A preliminary investigation on effects of fluctuating flows on invertebrates of the Hawea River, a large regulated river in New Zealand

Abstract

An experiment with flow changing at 3, 9, and 18 m 3 s -1 h -1 on consecutive days failed to produce any measurable effect on benthic invertebrates in the regulated Hawea River, New Zealand, but did result in increased numbers of drifting chironomid larvae, trichopteran larvae, and oligochaetes compared to days when flow was stable. Drift densities were at least as high on the day flow changed at 3 m 3 s -1 h -1 (minimum flow 15 m 3 s -1 , maximum flow 30 m 3 s -1 ) as on subsequent days when flow changed at 9 and 18 m 3 s~' h -1 (minimum flows both 15 m 3 s -1 , maximum flows 60 and 105 m 3 s~' respectively) indicating that rapid rates of change of flow may not necessarily cause more benthic invertebrates to enter the drift than slow rates of change. Fluctuating flows resulted in more animals entering the drift at a site 5 km below a control dam than at a site 0.8 km below

Influence of peak flow changes on the macroinvertebrate drift downstream of a Brazilian hydroelectric dam

“…Chance and Craig (1986) also reported that Simuliidae larvae had a lower risk of being displaced by moderate flow changes because of their hydrodynamic and morphological adaptations to cling to the substrate, which is much less true for Hydropsychidae. Chironomidae drift densities increased with increased flow fluctuations in both wet and dry seasons, corroborating the results of Irvine and Henriques (1984) but differing from the results of Gislason (1985) and Troelstrup and Hergenrader (1990).…”

Characteristics of Lotic Ecosystems and Consequences for Future Research Directions

“…III.l, Elliott 1984b) field manipulations of, for example, discharge (Gore 1977, Irvine andHenriques 1984), woody debris (Angermeier and Karr 1984), or watershed vegetation (Gurtz and Wallace 1984) promise faster success than the "observe and wait strategy".…”

Effects of a multi-year experimental flood regime on macroinvertebrates downstream of a reservoir

“…The lateral displacement of water is reduced in confined channels relative to unconfined channels (Badri et al, 1987), causing a high degree of scouring and the dislodgement and drifting of organisms (Irvine and Henriques, 1984;Imbert and Perry, 2000). Lytle (2000) suggested many of these drifting organisms are delivered downstream, although many others may accumulate in slow flow areas, or shorelines (Winterbottom et al, 1997).…”