Paper Reviewed
Rankin, A., Seo, K., Graeve, O.A. and Taylor, J.R.A. 2019. No compromise between metabolism and behavior of decorator crabs in reduced pH conditions. Scientific Reports 9: 6262, https://doi.org/10.1038/s41598-019-42696-8.

In a recent ocean acidification experiment Rankin et al. (2019) exposed the decorator crab Pelia tumida, a species that inhabits intertidal and subtidal waters along the coasts of California and Mexico, to ambient (8.01) or reduced (7.74) pH conditions for a period of five weeks in a laboratory setting at Scripps Institution of Oceanography, San Diego, California, USA. Thereafter, the researchers measured changes in mass, exoskeleton calcification, organic content and decoration behavior so as to determine the effects of elevated pCO2 on the physiology, morphology and behavior of this marine species.

According to the authors, the results were somewhat surprising and counter to their initial hypothesis. More specifically, Rankin et al. report their study revealed "no changes at the organismal level, in terms of physiology (organic content; lipids, carbohydrates and proteins), morphology (Ca and Mg content), or behavior (decoration percent cover and mass), under reduced pH conditions." Overall, P. tumida showed "no signs of energy limitation under reduced pH conditions. Exoskeleton mineral content, body mass, and organic content of crabs remained the same across pH and decoration treatments, with no effect of reduced pH on decoration behavior."

Consequently, given the above findings, Rankin et al. conclude that "this species of decorator crab is able to maintain multiple biological processes while responding to decreases in external pH," showing "tolerance to pH levels that mimic forecasted near-term changes in ocean chemistry."