

• Satellite transmitters significantly impair the hydrodynamic performance of green turtles.
• Design modifications can mitigate adverse effects, improving tracking efficiency and minimizing energetic costs for turtles.