The purpose of this study was to analyze the
production of the benthic macroinvertebrates in a
commercially navigated river in order to assess the
environmental impacts of increasing levels of traffic.
Production was estimated for 16 taxa at two sites in the
Winfield navigational pool (Upper Winfield - UW; Lower
Winfield - LW). Total production of all taxa on
cobble/pebble substrates was 43,838 mgDW/m2/yr at UW and
16,553 mgDW/m2/yr at LW. Production on sand/silt substrates
was lower, 3,534 mgDW/m2/yr at UW and 2,405 mgDW/m2/yr at
LW. On cobble/pebble substrates the production was mostly
accounted for by Diptera (76.0% UW, 85.2% LW), Trichoptera
(12.4% UW, 5.8% LW), and Ephemeroptera (10.8% UW, 5.8% LW).
On sand/silt substrates virtually all production was
accounted for by Diptera. Total macroinvertebrate
production for an "average" square meter of the Winfield
Pool was estimated as 6,228 mgDW/m 2/yr.