Is the relationship between body size and trophic niche position time-invariant in a predatory fish? First stable isotope evidence
Journal
PLoS ONE
Journal Volume
5
Journal Issue
2
Date Issued
2010
Author(s)
Nakazawa, Takefumi
Sakai, Yoichiro
Charbit, Alain
Koitabashi, Tadatoshi
Tayasu, Ichiro
Yamamura, Norio
Okuda, Noboru
Plaistow, Stewart
Abstract
Characterizing relationships between individual body size and trophic niche position is essential for understanding how population and food-web dynamics are mediated by size-dependent trophic interactions. However, whether (and how) intraspecific size-trophic relationships (i.e., trophic ontogeny pattern at the population level) vary with time remains poorly understood. Using archival specimens of a freshwater predatory fish Gymnogobius isaza (Tanaka 1916) from Lake Biwa, Japan, we assembled a long-term (>40 years) time-series of the size-dependence of trophic niche position by examining nitrogen stable isotope ratios (δ15N) of the fish specimens. The size-dependence of trophic niche position was defined as the slope of the relationship between δ15N and log body size. Our analyses showed that the slope was significantly positive in about 60% of years and null in other years, changing through time. This is the first quantitative (i.e., stable isotope) evidence of long-term variability in the size-trophic relationship in a predatory fish. This finding had implications for the fish trophic dynamics, despite that about 60% of the yearly values were not statistically different from the long-term average. We proposed hypotheses for the underlying mechanism of the time-varying size-trophic relationship. © 2010 Nakazawa et al.
Other Subjects
stable isotope; fresh water; nitrogen; animal experiment; article; body size; controlled study; ecological niche; fish; food web; freshwater fish; Japan; lake; molecular dynamics; nonhuman; ontogeny; predator; time series analysis; trophic level; trophic niche position; animal; biological model; feeding behavior; food chain; Perciformes; physiology; predation; time; Gymnogobius isaza; Animals; Body Size; Feeding Behavior; Food Chain; Fresh Water; Japan; Models, Biological; Nitrogen Isotopes; Perciformes; Predatory Behavior; Time Factors
Type
journal article