The macroinvertebrates and fish of a Colorado stream during a period of fluctuating discharge

Abstract

1. During a 2-year study of the fish and macroinvertebrates of a third-order montane stream, a severe drought in thefirst year resulted in a temporary cessation of surface flow. Flow was continuous during the second year.2. Some taxa (e.g. Ophiogomphus severus) exhibited higher density during the drought year, others declined in abundance during low flow (e.g. Baelis spp.), whereas a few (e.g. Tricorythodes minuius) appeared unaffected. Total macroinvertebrate density decreased by 5{)% during the low flow year compared to the normal flow year. Mayflies were most severely affected, but also exhibited the most dramatic recovery.3. The collector-gatherer functional feeding group was abundant only during the normal flow year, whereas shredders and predators exhibited increased relative abundance during low flow.4. Fish populations were severely reduced in the low flow year. However, fishes rapidly invaded the area following resumption of normal flow.

Effects of stream diversion on riffle macroinvertebrate communities in a Maui, Hawaii, stream

“…Most importantly, both disturb the natural flow regime of the stream system, thus reducing flow volume and habitat availability (Canton et al, 1984;Cowx et al, 1984;Benbow, 1999). A reduction in stream flow can also impact food availability, depending on the species and functional feeding group (Extence, 1981;Canton et al, 1984;Cowx et al, 1984;Allen, 1995). Fluctuations in macroinvertebrate populations can also depend on the mobility of an organism.…”

Using commercial catch statistics to detect habitat bottlenecks in large lowland rivers

“…Impacts of extreme floods and droughts on fish larvae and juveniles are well documented (Canton et al, 1984;Harvey, 1987;Pearsons et al, 1992;Jackson, 1993;Labbe and Fausch, 2000;Schlosser et al, 2000;Bischoff and Wolter, 2001;Magoulick and Kobza, 2003;Matthews and Marsh-Matthews, 2003). However, testing of the habitat bottleneck concept with respect to its effects on the level of fish assemblages has been limited.…”

“…On the one hand, large floodplains inundated by high floods serve as important feeding areas for fish and nurseries for juveniles (Welcomme, 1979;Poff and Allan, 1995;Schiemer et al, 1995Schiemer et al, , 2001Grossman et al, 1998;Jungwirth et al, 2000), while on the other hand fish larvae and juveniles may become washed out because of their low swimming performance (Harvey, 1987;Pearsons et al, 1992;Jackson, 1993;Bischoff and Wolter, 2001). By comparsion, droughts may favour fish species reproducing at low flow conditions (Humphries et al, 1999;King et al, 2003), although the most frequently demonstrated effects of droughts are declines in population because higher resource competition and predation occur with increasing concentration in the remaining water volume (Canton et al, 1984;Matthews, 1998;Labbe and Fausch, 2000;Schlosser et al, 2000;Lake, 2003;Magoulick and Kobza, 2003;Matthews and Marsh-Matthews, 2003).…”

International Journal of Biology, Vol. 2, No. 1, January 2010, all in one file

“…The pools water becomes acidic at Tori during premonsoon 1998(value-6.16), Dissolve Oxygen (1.6 mg/l), Free Carbondioxide (9.58 mg/l) and high alkalinity (245.7 mg/l). It needs mention here that several workers like Starrett ( 1951), Canton et al (1984), Moore andGeorgy, (1988a,1988b) and Angelo et al(1995), reviewed the effects of late summer reduction in stream flow on fishes emphasizing their crowding and fingerlings crowd in shallow stagnant pools. The present observation in the Damodar River, as stated above, corroborate their findings.…”