Good News for Earth Day: A Negative Result from Ocean Acidification

In 2012, Stanford’s Daniele Fanelli published a provocative paper, “Negative Results are Disappearing in Most Disciplines and Countries” in the prestigious about-science journal Scientometrics. It demonstrated a remarkable increase in the number of papers reporting “positive” results, meaning those that found data in support of a prior hypothesis.

The reasons are manifold and in part to do with the way that we fund science. Research proposals usually include some statements of hypotheses that serve as the rationale for funding. For example, one might hypothesize that global warming will increase heat-related death, reduce crop yields, or cause wars. And, almost always, the funded scientists will find evidence to support each hypothesis.

Part of this has to do with the way agencies dole out the dough. There’s usually a meeting of five or so folks who wade through maybe a hundred proposals. There’s general discussion about which ones are worth funding, often centering around objectives and hypotheses. Upon funding, research that does not support a funded hypothesis will threaten a grant renewal.

“Ocean Acidification” will be, in our humble opinion, the next in a long line of ends-of-the-worlds that we have come to be used to. Global cooling, acid rain, stratospheric ozone depletion, tropospheric ozone increases, and global warming come to mind, in sequential order, soon to be followed by ocean acidification as our environmentalist friends become frustrated with any real meaningful policies to forestall our heretofore torpid warming.

Oddly enough, there are vast areas of the central Atlantic and Pacific oceans with naturally very low pH, or relative acidity, compared to the rest of the sea, and their relative acidity changes are large, compared to any small changes that humans have foisted on the ocean. Given that there’s often considerable biodiversity in these regions, isn’t it odd that virtually all research findings show ocean acidification to be deleterious? Kloekel (2010) performed a meta-analysis of nearly 600 findings and found approximately 97% deleterious results. That only 3% were salutary seems odd on a world where ocean pH naturally varies so much.

A recent “exception” was just published—deVries et al. (2016) in Scientific Reports. They set out to “examine the long-term effects of moderate increases in pCO2 and temperature” on the stress physiology and the hard exoskeleton of shrimp. It is a standard meme that decreasing pH, in general, is bad for hard-shelled organisms. They varied the pH and the temperature in a controlled laboratory setting. The working hypothesis was that lowered pH (more “acidic”) along with high temperature would elicit a stress response and render the shell more brittle.

Didn’t happen. Contrary to their initial thinking, the mantis shrimp exhibited an “apparently large tolerance range for changes in environmental pH and temperature.” More specifically, they found that “N. bredini showed no changes in growth, molting, enzymatic and protein indicators of oxidative stress, exoskeleton morphology, calcium content, or mechanical properties in response to experimental pH and temperature stressors,” which findings, in their words, suggest “that this species has evolved compensation mechanisms to cope with significant environmental change.” And if this one species has developed compensation mechanisms, it is not an illogical stretch to assume that other intertidal species have done so too.

Consequently, alarmist concerns for the future well-being of marine life in response to the twin evils of ocean acidification and warming are tempered (again) by observations showing that life tends to find a way to cope with the many challenges it faces.

 

References:

deVries, M.S., Webb, S.J., Tu, J., Cory, E., Morgan, V., Sah, R.L., Deheyn, D.D. and Taylor, J.R.A. 2016. Stress physiology and weapon integrity of intertidal mantis shrimp under future ocean conditions. Scientific Reports 6: 38637, DOI:10.1038/srep38637.

Kroeker, K.J., et al, 2010. Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms.  Ecology Letters, (2010) 13: 1419–1434 doi: 10.1111/j.1461-0248.2010.01518.x