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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Lentic Ecology
HEXAGENIA SPP. (EPHEMEROPTERA: EPHEMERIDAE) BIOTURBATION: EFFECTS OF SIZE, DENSITY AND TEMPERATURE ON SEDIMENT FLUX.
A.M. Bachteram and J.J.H. Ciborowski. Department of Biological Sciences and Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, CANADA N9B 3P4
Suspended sediment in lakes can influence primary production, water clarity and invertebrate filtering efficiency. Hexagenia mayflies, which have recently recolonized western Lake Erie, may cause significant sediment suspension (bioturbation) through burrow construction, burrow irrigation and feeding activity. We inoculated 2–L jars containing Lake Erie sediment with larvae of specific densities (70 – 1,111 larvae m-2) and sizes (10 – 25 mm length) in a 5x5 factorial design to determine sediment flux caused by Hexagenia bioturbation. Total suspended solids (TSS [mg L-1]) were estimated from water samples, collected every 12 h, using spectrophotometer readings (absorbance at 750 nm). The amount and rate of bioturbation were a function of larval density, larval size and temperature. At 20° C, sediment flux by small larvae engaged in burrow maintenance and feeding, ranged from 0.24±0.11 g m-2 d-1 (70 10 – mm long larvae m-2) to 2.86±0.87 g m-2 d-1 (556 larvae m-2). Large larvae (556 larvae m-2; >25 mm long) suspended 134.3±24.8 g m-2d-1. Initial burrow construction produced 30-50% more flux than this. Hexagenia bioturbation generates much more suspended sediment than chironomids or oligochaetes at natural densities.
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