Monday, June 4, 2007 - 1:15 PM
16

Production and life cycle of Hexagenia bilineata (Say) (Ephemeroptera: Ephemeridae) in Kentucky Lake, southwestern Kentucky

James B. Ramsey1, David S. White1, and Hwa-Seong Jin2. (1) Biological Sciences, Murray State University, Hancock Biological Station, 561 Emma Dr, Murray, KY 42071, (2) Biology, University of Louisville, Department of Biology, Louisville, KY 40292

We studied the life cycle and secondary production of Hexagenia bilineata (Say) in Ledbetter Embayment of Kentucky Lake (KL) to determine its role in the ecology of the embayment and make comparisons between KL and other systems.  We sampled for 12 Months (Oct-2005 thru Oct-2006 excluding Feb-2006) using a geographically referenced, random design for the entire embayment and a transect-station method to sample a densely populated region of the embayment.  The majority of the population was semivoltine although a portion was univoltine.  Annual production for the embayment was estimated as 184.83 mg m-2 AFDM and 274.27 mg m-2 AFDM for the densely populated transect.  Mean densities were 21 m-2 and 56 m-2 for the embayment and dense transect, respectively.  Estimates of Hexagenia production provide useful comparisons among ecosystems and regions of North America.  Production by Hexagenia in KL was low compared with other reservoirs and lakes, possibly due to interspecific interference or year-to-year fluctuation in production resulting from cohort leakage.  It appears that Hexagenia may contribute less to benthic trophic flow in KL than in other reservoirs and lakes where it occurs.  Large chironomids likely constitute a greater proportion of benthic macroinvertebrate production in KL.

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