Using Nano-Computerized Tomography Imaging and 3D modeling to Quantitatively Observe the Response of Modern Mediterranean Pteropods to Ocean Acidification

An effect of anthropogenic increase in carbon dioxide levels is ocean acidification, which has been reported to have an impact on the effective growth rate of marine calcifiers, key components in the oceanic carbon cycle. Previous analysis methods on the effects of increasing pH levels on the shells of marine calcifiers include weight measurements and observations of outer shell structures and drew qualitative conclusions. However, these methods have limited quantitative applicability and do not distinguish between organic matter and the actual calcium carbonate shell.

Computerized tomography (CT) imaging technology has traditionally been used for medical and engineering purposes but has recently been applied to fields such as geology. The advantage of using such a method is that X-rays can produce a large number of 2D slices, which are assembled as a final 3D model of the sample. A sub-micrometer scale computerized tomography (nano-CT) technology, with a voxel resolution of <300 nm possible, will be used to generate a 3D model of the samples and shell thickness, volume, and density measurement will be done on a volume analysis software program.We will apply this method to two Mediterranean pteropod species collected in a 1910 and a recent cruise. In addition to these samples, volume analysis will also be done on larval bivalve mollusks cultured at different pH levels. By using this new method of analysis, we may be able to quantify changes in calcification due to ocean acidification in these historical samples and cultured marine organisms.