title: Trophic structure in a seabird host-parasite food web: insights from stable isotope analyses.
abstract: Ecological studies on food webs rarely include parasites, partly due to the complexity and dimensionality of host-parasite interaction networks. Multiple co-occurring parasites can show different feeding strategies and thus lead to complex and cryptic trophic relationships, which are often difficult to disentangle by traditional methods. We analyzed stable isotope ratios of C ((13)C/(12)C, delta(13)C) and N ((15)N/(14)N, delta(15)N) of host and ectoparasite tissues to investigate trophic structure in 4 co-occurring ectoparasites: three lice and one flea species, on two closely related and spatially segregated seabird hosts (Calonectris shearwaters). delta(13)C isotopic signatures confirmed feathers as the main food resource for the three lice species and blood for the flea species. All ectoparasite species showed a significant enrichment in delta(15)N relatively to the host tissue consumed (discrimination factors ranged from 2 to 5 per thousand depending on the species). Isotopic differences were consistent across multiple host-ectoparasite locations, despite of some geographic variability in baseline isotopic levels. Our findings illustrate the influence of both ectoparasite and host trophic ecology in the isotopic structuring of the Calonectris ectoparasite community. This study highlights the potential of stable isotope analyses in disentangling the nature and complexity of trophic relationships in symbiotic systems.
authors.affiliation: Institut de Recerca de la Biodiversitat i Departament Biologia Animal (Vertebrats), Universitat de Barcelona, Barcelona, Spain. elegomez@ub.edu
authors.forename: Elena
authors.initials: E
authors.lastname: Gómez-Díaz
authors.forename: Jacob
authors.initials: J
authors.lastname: González-Solís
mesh_terms: D000818:Animals; D001717:Birds / Q000469:parasitology*; D002247:Carbon Isotopes; D020387:Food Chain; D005843:Geography; D006790:Host-Parasite Interactions; D007553:Isotope Labeling / Q000379:methods*; D009587:Nitrogen Isotopes; D010271:Parasites / Q000502:physiology
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes
references.citation: Dis Aquat Organ. 2002 Nov 7;52(1):77-86
references.pmid: 12517008
references.citation: Physiol Biochem Zool. 2005 Jan-Feb;78(1):106-15
references.pmid: 15702469
references.citation: Oecologia. 1999 Aug;120(3):314-326
references.pmid: 28308009
references.citation: Trends Ecol Evol. 2008 Nov;23(11):610-8
references.pmid: 18823679
references.citation: Oecologia. 2010 Jun;163(2):303-11
references.pmid: 20043177
references.citation: Trends Ecol Evol. 2000 Sep;15(9):358-364
references.pmid: 10931667
references.citation: Biol Lett. 2009 Aug 23;5(4):545-8
references.pmid: 19364709
references.citation: Parasitology. 2005 Aug;131(Pt 2):279-85
references.pmid: 16145945
references.citation: Ecol Lett. 2008 Jun;11(6):533-46
references.pmid: 18462196
references.citation: Isotopes Environ Health Stud. 1998;34(1-2):81-5
references.pmid: 9854844
references.citation: Trends Ecol Evol. 2007 Mar;22(3):133-9
references.pmid: 17137676
references.citation: Parasitology. 1995 Feb;110 ( Pt 2):195-206
references.pmid: 7885738
references.citation: Ecol Appl. 2007 Jul;17(5):1484-98
references.pmid: 17708223
references.citation: Trends Ecol Evol. 2009 Mar;24(3):127-35
references.pmid: 19185386
references.citation: Trends Parasitol. 2008 Jan;24(1):24-8
references.pmid: 18023259
references.citation: Mol Phylogenet Evol. 2006 Nov;41(2):322-32
references.pmid: 16814569
references.citation: Annu Rev Entomol. 2003;48:185-209
references.pmid: 12208818
references.citation: Oecologia. 2006 Dec;150(3):355-61
references.pmid: 17013599