Meeting Abstract

56.3  Jan. 6  Position, distance and hydrodynamic effects on fertilization success of the green sea urchin Strongylocentrotus droebachiensis. KREGTING, L.T*; YUND, P.O; THOMAS, F.I.M; GRABOWSKI, R.C; University of New England; University of New England; University of Hawaii; University of South Florida lkregting@une.edu

The distance and location between free spawning invertebrates such as sea urchins can have important implications on fertilization success and where fertilization occurs (on the substratum or aboral surface, or in the water column). The high viscosity of male spawn may reduce the rate of diffusion from a sperm mass, thus increasing the longevity of sperm and providing a steady supply of viable sperm up to several meters downstream of the male. Fertilization is generally assumed to be unlikely if a female is upstream of a male, but negatively buoyant eggs can become entrained and fertilized in the eddy downstream of a male. In this study, we quantified the percentage of eggs fertilized on or near sea urchins and in the water column as a function of water velocity, distance, and position of the male relative to the female for the green urchin, Strongylocentrotus droebachiensis. Fertilization decreased with velocity, and eggs were fertilized in different locations under different conditions; the substratum was an important site for fertilization under a broad range of conditions. In contrast to previous studies, we found that fertilization in some locations did not decrease rapidly with distance, and that fertilization in substratum samples was still fairly high even when the female released eggs upstream of the male.