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ID 117884
Title Alternative
安定同位体比による河川環境の評価
Estimation of stream ecosystems by 13C and 15N natural abundances
Author
Kohzu, Ayato Japan Science and Technology Agency
Nunokawa, Masanori Hokkaido University
Nakamura, Futoshi Hokkaido University
Keywords
fish community
lentic fish
lotic fish
oxbow lake
rehabilitation
Content Type
Journal Article
Description
Stream restoration has been conducted in the Shibetsu River in northern Japan, which aims at the recovery of its river-floodplain ecosystem altered dramatically in the last 40 years. Well-designed monitoring before and after restoration should be conducted to evaluate the effects of the stream restoration on its ecosystem. An analysis of stable isotope ratios (δ-values) is one of the most effective methods for monitoring material cycling in river ecosystems. Because product δ-values are roughly dependent upon their source δ-values, we can trace material flows by comparing the δ-values of various compounds. In the first section of this review, we introduced a basic concept of the δ-value analysis by using an analogy from various diffusion patterns of salt water. The second section described how to calculate δ-values and discussed the difference between the analyses of natural stable isotope ratios and the tracer analyses (another powerful tool for material flow analysis). The third section presented the theoretical basis of mechanisms which change the δ-values. A product δ-value becomes different from its source δ-value in two kinds of processes: isotope exchange equilibrium and kinetic isotope fractionation. The magnitude of this difference (Δδ-value: δproduct-δsource) tells us about the processes and activities of the reactions. The fourth section introduced specific examples from the carbon and nitrogen δ-values (δ13C, δ15N) of aquatic organisms to infer the degree of eutrophication and carbon recycling at ecosystem levels as well as to determine food web structures and photosynthetic activities at biological interaction levels. In the fifth section, we presented the result of our study indicating differences in food web structure between a main-stream channel and oxbow lake in the Shibetsu River watershed when their δ13C and δ15N values of diverse aquatic organisms were compared. The advantages and limitations of the stable isotope analysis in environmental assessment were also discussed.
Journal Title
Ecology and Civil Engineering
ISSN
13443755
18825974
NCID
AA11528360
Publisher
応用生態工学会
Volume
7
Issue
2
Start Page
201
End Page
213
Published Date
2005-01-30
Remark
特集:標津川再生事業の概要と再蛇行化実験の評価
Feature: Shibetsu River Restoration Project
EDB ID
DOI (Published Version)
URL ( Publisher's Version )
FullText File
language
jpn
TextVersion
Publisher
departments
Science and Technology