Variability of benthic methane‐derived carbon along seasonal, biological, and sedimentary gradients in a polymictic lake. (31st August 2020)

• Record Type: Journal Article
• Authors: Tsuchiya, Kenji; Komatsu, Kazuhiro; Shinohara, Ryuichiro; Imai, Akio; Matsuzaki, Shin‐ichiro S.; Ueno, Ryuhei; Kuwahara, Victor S.; Kohzu, Ayato
• Is Part Of: Limnology and oceanography. Volume 65:Number 12(2020)
• Page Start: 3017
• Page End: 3031
• Publication Date: 2020-08-31
• Subjects: Limnology -- Periodicals; Oceanography -- Periodicals; Océanographie; Limnologie; Limnology; Oceanography; Computer network resources; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); Periodicals; 551.4805
• DOI: 10.1002/lno.11571
• Languages: English
• ISSNs: 0024-3590

Abstract

Abstract: The spatial and seasonal variations of methane‐derived carbon contributions to Chironomus plumosus larvae and oligochaetes biomass at four stations in a polymictic, eutrophic lake were examined to determine which factors (CH4 and/or dissolved oxygen) affect the methane‐derived carbon contributions, and quantify impacts of benthic methane‐derived carbon on the lake food web. Methane‐derived carbon contributions were estimated by a two‐source mixing model using δ 13 C values of monthly particulate organic matter ( −29.5 to −20.8‰) and methane‐oxidizing bacteria (−85.7‰). Large spatial and seasonal variability of methane‐derived carbon contributions to C. plumosus and oligochaetes within the lake (0–38% and 0–32%, respectively) were observed, where contributions varied spatially along a gradient of sediment CH4 concentration, but not dissolved oxygen. The results suggest that for both C. plumosus and oligochaetes, spatial variabilities of the methane‐derived carbon contributions are regulated by CH4 . Seasonal variability of methane‐derived carbon contributions to C. plumosus revealed increases in summer and autumn following increases in CH4 . Methane‐derived biomass (methane‐derived carbon% × biomass) of C. plumosus were also higher in summer and autumn, suggesting transfer of methane‐derived carbon to higher trophic organisms may be larger during those seasons, and limited in winter and spring. Although oligochaetes did not show seasonal variability of methane‐derived carbon contributions, they provided a consistent source of methane‐derived biomass to higher trophic levels throughout the year. Our study demonstrates that two major macroinvertebrates complementarily contribute to fueling methane‐derived carbon cycling through trophic transfer in a polymictic lake.