Drifting Fine Particulate Organic Matte below Glen Canyon Dam in the Colorado River, Arizona

Abstract

The concentration and composition of drifting fine particulate organic matter (FPOM) in regulated rivers may be influenced by dam operations and site of collection within the river channel. We examined FPOM composition and biomass in the Colorado River, Arizona below Glen Canyon Dam along a 350 km reach during 15 collection mps over four years. Lotic zooplankton and detritus components were positively correlated with distance downriver from the dam, increased discharge, and near-shore habitats versus mid-channel locations. Lentic zooplankton also increased at higher discharges and in near-shore habitats but was negatively correlated with distance downriver. There is evidence the near-shore habitat provides a more stable environment than the mainstem for invertebrates which may enhance rearing and development of lentic zooplankton.

Dam tailwaters compound the effects of reservoirs on the longitudinal transport of organic carbon in an arid river

“…These highly altered physical processes result in increased primary production in tailwaters relative to the unaltered or pre-dam river (Davis et al, 2011). Such high production can increase transported POC and DOC (Webster et al, 1979;Perry and Perry, 1991;Lieberman and Burke, 1993;Benenati et al, 2001). Tailwater POC may consist of sloughed algae from production within the river reach (Webster et al, 1979;Perry and Perry, 1991).…”