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Hartford, Jillian R ¹ ; Crimaldi, John P ²

¹ University of Colorado--Boulder
² University of Colorado--Boulder

Various benthic invertebrates (e.g. sea urchins, anemones, corals) rely on broadcast spawning, a fertilization strategy whereby male and female adults simultaneously release sperm and egg into the surrounding flow [1]. In order for the fertilization reaction to occur, the two scalars, sperm and egg (gametes), are brought together via turbulent stirring, molecular diffusion, and sperm taxis. Several numerical modeling approaches are used to investigate the role of turbulent stirring processes on fertilization efficiency in broadcast spawning. A particle-tracking model was used in combination with various types of vortex flows to investigate how stirring and mixing processes influence the fate and distribution of two initially distinct gamete sets. The subsequent fertilization rate depends on the product of co-occurring egg and sperm concentrations [2]. The results indicate that vortex structure imposes spatial correlation on initially non-overlapping gamete sets, which increases potential fertilization rates. Fertilization enhancement is primarily dependent on the Peclet number and is robust to the initial placement of the gametes. Both single vortex and multiple vortex cases are considered and the gametes are treated as reactive species. Together, the models provide insight into the physical mechanisms that enhance fertilization.

[1] D. Levitan, Ecology of Marine Invertebrate Larvae, CRC Press, Boca Raton, 123-156, 1995.

[2] J.P. Crimaldi and H.S. Browning, “A proposed mechanism for turbulent enhancement of broadcast spawning efficiency,” Journal of Marine Systems. 49(1-4), 3-18, 2004.