Turbulent Mixing and Coral Reproduction: Implications

For Instantaneous Flow Structures and Total Gametes Reaction



Abstract

One of the most common methods of reproduction in the sea is broadcast 
spawning, wherein marine invertebrates release eggs and sperm into the ambient 
flow and fertilization occurs externally. Gamete coalescence at large scales 
is dominated by fluid stirring, and may be influenced by the presence of flow 
obstructions (e.g., coral heads, bed topography). The effect of the turbulent 
wake behind a round obstacle on the second-order reaction between two 
initially distant scalars has been investigated by series of planar 
laser-induced fluorescence experiments. The scalars are released continuously, 
and are separated from each other by a lateral distance that initially impedes 
the reaction. The direct effect of the wake on mixing enhancement is 
determined by comparing segregation parameter for cases with and without the 
cylinder obstruction. A decomposition of the total reaction into mean and 
instantaneous contributions reveals that as turbulence bring filaments 
together mean processes underestimate fertilization as filaments coalesce in 
concentrations orders of magnitudes above the mean concentrations. This study 
shows that the presence of an obstacle in spawning regions may substantially 
raise the contribution of instantaneous processes up to 65%.


-- 
Farrokh Shoaei, EIT
PhD Candidate, Lab Manager
Environmental Fluid Mechanics Laboratory
CEAE, University of Colorado at Boulder
428 UCB, Boulder, CO 80309
Office: (303) 735-0404
Cell: (303) 249-8180
Email: farrokh.shoaei@colorado.edu
Web: http://www.linkedin.com/pub/farrokh-shoaei-eit/10/b56/5b0