Thousands of research studies describe the effects of ocean acidification on marine organisms. These empirical studies conducted over the last decade concentrate primarily on biological responses to tightly-controlled and constant levels of marine carbonate chemistry conditions, and provide information for understanding species responses to mean changes. However, as discussed recently in the literature, the lack of realism in experimental designs have led to questions and concerns about how laboratory studies can be extrapolated to the field. We are missing information on the role ocean acidification will play in natural environments that are at once highly dynamic and changing in complex ways. To more accurately inform predictions of future changes, we need to know how organisms tolerate mean conditions altered by global change, and the role of variance. Our study examined the effects of temporally-varying carbonate chemistry exposure regimes on the physiological responses of the articulated, coralline algae, Corallina vancouverensis.
We found that while calcification rates declined linearly with decreasing saturation states, rates in variable conditions were lower than those from static conditions even though the total time spent in unfavorable chemistry was equal across treatments. Our results illustrate that incorporating natural environmental fluctuations across a range of frequencies in empirical studies can result in different outcomes than biological manipulation experiments performed in static conditions.