Dissertation Research: Dynamics of Fertilization: Ecological Consequences of Flow on Sperm-egg Interactions

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Dissertation Research: Dynamics of Fertilizations: Ecoological Consequences of Flow on Sperm-egg InteractionsDr. Richard K. Zimmer & Jeffrey A. RiffellFor marine animals that broadcast spawn, the turbulent nature of the ocean environment into which the gametes are released can drastically influence successful fertilization. Water motion can transport and mix the gametes together, facilitating commingling between sperm and eggs, or it can have a detrimental effect by causing rapid dilution and prevention of sperm-egg encounters. Although flow has long been recognized as a critical factor influencing fertilization, at the scale of the gametes, little is known about the influence of sperm behavior and fluid motion on mediating gamete encounters. To understand the importance of gamete behavior and fluid motion on fertilization, controlled laboratory studies under simulated natural environmental conditions are necessary and vital. Using the red abalone (Haliotis rufescens) as the model organism for exploring fertilization dynamics, this study will establish the influence of gamete behavior, concentration, and fluid motion on sperm-egg interactions. This will be accomplished through three phases of this project: (i) Subtidal surveys will census adult abalone populations and flow measurements will be taken to characterize aspects of the hydrodynamic environment within typical abalone habitat (subtidal kelp beds), allowing us to scale our laboratory flow-tank experiments, (ii) laboratory flow tank experiments will examine the influence of turbulence (shear) and gamete concentration on fertilization, and (iii) sperm chemosensory-mediated behavior will be examined under simulated natural flow conditions. Fertilization has been implicated as an important factor regulating population dynamics in many animals, particularly in marine organisms that broadcast their sperm and eggs into the sea. Along the western coast of the United States, abalones are commercially valuable but ecologically endangered resource. By providing new information on physical and behavioral mechanisms mediating fertilization success, this study should have significant implications for managing and restoring threatened abalone populations.