Our understanding of the effects of ocean acidification on whole organism function is growing, but most current information is for adult stages of development. Here, we show the effects of reduced pH seawater (pH 7.6) on aspects of the development, physiology and behaviour of encapsulated embryos of the marine intertidal gastropod Littorina obtusata. We found reduced viability and increased development times under reduced pH conditions, and the embryos had significantly altered behaviours and physiologies. In acidified seawater, embryos spent more time stationary, had slower rotation rates, spent less time crawling, but increased their movement periodicity compared with those maintained under control conditions. Larval and adult heart rates were significantly lower in acidified seawater, and hatchling snails had an altered shell morphology (lateral length and spiral shell length) compared to control snails. Our findings show that ocean acidification may have multiple, subtle effects during the early development of marine animals that may have implications for their survival beyond those predicted using later life stages.

Note from the author "The pH was measured in NBS scale, also the measures of pH and pCO2 are not coupled. The pCO2 was taken from the display on the output of the LiCOR machine used to control the gas mix. Therefore it is a single value which was recorded a number of times throughout the day (more as a way of making sure the gas supply was stable). Conversely the pH was measured in the 15 replicate experimental pots on a single occasion each day of the experiment to give an understanding of the conditions in experimental pots. Unfortunately a second parameter of the seawater carbonate chemistry was not noted directly from the pots, just pH, temperature and salinity. Therefore it is difficult to parameterise the carbonate system fully, particularly as we do not have the reciprocal pCO2 values for the ambient treatment."

Supplement to: Ellis, Robert P; Bersey, Jess; Rundle, Simon; Hall-Spencer, Jason M; Spicer, John I (2009): Subtle but significant effects of CO2 acidified seawater on embryos of the intertidal snail ,Littorina obtusata. Aquatic Biology, 5(1), 41-48