02912nas a2200145   4500008004100000245009700041210006900138260001600207300000800223490000600231520242800237100002402665700002502689856005202714       2010                        eng d00aTrophic Structure in a Seabird Host-Parasite Food Web: Insights from Stable Isotope Analyses0 aTrophic Structure in a Seabird HostParasite Food Web Insights fr  cApr-05-2010  a7pp0 v53 a<p>Ecological&nbsp; studies&nbsp; on&nbsp; food&nbsp; webs&nbsp; rarely&nbsp; include&nbsp; parasites,&nbsp; partly&nbsp; due&nbsp; to&nbsp; the&nbsp; complexity&nbsp; and&nbsp; dimensionality&nbsp; of&nbsp; host-parasiteinteraction&nbsp; networks.&nbsp; Multiple&nbsp; co-occurring&nbsp; parasites&nbsp; can&nbsp; show&nbsp; different&nbsp; feeding&nbsp; strategies&nbsp; and&nbsp; thus&nbsp; lead&nbsp; to&nbsp; complex&nbsp; andcryptic&nbsp; trophic&nbsp; relationships,&nbsp; which&nbsp; are&nbsp; often&nbsp; difficult&nbsp; to&nbsp; disentangle&nbsp; by&nbsp; traditional&nbsp; methods.&nbsp; We&nbsp; analyzed&nbsp; stable&nbsp; isotoperatios&nbsp; of&nbsp; C&nbsp; (13C/12C,d13C)&nbsp; and&nbsp; N&nbsp; (15N/14N,d15N)&nbsp; of&nbsp; host&nbsp; and&nbsp; ectoparasite&nbsp; tissues&nbsp; to&nbsp; investigate&nbsp; trophic&nbsp; structure&nbsp; in&nbsp; 4&nbsp; co-occurring&nbsp; ectoparasites:&nbsp; three&nbsp; lice&nbsp; and&nbsp; one&nbsp; flea&nbsp; species,&nbsp; on&nbsp; two&nbsp; closely&nbsp; related&nbsp; and&nbsp; spatially&nbsp; segregated&nbsp; seabird&nbsp; hosts(Calonectrisshearwaters).d13C&nbsp; isotopic&nbsp; signatures&nbsp; confirmed&nbsp; feathers&nbsp; as&nbsp; the&nbsp; main&nbsp; food&nbsp; resource&nbsp; for&nbsp; the&nbsp; three&nbsp; lice&nbsp; speciesand blood for the flea species. All ectoparasite species showed a significant enrichment ind15N relatively to the host tissueconsumed&nbsp; (discrimination&nbsp; factors&nbsp; ranged&nbsp; from&nbsp; 2&nbsp; to&nbsp; 5%depending&nbsp; on&nbsp; the&nbsp; species).&nbsp; Isotopic&nbsp; differences&nbsp; were&nbsp; consistentacross&nbsp; multiple&nbsp; host-ectoparasite&nbsp; locations,&nbsp; despite&nbsp; of&nbsp; some&nbsp; geographic&nbsp; variability&nbsp; in&nbsp; baseline&nbsp; isotopic&nbsp; levels. Our&nbsp; findingsillustrate&nbsp;&nbsp; the&nbsp;&nbsp; influence&nbsp;&nbsp; of&nbsp;&nbsp; both&nbsp;&nbsp; ectoparasite&nbsp;&nbsp; and&nbsp;&nbsp; host&nbsp;&nbsp; trophic&nbsp;&nbsp; ecology&nbsp;&nbsp; in&nbsp;&nbsp; the&nbsp;&nbsp; isotopic&nbsp;&nbsp; structuring&nbsp;&nbsp; of&nbsp;&nbsp; theCalonectrisectoparasite&nbsp; community.&nbsp; This&nbsp; study&nbsp; highlights&nbsp; the&nbsp; potential&nbsp; of&nbsp; stable&nbsp; isotope&nbsp; analyses&nbsp; in&nbsp; disentangling&nbsp; the&nbsp; nature&nbsp; andcomplexity&nbsp; of&nbsp; trophic&nbsp; relationships&nbsp; in&nbsp; symbiotic&nbsp; systems.</p>
1 aGómez-Díaz, Elena1 aGonzález-Solís, J.  uhttp://dx.plos.org/10.1371/journal.pone.0010454