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Tracking the flow of bacterially derived 13 C and 15 N through soil faunal feeding channels
Author(s) -
Crotty F. V.,
Blackshaw R. P.,
Murray P. J.
Publication year - 2011
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4945
Subject(s) - decomposer , trophic level , soil food web , food web , ecology , soil biology , chemistry , biology , soil water , ecosystem
The soil food web has been referred to as a ‘black box’, a ‘poor man's tropical rainforest’ and an ‘enigma’, due to its opacity, diversity and the limited insight into feeding specificity. Here we investigate the flow of C and N through the soil food web as a way to gain understanding of the feeding interactions occurring. A bacterium, Pseudomonas lurida , was introduced to soil cores from two different habitats, a grassland and a woodland with the same soil type, enriched to 99 atom% in 13 C and 15 N, to trace the flow of bacterial C and N through the soil food web. Throughout the experiment the soil remained enriched in 13 C and 15 N. Almost all the invertebrates tested gained C and N enrichment indicative of the labelled bacteria, implying that bacterial feeding is a common mechanism within the soil. Only three groups were significantly enriched in both 13 C and 15 N in both habitats. These were Collembola (Entomobryomorpha), Acari (Oribatida), and Nematoda, indicating that these organisms are consuming the most bacteria within both systems. When the invertebrates were grouped into hypothesised trophic levels, those considered secondary decomposers were gaining the most enrichment across all invertebrates tested. This enrichment was also high in the micro‐predators within the soil, implying that their main food source was the secondary decomposers, particularly the Collembola. Using an enriched bacterium to track the trophic transfer between organisms within the soil food web is a novel way of empirically showing that interactions are occurring, which normally cannot be seen. Copyright © 2011 John Wiley & Sons, Ltd.