Impacts of Ocean Acidification on the sand dollar, Dendraster excentricus Fertilization Success and Early Development

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Date
2012-10Author
Villalobos, Cristina
Grunbaum, Danny
Chan, Kit Yu
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Ocean acidification (OA), a result of increased atmospheric CO2, is predicted to decrease
the surface ocean pH by a value of 0.4 units by the year 2100. Decreases in pH have been
shown to cause deleterious effects on many calcifying marine organisms, which may
negatively affect ecosystem functions. Few studies, however, have investigated OA
impacts on fertilization success of free-spawning marine organisms. This study focuses
on the effects of OA on fertilization success in the sand dollar Dendraster
excentricus. The goal of this study is to experimentally determine whether decreases in
pH values lower fertilization success in D. excentricus. The two-pH treatments chosen for
this experiment reflect the present day pH value (8.1) and the predicted pH value by the
IPPC for the year 2100 (7.7). Gametes from adult D. excentricus collected from Crescent
Bay, East Sound, Orcas Island, WA, were fertilized in filtered seawater with pH 8.1 and
7.7. Fertilization success was determined by the percentage of 2 and 4-cell cleaving
embryos. A numerical model of reproductive success as a function of adult density and
current conditions will be used to assess potential population-level effects of observed
changes in fertilization success. Results of this investigation will aid future studies on the
effects of climate change on marine organisms and ecological stability of marine
communities.