Abundant hyporheic (interstitial riverine) biota were collected within a grid of shallow (10m) wells as far as 2.5 kilometers from the channel of the Flathead River, MT, which confirms a greatly extended spatial dimension in river ecology. This research addresses several community level hypotheses in an attempt to describe and differentiate the hyporheic fauna (microbes and invertebrates) and the functional role of the hyporheic zone in influencing biota and processes in the benthos (channel) of alluvial rivers. Flathead River hyporheic Plecoptera are very abundant and intraspecific selection pressures resulting in reproductive isolation is suggested by the presence of polymorphic populations. The project will also involve the reproductive strategies of these stoneflies. The energy base of the apparently complex hyporheic food web is unknown, and it is hypothesized that interstitial entrainment of riverine detritus (POM) is important. Discharge from the hyporheic is apparently a significant source of nitrate and biologically active phosphorus in the river. If these nutrients are derived from communition of riverine POM within the hyporheic food web, then the research will lay a new conceptual foundation for eosystem-level questions in river ecology.
