EVALUATION OF EARLY DIAGENETIC INFLUENCE ON NITROGEN ISOTOPES WITHIN FOSSIL AMINO ACIDS: TOWARDS ESTIMATION OF ANCIENT FOOD WEBS AND CHEMOSYMBIOSYS

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K13584
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Stratigraphy/Paleontology
• Research Institution: Kanazawa University
• Principal Investigator: JENKINS Robert 金沢大学, 自然システム学系, 助教 (10451824)
• Research Collaborator: HAGEHASHI Daijirou ; CHIKARAISHI Yoshito ; HASEGAWA Takashi ; GOTO Akiko
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 生態系復元 / 窒素同位体比 / 殻体内有機物 / 化石 / アミノ酸 / 食物網解析

Outline of Final Research Achievements

Compound-Specific Isotope Analysis (CSIA) of nitrogen within amino acids in the fossil shells provides a solution to reconstruct paleoecosystems. However fundamental studies on this relatively new techniques hasn’t been performed yet. Thus, we use modern and fossil (800 and 6000 years ago) Turbo sazae (Gastropoda), which is presumed to be a primary consumer, i.e. its trophic level should be 2.0. Some of the modern materials were heated at 200 and 400 °C in an oven. We use the middle layer, consisting of a nacreous structure, of Turbo for this study.
The sample heated at 400 °C were partially dissolved and no amino acid was found. The other samples, with excellent shell microstructures are present, show around 1.9-2.3 for the trophic level estimated on the basis of the CSIA of amino acids. The result indicates that early diagenesis will not affect the nitrogen isotopes of amino acids in shells for at least 6000 years.

Free Research Field

古生物学