Ocean acidification induces budding in larval sea urchins

Ocean acidification (OA), the reduction of ocean pH due to hydration of atmospheric C[O.sub.2], is known to affect growth and survival of marine invertebrate larvae. Survival and transport of vulnerable planktonic larval stages play important roles in determining population dynamics and community structures in coastal ecosystems. Here, we show that larvae of the purple urchin, Strongylocentrotus purpuratus, underwent high-frequency budding (release of blastula-like particles) when exposed to elevated pC[O.sub.2] level (> 700 µatm). Budding was observed in > 50% of the population and was synchronized over short periods of time (~ 24 h), suggesting this phenomenon may be previously overlooked. Although budding can be a mechanism through which larval echinoids asexually reproduce, here, the released buds did not develop into viable clones. OA-induced budding and the associated reduction in larval size suggest new hypotheses regarding physiological and ecological tradeoffs between short-term benefits (e.g. metabolic savings and predation escape) and long-term costs (e.g. tissue loss and delayed development) in the face of climate change.
Introduction Anthropogenic carbon dioxide concentration in the atmosphere (pC[O.sub.2]) has been rising and is expected to increase to 700 ppm by 2100 (Sabine et al. 2004). The world's oceans represent [...]