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δ 13 C composition of primary producers and role of detritus in a freshwater coastal ecosystem
Author(s) -
Keough Janet R.,
Hagley Cynthia A.,
Ruzycki Elaine,
Sierszen Michael
Publication year - 1998
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1998.43.4.0734
Subject(s) - primary producers , detritus , phytoplankton , macrophyte , autotroph , food web , environmental science , wetland , dissolved organic carbon , environmental chemistry , ecosystem , algae , oceanography , carbon fibers , trophic level , isotopes of carbon , ecology , chemistry , total organic carbon , nutrient , biology , geology , genetics , materials science , bacteria , composite number , composite material
Stable‐isotope ratio signatures of primary producers in a coastal wetland and in adjacent offshore waters of western Lake Superior indicated that phytoplankton are the primary source of carbon for the grazing food web of this ecosystem. This study outlines the possible roles of other autotrophs in this regard. Isotopic signatures of macrophytes reflected their life‐form‐associated constraints on diffusion of inorganic carbon. Data indicated that differences between wetland and lake phytoplankton may be explained by the isotopic signatures of their dissolved inorganic carbon (DIC) sources. Results of an in situ experiment showed that respiration associated with macrophyte decomposition is capable of enriching surrounding water with significant amounts of 13 C‐depleted DIC and lowering the net δ 13 C ratio of DIC in water in lowturbulence situations. The δ 13 C ratio for wetland phytoplankton may be depleted relative to pelagic algae because the fixed carbon is derived from decomposing detritus.