THOMAS, F.I.M.*; BADGLEY, B.D.; YUND, P.O.; GRABOWSKI, R.C.; University of South Florida; University of South Florida; University of New England; University of South Florida: Linking field measurements of hydrodynamic conditions to the fertilization of the green sea urchin Strongylocentrotus droebachiensis

The immediate transport of gametes away from free spawning invertebrates is determined by hydrodynamic conditions. In relatively benign flows gametes are retained on or near the spawning animal. In rougher flows gametes are quickly advected away from the spawning adult and diluted in the water column. Because the probability of fertilization is higher for gametes retained near the adult compared to those advected away, determining the range of flows that organisms experience in the field is essential to analyzing fertilization success in these animals. Animals are likely to spawn over a range of hydrodynamic conditions due to large scale differences in wave and current conditions and the location of specific animals relative to structural elements within the habitat. Therefore, to predict fertilization success in a location, it is necessary to link the flow conditions experienced by individuals to measurements of wave and current measurements made at larger scales. In this study, we measured the hydrodynamic conditions above adult green sea urchins, Strongylocentrotus droebachiensis and related these measures to water column measurements of velocity, turbulence, and wave height. These field measurements were then combined with laboratory data on fertilization as a function of local hydrodynamics to make predictions about the expected fertilization success of urchins under a range of hydrodynamic conditions.