Global Trophic Position Comparison of Two Dominant Mesopelagic Fish Families

The [delta].sup.15 N values of organisms are commonly used across diverse ecosystems to estimate trophic position and infer trophic connectivity. We undertook a novel cross-basin comparison of trophic position in two ecologically well-characterized and different groups of dominant mid-water fish con...

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Bibliographic Details
Published in:PloS one 2012-11, Vol.7 (11), p.e50133
Main Authors: Choy, C. Anela, Davison, Peter C, Drazen, Jeffrey C, Flynn, Adrian, Gier, Elizabeth J, Hoffman, Joel C, McClain-Counts, Jennifer P, Miller, Todd W, Popp, Brian N, Ross, Steve W, Sutton, Tracey T
Format: Article
Language:English
Subjects:
Biogeochemistry
Ecosystems
Nitrogen (Chemical element)
Pelagic zone
Phenylalanine
Water wells
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Summary:The [delta].sup.15 N values of organisms are commonly used across diverse ecosystems to estimate trophic position and infer trophic connectivity. We undertook a novel cross-basin comparison of trophic position in two ecologically well-characterized and different groups of dominant mid-water fish consumers using amino acid nitrogen isotope compositions. We found that trophic positions estimated from the [delta].sup.15 N values of individual amino acids are nearly uniform within both families of these fishes across five global regions despite great variability in bulk tissue [delta].sup.15 N values. Regional differences in the [delta].sup.15 N values of phenylalanine confirmed that bulk tissue [delta].sup.15 N values reflect region-specific water mass biogeochemistry controlling [delta].sup.15 N values at the base of the food web. Trophic positions calculated from amino acid isotopic analyses (AA-TP) for lanternfishes (family Myctophidae) (AA-TP ~2.9) largely align with expectations from stomach content studies (TP ~3.2), while AA-TPs for dragonfishes (family Stomiidae) (AA-TP ~3.2) were lower than TPs derived from stomach content studies (TP~4.1). We demonstrate that amino acid nitrogen isotope analysis can overcome shortcomings of bulk tissue isotope analysis across biogeochemically distinct systems to provide globally comparative information regarding marine food web structure.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0050133