Ocean Acidification

Although it is widely believed that seawater is chemically well-buffered, CO2-induced acidification of the world’s oceans threatens the viability of many species [1–3]. Research to date has focused on the responses of adult stages of calcifying taxa to gross pH changes relevant for the years 2200–2400 [3,4]. We investigated the consequences of exposure of gametes and larvae of the sea urchin Heliocidaris erythrogramma to CO2-induced acidification by –0.4 pH units (the
upper limit of predictions for the year 2100 [5]), and found statistically
significant reductions in sperm swimming speed and percent sperm motility. We predicted the effects of these changes using an established model [6], and tested fertilization success experimentally in assays using the same gametes and pH
treatments. Observed reductions in fertilization success corresponded closely to model predictions (24% reduction). If general, these findings have important implications for the reproductive and population viability of broadcast spawning marine species in the future acidified ocean.



Havenhand J. N., Buttler F.-R., Thorndyke M. C., & Williamson J. E., 2008. Near-future levels of ocean acidification reduce fertilization success in a sea urchin. Current Biology 18(5): 651-652. Article.