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Carbon storage reservoirs in watersheds support stream food webs via periphyton production
Author(s) -
Ishikawa Naoto F.,
Uchida Masao,
Shibata Yasuyuki,
Tayasu Ichiro
Publication year - 2014
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/13-0976.1
Subject(s) - periphyton , environmental science , ecology , production (economics) , carbon fibers , food web , biomass (ecology) , hydrology (agriculture) , ecosystem , biology , geology , computer science , geotechnical engineering , macroeconomics , algorithm , composite number , economics
We measured the natural abundances of radiocarbon (Δ 14 C) in macroinvertebrates, fishes, and their potential food sources, collected from the upper and lower reaches of six temperate streams in Lake Biwa basin (central Japan), three of which flow on limestone bedrock. Several carbon storage reservoirs in the watersheds show distinctive Δ 14 C signatures (e.g., ancient carbonate rocks, −1000‰; modern atmospheric CO 2 , +50‰). Our analyses showed that the Δ 14 C values for periphytic algae range from −361‰ to +21‰, reflecting 14 C‐depleted signals from watershed storage reservoirs (carbonate rocks and/or soils). In contrast, the Δ 14 C values for coarse particulate organic matter (CPOM) range from −6‰ to +62‰, reflecting 14 C‐enriched signals from modern atmospheric CO 2 . The periphyton from streams on limestone bedrock was more 14 C‐depleted than that from streams in non‐limestone areas, although the Δ 14 C values for periphyton from the latter were less than modern atmospheric 14 CO 2 concentration. The Δ 14 C values for most of the consumers were between those for periphyton and CPOM. Based on a Δ 14 C two‐source mixing models, the results suggested that the grazers rely on periphyton, while the carbon source for collectors and predators shifts from CPOM in the upper reaches of streams to periphyton in the lower reaches. The Δ 14 C signature can trace carbon from watershed storage reservoirs to benthic production, which suggests that stream food webs are composed of mixtures of carbon originating from various sources of different ages.