Interspecific and nutrient-dependent variations in stable isotope fractionation

Experimental studies simulating pelagic multitrophic systems

N. Aberle, A. M. Malzahn

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Stable isotope signatures of primary producers display high inter- and intraspecific variation. This is assigned to species-specific differences in isotope fractionation and variable abiotic conditions, e.g., temperature, and nutrient and light availability. As consumers reflect the isotopic signature of their food source, such variations have direct impacts on the ecological interpretation of stable isotope data. To elucidate the variability of isotope fractionation at the primary producer level and the transfer of the signal through food webs, we used a standardised marine tri-trophic system in which the primary producers were manipulated while the two consumer levels were kept constant. These manipulations were (1) different algal species grown under identical conditions to address interspecific variability and (2) a single algal species cultivated under different nutrient regimes to address nutrient-dependent variability. Our experiments resulted in strong interspecific variation between different algal species (Thalassiosira weissflogii, Dunaliella salina, and Rhodomonas salina) and nutrient-dependent shifts in stable isotope signatures in response to nutrient limitation of R. salina. The trophic enrichment in 15N and 13C of primary and secondary consumers (nauplii of Acartia tonsa and larval herring) showed strong deviations from the postulated degree of 1.0‰ enrichment in δ13C and 3.4‰ enrichment in δ15N. Surprisingly, nauplii of A. tonsa tended to keep "isotopic homeostasis" in terms of δ15N, a pattern not described in the literature so far. Our results suggest that the diets' nutritional composition and food quality as well as the stoichiometric needs of consumers significantly affect the degree of trophic enrichment and that these mechanisms must be considered in ecological studies, especially when lower trophic levels, where variability is highest, are concerned.

Original languageEnglish
Pages (from-to)291-303
Number of pages13
JournalOecologia
Volume154
Issue number2
DOIs
Publication statusPublished - Nov 2007

Fingerprint

isotope fractionation
stable isotopes
stable isotope
experimental study
fractionation
interspecific variation
nutrient
nutrients
Acartia tonsa
nauplii
isotope
nutrient limitation
light availability
food quality
intraspecific variation
homeostasis
Dunaliella salina
Rhodomonas
nutrient availability
trophic level

Keywords

  • Clupea harengus
  • Food quality
  • Food-web studies
  • Homeostasis
  • Trophic interactions

ASJC Scopus subject areas

  • Ecology

Cite this

Interspecific and nutrient-dependent variations in stable isotope fractionation : Experimental studies simulating pelagic multitrophic systems. / Aberle, N.; Malzahn, A. M.

In: Oecologia, Vol. 154, No. 2, 11.2007, p. 291-303.

Research output: Contribution to journalArticle

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