Document Detail

Stable isotopes, beaks and predators: a new tool to study the trophic ecology of cephalopods, including giant and colossal squids.
MedLine Citation:
PMID:  16048776     Owner:  NLM     Status:  MEDLINE    
Cephalopods play a key role in the marine environment but knowledge of their feeding habits is limited by lack of data. Here, we have developed a new tool to investigate their feeding ecology by combining the use of their predators as biological samplers together with measurements of the stable isotopic signature of their beaks. Cephalopod beaks are chitinous hard structures that resist digestion and the stable isotope ratios of carbon (delta13C) and nitrogen (delta15N) are indicators of the foraging areas and trophic levels of consumers, respectively. First, a comparison of delta13C and delta15N values of different tissues from the same individuals showed that beaks were slightly enriched in 13C but highly impoverished in 15N compared with lipid-free muscle tissues. Second, beaks from the same species showed a progressive increase in their delta15N values with increasing size, which is in agreement with a dietary shift from lower to higher trophic levels during cephalopod growth. In the same way, there was an increase in the delta15N signature of various parts of the same lower beaks in the order rostrum, lateral walls and wings, which reflects the progressive growth and chitinization of the beaks in parallel with dietary changes. Third, we investigated the trophic structure of a cephalopod community for the first time. Values of delta15N indicate that cephalopods living in slope waters of the subantarctic Kerguelen Islands (n=18 species) encompass almost three distinct trophic levels, with a continuum of two levels between crustacean- and fish-eaters and a distinct higher trophic level occupied by the colossal squid Mesonychoteuthis hamiltoni. delta13C values demonstrated that cephalopods grow in three different marine ecosystems, with 16 species living and developing in Kerguelen waters and two species migrating from either Antarctica (Slosarczykovia circumantarctica) or the subtropics (the giant squid Architeuthis dux). The stable isotopic signature of beaks accumulated in predators' stomachs therefore revealed new trophic relationships and migration patterns and is a powerful tool to investigate the role of the poorly known cephalopods in the marine environment.
Yves Cherel; Keith A Hobson
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Proceedings. Biological sciences / The Royal Society     Volume:  272     ISSN:  0962-8452     ISO Abbreviation:  Proc. Biol. Sci.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-28     Completed Date:  2005-11-21     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  101245157     Medline TA:  Proc Biol Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  1601-7     Citation Subset:  IM    
Centre d'Etudes Biologiques de Chizé, UPR 1934 du CNRS, BP 14, 79360 Villiers-en-Bois, France.
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MeSH Terms
Animal Migration
Atlantic Ocean
Beak / metabolism*
Carbon Isotopes / metabolism
Decapodiformes / metabolism,  physiology*
Ecology / methods*
Feeding Behavior / physiology*
Food Chain*
Nitrogen Isotopes / metabolism
Species Specificity
Reg. No./Substance:
0/Carbon Isotopes; 0/Nitrogen Isotopes

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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