Tuesday, May 27, 2008 - 11:00 AM
169

Benthic secondary production in eight oligotrophic arctic lakes

Robert Northington, University of North Carolina - Greensboro, Greensboro, NC 27403, Anne E. Hershey, Biology, UNC - Greensboro, 312 Eberhart, Greenboro, NC 27402, Steve C. Whalen, Environmental Sciences and Engineering, UNC, Chapel Hill, NC 27599, Matt D. Keyse, University of Alaska, Fairbanks, AK 99775, and S.R. Beaty, Division of Water Quality, North Carolina Department of Environment and Natural Resources,, 512 N. Salisbury St, Raleigh, NC 27604.

Across aquatic ecosystems, benthic secondary production is generally believed to be controlled by autochthonous primary production. We estimated secondary production in eight oligotrophic arctic lakes of varying morphometric characteristics and glacial till age, and for which we also had estimates of pelagic and benthic primary production, during the summer of 2001. The size frequency method was used to calculate CPI-corrected lake productivity and P/B ratios for all taxa in all lakes. Taxa examined from sediment samples included Baetis spp., Grensia praeterita, Lymnaea elodes, Valvata spp., Sphaeriid clams and larval chironomids.  Larval chironomids had the greatest productivity overall, with highest production for Chironomini, especially Chironomus spp., in 7 of the 8 lakes.  The exception was lake GTH 99, where Tanytarsini were the most productive taxon. GTH 99 was also the most productive lake with 13 mg C m-2 yr-1 overall. No significant relationships were found between secondary production and any lake morphometric variables. Additionally, no relationship was found between benthic secondary production and primary production (benthic or pelagic). This study is unique in that not only were multiple lakes examined, but we demonstrated that the secondary production of benthic fauna is not closely tied to autochthonous primary production in these lakes, in contrast to the commonly accepted paradigm.


Web Page: secondary production, arctic lakes, oligotrophic

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