Simultaneous analysis of delta super(13)C, delta super(15)N and delta super(34)S ratios uncovers food web relationships and the trophic importance of epiphytes in an eelgrass Zostera marina community

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...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2014-01, Vol.497, p.93-103
Main Authors: Mittermayr, Agnes, Hansen, Thomas, Sommer, Ulrich
Format: Article
Language:English
Subjects:
Zostera marina
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Summary: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 delta super(13)C values of epiphytes were close to delta super(13)C values of eelgrass, impeding a clear distinction of those 2 carbon sources, whereas seston delta super(13)C values were clearly different. This frequently encountered problem was solved by the additional use of delta super(34)S, which resulted in easily distinguishable values for sediment and seawater derived sulphur. The combination of delta super(34)C and delta super(13)C 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. delta super(15)N 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 delta super(15)N 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.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps10569