A continuous challenge in ecology is to estimate and predict trophic structures in complex food webs. Knowledge on trophic interactions is crucial for our understanding of energy pathways, predations and feeding patterns in ecosystems.

Analysis of amino acid  stable nitrogen isotope ratios is a relatively new and powerful technique for estimating trophic position of organisms.  One of the primary advantages of this method, compared to common bulk stable isotopes, is that the stable nitrogen isotope ratios of some amino acids measured in a consumer’s tissue are very similar to the primary producers at the base of the food web, while the  stable nitrogen isotope ratios of other amino acids increase with each trophic position.

In the paper, Jens and co-authors present the first meta-analysis of stable nitrogen isotope ratios of amino acids from measurements of 359 marine species covering four trophic levels for predicting species trophic position. This study clarifies the advantages and limitations of using stable nitrogen isotope ratios of amino acids as a tool in trophic ecology and provides a guideline for future application of this technique in food web studies.

You will find the article at: http://link.springer.com/article/10.1007/s00442-015-3305-7