Japan Geoscience Union Meeting 2014

Presentation information

Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS21_28AM2] Biogeochemistry

Mon. Apr 28, 2014 11:00 AM - 12:45 PM 511 (5F)

Convener:*Muneoki Yoh(Tokyo University of Agriculture and Technology), Hideaki Shibata(Field Science Center fot Northern Biosphere, Hokkaido University), Naohiko Ohkouchi(Japan Agency for Marine-Earth Science and Technology), Youhei Yamashita(Faculty of Environmental Earth Science, Hokkaido University), Chair:Yoshinori Takano(Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)), Seiya Nagao(Institute of Nature and Environmental Technology, Kanazawa University), Ichiro Tayasu(Center for Ecological Research, Kyoto University), Tomoya Iwata(Faculty of Life and Environmental Sciences, University of Yamanashi)

12:00 PM - 12:15 PM

[MIS21-P01_PG] A metabolic model of stable isotope dynamics

3-min talk in an oral session

*Reiichiro ISHII1, Maki NOGUCHI1, Eitaro WADA1 (1.JAMSTEC)

Carbon and nitrogen stable isotope analysis have been a powerful tool used for identifying food-web structures. Our recent study suggested that the ratios of trophic fractionation of carbon and nitrogen isotopes (∆δ15N/∆δ13C) throughout food chain are similar in various ecosystems (Wada et al. 2013), although the general mechanisms determining isotopic incorporation rates and discrimination factors are poorly understood. Here, we developed a mechanistic model of the isotopic fractionation in metabolic processes that are common to animals composing most grazing food chains. Particularly, we calculate fluxes of carbon and nitrogen stable isotopes within an organism by following fluxes of molecules involved in some of physiological reactions: the synthesis of amino acids and their carbon skeletons, the rates of which are governed by energy-producing systems such as glycolysis, the TCA cycle, and oxidative phosphorylation, that is, the ratio of the rate of amino-acid syntheses to that of energy-yielding processes. The active metabolic pathways above are assumed to be changed by the conditions of supply (diet quantity and quality) and demand (growth rate). The model result suggests that the instant isotopic composition of animals are sensitive to the change of their diet composition and growth rate, but on the other hand, the isotopic composition converges as the integrating period becomes long. With further temporal scaling-up, in turn, the isotopic compositions of animal body reflect the spatio?temporal variability due to their life history, migration and foraging patterns. This gives mechanistic insight to what information we can acquire from the observation.