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Article: What does stable isotope analysis reveal about trophic relationships and the relative importance of allochthonous and autochthonous resources in tropical streams? A synthetic study from Hong Kong

TitleWhat does stable isotope analysis reveal about trophic relationships and the relative importance of allochthonous and autochthonous resources in tropical streams? A synthetic study from Hong Kong
Authors
KeywordsEnergy flow
Food web
Riparian shading
Seasonal effect
Trophic position
Issue Date2009
PublisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/FWB
Citation
Freshwater Biology, 2009, v. 54 n. 1, p. 127-141 How to Cite?
Abstract1. Analysis of the stable isotope signatures of carbon (C) and nitrogen (N) of foods and consumers has led to some preliminary understanding of the relative importance of autochthonous and allochthonous resources in tropical streams. However, robust generalizations about the dynamics of food webs in these habitats, and their response to shading gradients or season, are still lacking. In addition, the feasibility of employing a baseline δ15N value for estimating trophic positions (TPs) of consumers in small tropical streams has yet to be explored. 2. We analysed data on stable isotope signatures of food sources and aquatic consumers obtained from 14 studies carried out in small streams in monsoonal Hong Kong (22°30′N, 114°10′E) between 1996 and 2006. Emphasis was placed on determining the relative importance of leaf litter and autochthonous foods in supporting consumer biomass, and the extent to which trophic base and TP vary among streams and seasons. 3. Although allochthonous leaf litter was generally 13C- and 15N-depleted relative to autochthonous foods, there were marked isotopic shifts of food sources and consumers in response to season (dry versus wet) and stream shading. Consumer taxa were generally more 13C- and 15N-enriched in the unshaded streams, but seasonal effects were more variable. Despite these changes, there was consistent evidence that stream food webs were based on periphytic algae and/or cyanobacteria with leaf litter serving as a minor food. 4. Heptageniidae (Ephemeroptera), Tipulidae (Diptera), Elmidae (Coleoptera) and shrimps (Atyidae) were used as a baseline for calculating the TPs of other consumer taxa. The maximum TPs in shaded streams remained fairly constant between seasons (dry = 3.93; wet = 3.97), while those in unshaded streams were higher and showed seasonal fluctuations (dry = 5.13; wet = 4.39). 5. Although variations in consumer isotope signatures in response to season and shading gradients did not confound our interpretation of the stream food base, changes in consumer δ15N did affect the calculation of consumer TPs. Misleading estimates of consumer TPs are likely if samples are collected from a narrow range of streams and/or during one season. Overestimation of the TPs of specialist herbivores (e.g. fish grazers) is also possible when autochthonous resources are substantially more 15N-enriched than allochthonous foods. © 2008 The Authors.
Persistent Identifierhttp://hdl.handle.net/10722/60667
ISSN
2015 Impact Factor: 2.933
2015 SCImago Journal Rankings: 1.574
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLau, DCPen_HK
dc.contributor.authorLeung, KMYen_HK
dc.contributor.authorDudgeon, Den_HK
dc.date.accessioned2010-05-31T04:16:09Z-
dc.date.available2010-05-31T04:16:09Z-
dc.date.issued2009en_HK
dc.identifier.citationFreshwater Biology, 2009, v. 54 n. 1, p. 127-141en_HK
dc.identifier.issn0046-5070en_HK
dc.identifier.urihttp://hdl.handle.net/10722/60667-
dc.description.abstract1. Analysis of the stable isotope signatures of carbon (C) and nitrogen (N) of foods and consumers has led to some preliminary understanding of the relative importance of autochthonous and allochthonous resources in tropical streams. However, robust generalizations about the dynamics of food webs in these habitats, and their response to shading gradients or season, are still lacking. In addition, the feasibility of employing a baseline δ15N value for estimating trophic positions (TPs) of consumers in small tropical streams has yet to be explored. 2. We analysed data on stable isotope signatures of food sources and aquatic consumers obtained from 14 studies carried out in small streams in monsoonal Hong Kong (22°30′N, 114°10′E) between 1996 and 2006. Emphasis was placed on determining the relative importance of leaf litter and autochthonous foods in supporting consumer biomass, and the extent to which trophic base and TP vary among streams and seasons. 3. Although allochthonous leaf litter was generally 13C- and 15N-depleted relative to autochthonous foods, there were marked isotopic shifts of food sources and consumers in response to season (dry versus wet) and stream shading. Consumer taxa were generally more 13C- and 15N-enriched in the unshaded streams, but seasonal effects were more variable. Despite these changes, there was consistent evidence that stream food webs were based on periphytic algae and/or cyanobacteria with leaf litter serving as a minor food. 4. Heptageniidae (Ephemeroptera), Tipulidae (Diptera), Elmidae (Coleoptera) and shrimps (Atyidae) were used as a baseline for calculating the TPs of other consumer taxa. The maximum TPs in shaded streams remained fairly constant between seasons (dry = 3.93; wet = 3.97), while those in unshaded streams were higher and showed seasonal fluctuations (dry = 5.13; wet = 4.39). 5. Although variations in consumer isotope signatures in response to season and shading gradients did not confound our interpretation of the stream food base, changes in consumer δ15N did affect the calculation of consumer TPs. Misleading estimates of consumer TPs are likely if samples are collected from a narrow range of streams and/or during one season. Overestimation of the TPs of specialist herbivores (e.g. fish grazers) is also possible when autochthonous resources are substantially more 15N-enriched than allochthonous foods. © 2008 The Authors.en_HK
dc.languageengen_HK
dc.publisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/FWBen_HK
dc.relation.ispartofFreshwater Biologyen_HK
dc.rightsFreshwater Biology. Copyright © Blackwell Publishing Ltd.en_HK
dc.subjectEnergy flowen_HK
dc.subjectFood weben_HK
dc.subjectRiparian shadingen_HK
dc.subjectSeasonal effecten_HK
dc.subjectTrophic positionen_HK
dc.titleWhat does stable isotope analysis reveal about trophic relationships and the relative importance of allochthonous and autochthonous resources in tropical streams? A synthetic study from Hong Kongen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0046-5070&volume=54&spage=127&epage=141&date=2009&atitle=What+does+stable+isotope+analysis+reveal+about+trophic+relationships+and+the+relative+importance+of+allochthonous+and+autochthonous+resources+in+tropical+streams?+A+synthetic+study+from+Hong+Kong+en_HK
dc.identifier.emailLeung, KMY: kmyleung@hku.hken_HK
dc.identifier.emailDudgeon, D: ddudgeon@hku.hken_HK
dc.identifier.authorityLeung, KMY=rp00733en_HK
dc.identifier.authorityDudgeon, D=rp00691en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1111/j.1365-2427.2008.02099.xen_HK
dc.identifier.scopuseid_2-s2.0-57449112538en_HK
dc.identifier.hkuros154260en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-57449112538&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume54en_HK
dc.identifier.issue1en_HK
dc.identifier.spage127en_HK
dc.identifier.epage141en_HK
dc.identifier.isiWOS:000261621400011-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridLau, DCP=23089080800en_HK
dc.identifier.scopusauthoridLeung, KMY=7401860738en_HK
dc.identifier.scopusauthoridDudgeon, D=7006559840en_HK
dc.identifier.citeulike3780154-

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