Student Research Projects

Effects of Acidified Sea Water on the Shell Morphology of Juvenile Crassostrea virginica

Student Lindsay Dade, '16
Faculty Mentor(s)
Department Biology
Course Biology 489: Research in the Natural Sciences

Abstract

Bivalves have a shell composed of calcium carbonate and are at risk of dissolution due to increasingly acidic ocean waters from dissolved carbon dioxide. In this study I examined the effects of acidified seawater on the shell morphology of juvenile Crassostrea virginica. I used a phosphate buffer to lower the pH to 6.6 and 6.0, with a control pH of 7.4. After a 14 d exposure to the respective pH treatments, the oysters were removed, mounted, and observed using the Scanning Electron Microscope to determine any shell deformations. Three specific areas of the shell were observed for changes in morphology: shell surface, shell edge and prism structure. By comparing the structure and texture of the prismatic layer on the ventral shells, it was observed that both lower pH treatments had increased porosity, less defined prisms with larger gaps in between, and more crumbling of the calcite columns. The shell edge in both treatments was thinner and showed signs of erosion. Increased porosity observed in this study is consistent with that observed for other bivalve species Argopecten irradians, Mercenaria mercenaria and Saccostrea glomerata at a higher pH of 7.5. Shell morphology in Crassostrea virginica, however, appears to be unaffected by higher pH levels and may be better acclimated to this environment.

Grants

Virginia Wesleyan Undergraduate Research Grant for Research, 2015-16