Inter-Research > MEPS > v497 > p93-103  

MEPS 497:93-103 (2014)  -  DOI: https://doi.org/10.3354/meps10569

Simultaneous analysis of δ13C, δ15N and δ34S ratios uncovers food web relationships and the trophic importance of epiphytes in an eelgrass Zostera marina community

Agnes Mittermayr*, Thomas Hansen, Ulrich Sommer

GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbooker Weg 20, 24105 Kiel, Germany
*Corresponding author:

ABSTRACT: Simultaneous analysis of carbon, nitrogen and sulphur stable isotope ratios was applied in this pilot study to examine the food web of a Zostera marina L. system in the western Baltic Sea. Samples of 3 potential food sources: eelgrass, epiphytic algae and seston, as well as 69 consumer species were collected during the growing season of Z. marina from March to September 2011. The measured δ13C values of epiphytes were close to δ13C values of eelgrass, impeding a clear distinction of those 2 carbon sources, whereas seston δ13C values were clearly different. This frequently encountered problem was solved by the additional use of δ34S, which resulted in easily distinguishable values for sediment and seawater derived sulphur. The combination of δ34S and δ13C values made a separation of carbon sources possible and enabled the allocation of potential food sources to consumers and a description of their trophic relationships. The results of stable isotope ratio analysis of this eelgrass community strongly indicate a food web based on epiphyte and seston production. δ15N values show a food web consisting of large numbers of generalists and a high degree of omnivory amongst the consumer species analysed. This implies an occupation of every trophic position possible, which is supported by an even distribution of δ15N values. Previously described eelgrass food webs may have to be re-evaluated by considering sulphur stable isotope ratios in order to provide a clear picture on primary carbon sources.


KEY WORDS: Stable isotopes · Food web · Seagrass · Epiphytes · Trophic level


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Cite this article as: Mittermayr A, Hansen T, Sommer U (2014) Simultaneous analysis of δ13C, δ15N and δ34S ratios uncovers food web relationships and the trophic importance of epiphytes in an eelgrass Zostera marina community. Mar Ecol Prog Ser 497:93-103. https://doi.org/10.3354/meps10569

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