16:07 〜 16:22
[MIS16-08] Effects of environmental changes on planktic foraminiferal shells assessed by the investigation of micro-X-ray CT.
キーワード：大気二酸化炭素分圧、Globigerinoides ruber、殻密度、殻体積、サイズ正規化重量、海面水温
Ocean acidification is in progress, and the main reason of this environmental problem is that the ocean has taken in about half of pCO2 originating in human activity after the pre-industrial era. Various organisms living in the sea such as corals, coccolithophorids, and foraminifers produce their shells with carbonate ions which present in the seawaters around them. There are some evidences that the carbonate saturation state affects on the planktic foraminiferal shells, and it is known that the production rate of foraminiferal shells sensitively reacts to increasing of pCO2. The size-normalized weight of foraminiferal shells is used to estimate the surface carbonate system. However, it is unsolved that which shell parameters has been reflect to size-normalized weight. It is considered ambiguously to be attributed to shell wall thickness or shell density, or both. Therefore, it is still unclear that the relationships between foraminiferal shell parameters and environmental ones, especially three-dimensional parameters such as shell volume (which could be reflect mean shell thickness) and density.
In this study, we measured the shell size-normalized weight, shell volume, and shell density of planktic foraminifer Globigerinoides ruber (white) in the core MD98-2196 to elucidate the relationship between those shell parameters and environmental parameters (pCO2 and SST). We used high-resolution micro-X-ray computed tomography for assessed the shell volume and shell density. The results suggested that the shell size-normalized weight and shell volume might be negatively correlated to marine environmental parameters (pCO2 and SST). In addition, these two parameters might be more affected by pCO2 than SST. On the other hand, since the shell density showed no changes in 3-100ka, it could be interpreted to be constant. Thus, it is suggested that future ocean acidification and warming will cause negative effects on carbonate productivity of planktic foraminiferal even though it will not affect on shell density.
In this study, we measured the shell size-normalized weight, shell volume, and shell density of planktic foraminifer Globigerinoides ruber (white) in the core MD98-2196 to elucidate the relationship between those shell parameters and environmental parameters (pCO2 and SST). We used high-resolution micro-X-ray computed tomography for assessed the shell volume and shell density. The results suggested that the shell size-normalized weight and shell volume might be negatively correlated to marine environmental parameters (pCO2 and SST). In addition, these two parameters might be more affected by pCO2 than SST. On the other hand, since the shell density showed no changes in 3-100ka, it could be interpreted to be constant. Thus, it is suggested that future ocean acidification and warming will cause negative effects on carbonate productivity of planktic foraminiferal even though it will not affect on shell density.