Unraveling the mystery of mass-nesting sea turtles

We use a modified syringe to squirt either ZnSO4 or saline up the nostrils of the sea turtles in our experiment. The syringe is bent at a 90 degree angle to allow us to reach both the internal and external nares of the turtle. The syringe is not used to inject anything internally, instead it is used to squirt the liquid topically into the inside of the nares.

ZnSO4 temporarily interrupts olfaction, or the sense of smell, in sea turtles without harming the turtle or affecting its behavior. This chemical is frequently used on lab rats and has previously been tested on sea turtles in operant conditioning experiments. The sea turtles in this previous experiment temporarily lost their sense of smell, with no apparent trauma or changes in behavior, and regained their full ability to smell after 1 - 5 days [Manton et al. 1972].

All of our methodology has been approved and permitted by Costa Rica (ACT-OR-DR-048-15) and the Institutional Animal Care and Use Committee of UNC-Chapel Hill (IACUC 15-220.0-A).

To apply the treatment externally, we briefly restrain the turtle to prevent it from moving and getting stabbed by the syringe while we squirt the solution into each of the nostrils.

To apply the treatment to the internal nares, we use a stick to keep the sea turtle's mouth open and briefly immobilize the sea turtle so that we can safely squirt the solution into the internal openings of the nares on the roof of the mouth (located at the bottom of the "V" shape in the upper jaw.

This entire process (internal and external) takes about two minutes. The sea turtle is kept on board the boat for a maximum of 15 minutes, with approximately ten minutes to allow the nostrils to dry initially.