Meeting Abstract
104.3 Thursday, Jan. 7 Diffusive and conductive effects of sand on gas exchange in sea turtle nests O’CONNOR, M.P.*; SUSS, J.; SOTHERLAND, P.R.; SPOTILA, J.R.; Drexel Univ.; Drexel Univ.; Kalamazoo Coll.; Drexel Univ. mike.oconnor@drexel.edu
Sea turtles bury their nests deeply (25-100 cm) in beach sand, thus limiting nest predation and extremes of thermal and hydric conditions. But the sand overlying the nest can also limit respiratory gas exchange with the atmosphere. Empirical data suggest that the induced hypoxia affects egg metabolism, development times, and hatching success. Models indicate that tidally induced nest ventilation, the geometry of the nest, and nest density can all affect nest O 2 and CO 2 concentrations. Here we concentrate on the relative importance of diffusive (driven by gas concentration gradients) and convective (bulf flows driven by pressure gradients) limitations on nest respiration. Although sand structure can affect both diffusion and convection, interstitial water in the sand can affect convection and diffusion differently. Our models suggest that although convection can affect nest gas concentrations to some extent, diffusive resistances largely determine nest O 2 and CO 2 concentrations. We also examine sand structure from a series of loggerhead turtle nesting beaches for potential differences in resistance to convection and diffusion. Sand grain size distributions varied significantly among the beaches examined, particularly for grain sizes ranging from 0.1-2 mm. Resulting predicted diffusive and convective resistances to gas flux also varied among beaches.
