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

Abstract

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.