Abstract

Partitioning of C-14 from labeled diatoms (Strephanodiscus hantzschii Grun v. pusillus) within a freshwater benthic community was determined in a microcosm study for three different treatments: sediment with only natural, ambient meio- and microfauna, and microbes, addition of 30 Chydorus sphaericus Muller per microcosm, and addition of four Chironomus riparius Meigen larvae per microcosm. Assimilation of C-14 label in Chironomus, Chydorus, ambient meiofauna, respired C-14, and [C-14]DOC in both overlying and interstitial waters was measured, and [C-14]POC was calculated. The carbon budget clearly sowed a rapid assimilation of diatom C by surface deposit-feeding Chironomus larvae, more than 20% of the total added label was used after 8 d. Community respiration in the Chironomus treatment increased from 6% on day 2 to 18% on day 8, or 92% higher than that of the treatments with ambient meiofauna only and added Chydorus. Chironomus respiration was low relative to assimilation, indicating that larvae efficiently used the easily accessible and digestible food resource. Sediment microheterotrophs (microbes and microfauna) were also found to be important quantitatively for C turnover. Respiration by microheterotrophs was similar to 10% of the total added label after 8 d.

Published in

Limnology and Oceanography
1997, Volume: 42, number: 3, pages: 452-460

SLU Authors

• Johnson, Richard

  • Department of Environmental Assessment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.4319/lo.1997.42.3.0452

Permanent link to this page (URI)

https://res.slu.se/id/publ/88286