Different carbon support for respiration and secondary production in unproductive lakes

• Published in: Oikos
• Main Author: Karlsson, Jan
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2007
• Subjects: Northern Sweden
• Online Access: http://dx.doi.org/10.1111/j.0030-1299.2007.15825.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.0030-1299.2007.15825.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0030-1299.2007.15825.x; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/j.0030-1299.2007.15825.x

This study investigates the allocation of allochthonous organic carbon (AlloOC) to pelagic respiration and biomass production in unproductive lakes. Metabolic process rates and stable isotopic composition (δ 13 C) of crustacean zooplankton and respired CO 2 were measured in the epilimnion of 13 forest lakes in northern Sweden. The δ 13 C of zooplankton was low (−31.2 to −38.0‰) compared to that of respired CO 2 (−28.4 to −30.6‰), implying that the relative importance of AlloOC was lower for zooplankton (ca 40%) than for respiration (ca 80%). Combining δ 13 C and carbon flux data revealed that a large amount of metabolized AlloOC was lost in respiration, compared to the amount transferred to zooplankton (<3%). Thus, despite large respiratory losses, AlloOC was still important for zooplankton growth, implying a high supply of AlloOC in comparison to phytoplankton generated organic carbon in the lakes.