| Summary: | During the summer 2006, I tested the importance of dissolved and particulate basal carbon sources to the caddisfly, Grensia praeterita, and the fingernail clam, Sphaerium nitidium, using intact sediment cores in a 1-month incubation experiment. Carbon sources included a 13C labeled seston treatment, an algal-derived DO13C treatment, a 13C- methyl labeled acetate treatment, and a 13C- carboxyl labeled acetate treatment. Grensia and Sphaerium were both found to rely on both particulate and dissolved carbon sources. While enrichment from the 13C labeled seston treatment (particulate source) was the largest source for both organisms, Grensia and Sphaerium both showed reliance on microbial loop processing as seen by assimilation of the algal-derived DO13C treatment. Sphaerium also assimilated carbon derived from methanogenic and non-methanogenic pathways of the microbial loop, based on differential assimilation of the two 13C labeled acetate treatments.
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