The fate of marine-derived nutrients: tracing delta super(13)C and delta super(15)N through oligotrophic freshwater and linked riparian ecosystems following salmon carcass analog additions

The oligotrophic condition of salmon-bearing catchments in the Columbia River Basin is a potential limiting factor for the recovery of Pacific salmon (Oncorhynchus spp.). To address this issue, nutrient supplementation programs attempt to mitigate for reduced marine-derived nutrients (MDN). We exami...

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Bibliographic Details
Published in:Canadian journal of fisheries and aquatic sciences 2017-01, Vol.74 (1), p.41-55
Main Authors: Richardson, David P, Kohler, Andre E, Hailemichael, Million, Finney, Bruce P
Format: Article
Language:English
Subjects:
Entosphenus tridentatus
Freshwater
Marine
Oncorhynchus
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Summary:The oligotrophic condition of salmon-bearing catchments in the Columbia River Basin is a potential limiting factor for the recovery of Pacific salmon (Oncorhynchus spp.). To address this issue, nutrient supplementation programs attempt to mitigate for reduced marine-derived nutrients (MDN). We examined the assimilation of MDN in the biota of tributaries of the Salmon River Basin, Idaho, USA, following the addition of salmon carcass analogs (SCA). We measured carbon (C) and nitrogen (N) stable isotopes from biofilm, macroinvertebrate, salmonid fish, and riparian vegetation samples and found significant super(15)N enrichment and substantial assimilation of SCA material in all aquatic trophic levels and in riparian vegetation. Our results suggest that SCA are incorporated primarily through indirect pathways and provide a source of MDN to multiple trophic levels in freshwater and linked riparian ecosystems.Original Abstract: Le caractere oligotrophe des bassins versants contenant des saumons dans le bassin du fleuve Columbia pourrait etre un facteur qui limite le retablissement des saumons du Pacifique (Oncorhynchus spp.). Pour contrer ce probleme, des programmes de supplementation en nutriments ont ete mis sur pied pour tenter d'attenuer la baisse des nutriments d'origine marine (NOM). Nous avons examine l'assimilation de NOM dans les biotes d'affluents du bassin de la riviere Salmon (Idaho, Etats-Unis) apres l'ajout d'analogues de carcasse de saumon (ACS). Nous avons mesure les isotopes stables du carbone (C) et de l'azote (N) d'echantillons de biofilms, de macroinvertebres, de salmonides et de vegetation riveraine et constate un enrichissement significatif en super(15)N et une importante assimilation de matieres provenant d'ACS dans tous les niveaux trophiques aquatiques et dans la vegetation riveraine. Nos resultats donnent a penser que les ACS sont incorpores principalement par des voies indirectes et constituent une source de NOM pour plusieurs niveaux trophiques dans les ecosystemes d'eau douce et les ecosystemes riverains auxquels ces derniers sont relies. [Traduit par la Redaction]
ISSN:0706-652X
1205-7533
DOI:10.1139/cjfas-2015-0500