Food web structure and the role of epilithic biofilms in cave streams

dc.contributorVirginia Techen
dc.contributor.authorSimon, K. S.en
dc.contributor.authorBenfield, Ernest F.en
dc.contributor.authorMacko, S. A.en
dc.contributor.departmentBiological Sciencesen
dc.date.accessed2014-03-11en
dc.date.accessioned2014-03-27T13:06:03Zen
dc.date.available2014-03-27T13:06:03Zen
dc.date.issued2003-09en
dc.description.abstractCave stream food webs rely exclusively on detritus from the surface for energy and represent a heterotrophic end point in the continuum of stream types. Both dissolved organic matter (DOM) and particulate organic matter, and associated microbes, are available in caves, but the relative importance of these foods is unclear. We examined trophic structure and the roles of particulate organic matter and DOM retained in epilithic biofilms in three cave streams using natural abundance isotopes (C-13 and N-15) and C-13 tracer additions. Natural abundance N-15 ratios showed that cave animals occupied two trophic levels: primary consumers and predators. Epilithic biofilms and animals were highly enriched in N-15, suggesting that dissolved organic matter from surface soils was incorporated into epilithon and supported stream food webs, even when coarse particulate organic matter (CPOM) from the surface was abundant. We conducted 28-day C-13-acetate tracer additions to trace the use of epilithon carbon in the food webs. The tracer(13)C acetate was rapidly taken up in the streams at uptake velocities (0.5-22.8 x 10(-5) m/s) and uptake rates (0.04-0.23 mg m(-2) h(-1)) similar to those in surface streams. Epilithon was highly labeled and epilithon turnover time was relatively long (10.0-16.7 d), showing that C from DOM was immobilized in biofilms and thus available to invertebrates, which also became labeled with tracer by the end of the experiment. Several snails (Fontigens tartarea, Gyraulus parvus, and Physa sp.) that fed directly on epilithon were highly enriched with tracer C-13. Other primary consumers (Gammarus minus and Caecidotea holsingeri) fed on a combination of epilithon and fine particulate organic matter. Predators in the streams (Stygobromus emarginatus, S. spinatus, and Macrocotyla hoffmasteri) also became labeled with C-13, indicating that biofilm C was passed through the entire food web. This study shows that DOC and epilithic biofilms are important energy sources for stream communities even when CPOM is an abundant resource.en
dc.description.sponsorshipNSF Grant (DEB-9801082)en
dc.description.sponsorshipSigma Xien
dc.description.sponsorshipNational Speleological Societyen
dc.description.sponsorshipVirginia Tech Graduate Student Associationen
dc.description.sponsorshipBiology Department at Virginia Techen
dc.identifier.citationK. S. Simon, E. F. Benfield, and S. A. Macko 2003. FOOD WEB STRUCTURE AND THE ROLE OF EPILITHIC BIOFILMS IN CAVE STREAMS. Ecology 84:2395-2406. http://dx.doi.org/10.1890/02-334en
dc.identifier.doihttps://doi.org/10.1890/02-334en
dc.identifier.issn0012-9658en
dc.identifier.urihttp://hdl.handle.net/10919/46831en
dc.identifier.urlhttp://www.esajournals.org/doi/pdf/10.1890/02-334en
dc.language.isoen_USen
dc.publisherEcological Society of Americaen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectc-13en
dc.subjectcaveen
dc.subjectepilithic biofilmsen
dc.subjectfood websen
dc.subjectmicrobial loopen
dc.subjectn-15en
dc.subjectstableen
dc.subjectisotopeen
dc.subjectstreamen
dc.subjectdissolved organic-carbonen
dc.subjecttrophic significanceen
dc.subjectstable isotopesen
dc.subjecttundraen
dc.subjectriveren
dc.subjectecosystemen
dc.subjectmatteren
dc.subjectimmobilizationen
dc.subjectmechanismsen
dc.subjectbreakdownen
dc.subjectdynamicsen
dc.titleFood web structure and the role of epilithic biofilms in cave streamsen
dc.title.serialEcologyen
dc.typeArticle - Refereeden

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