Young, Old, and Weathered Carbon—Part 2: Using Radiocarbon and Stable Isotopes to Identify Terrestrial Carbon Support of the Food Web in an Alkaline, Humic Lake

Abstract

Carbon (C) and nitrogen (N) stable isotope analysis (SIA) has been used to identify the terrestrial subsidy of freshwater food webs. However, SIA fails to differentiate between the contributions of old and recently fixed terrestrial C and consequently cannot fully determine the source, age and biochemical quality of terrestrial carbon. Natural abundance radiocarbon

Radioisotope and stable isotope ratios (Δ14C, δ15N) suggest larval lamprey growth is dependent on both fresh and aged organic matter in streams

“…This study is one of the few studies that have used natural 14 C to assess nutritional resource utilisation by fish Ishikawa et al, 2014;Keaveney, Reimer, & Foy, 2015). There is increasing recognition that aged forms of OM can support consumer production in aquatic ecosystems Guillemette et al, 2017).…”

“…There is increasing recognition that aged forms of OM can support consumer production in aquatic ecosystems Guillemette et al, 2017). For instance, Keaveney et al (2015) found evidence for utilisation of aged allochthonous nutritional sources by Daphnia spp. in a humic lake; however, algal sources and other fresh allochthonous OM contributed to fishes and other zooplankton in this same study.…”

“…For instance, Keaveney et al (2015) found evidence for utilisation of aged allochthonous nutritional sources by Daphnia spp. Keaveney et al (2015) were able to establish these differences in consumer nutritional resources by using both δ 13 C and δ 15 N in conjunction with natural 14 C. The use of natural 14 C in food web studies has facilitated our understanding of the role aged materials in aquatic food webs and challenged traditional paradigms that modern sources of primary production are the exclusive or even dominant source of aquatic consumer nutrition. Keaveney et al (2015) were able to establish these differences in consumer nutritional resources by using both δ 13 C and δ 15 N in conjunction with natural 14 C. The use of natural 14 C in food web studies has facilitated our understanding of the role aged materials in aquatic food webs and challenged traditional paradigms that modern sources of primary production are the exclusive or even dominant source of aquatic consumer nutrition.…”

Radiocarbon in ecology: Insights and perspectives from aquatic and terrestrial studies

“…To demonstrate the potential of combining both stable and radio isotopes, we applied the Bayesian mixing model “Food Reconstruction Using Isotopic Transferred Signals” (FRUITS) (Fernandes, Millard, Brabec, Nadeau, & Grootes, ) using isotopic values of pollans ( Coregonus pollan ), its food sources, and diet‐to‐consumer isotopic offsets according to Keaveney et al. (). As relevant food sources, we included calanoid zooplankton, chironomidae, Daphnia , and littoral invertebrates (Wilson, ).…”

Nutritional support of inland aquatic food webs by aged carbon and organic matter

“…Extensive work in Lough Erne, Ireland has similarly shown algae to be 14 C‐depleted (mean Δ 14 C = −59 ± 9‰; 490 yr equivalent age), suggesting a significant freshwater reservoir offset, presumably from inputs of weathered fossil carbonates and/or aged soil CO 2 to lake DIC (Keaveney et al 2015 a,b ). In contrast, some consumers in Lough Erne were enriched in 14 C (maximum invertebrate and fish Δ 14 C values were 0‰ and 10‰, respectively, and modern‐aged; Fig.…”