The impact of drought events in 1976 and 1997 on the macroinvertebrate fauna of a chalk stream

Wright, J. F.; Gunn, R.J.M.; Winder, J.M.; Wiggers, R.; Kneebone, N. T.; Clarke, Ralph T.

doi:10.1080/03680770.2001.11901856

Cited by 4 publications

(8 citation statements)

References 5 publications

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“…Lowest family richness varied with habitat and site on the Kennet with 1998 featuring fairly prominently, as previously noted for replicate mean richness. In contrast at Bagnor, lowest family richness for macrophyte (also macrophyte and gravel combined) occurred in 1997, the drought year, as previously noted in Wright et al (2002a).…”

Section: Discussionmentioning

confidence: 48%

Impact of major changes in flow regime on the macroinvertebrate assemblages of four chalk stream sites, 1997–2001

Wright

Clarke

Gunn

et al. 2004

River Research & Apps

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The macroinvertebrate assemblages of three unshaded sites on the River Kennet and one shaded site on the River Lambourn in Berkshire, England, were sampled in summer 1997-2001. Quantitative samples were taken on gravel and on the dominant macrophyte at each site in each year and abundance data were recorded for 57 families of macroinvertebrates. The study commenced during a major drought (1997), but in subsequent years discharge prior to sampling was much higher, culminating in the exceptionally high flows of spring 2001. Both family richness and abundance varied significantly in relation to site, habitat and year. Multidimensional scaling ordination, based on Bray-Curtis dissimilarities, also displayed significant differences between sites, habitats and years. Differences in composition between the Kennet sites were partly due to longitudinal zonation whilst on the Lambourn, faunal differences resulted from shading and the addition of families from nearby habitats, including marginal vegetation. Major changes took place in family composition and abundance between the drought year of 1997 and 1998, indicating that faunal recovery from drought was rapid. Thereafter, faunal changes between 1998 and 2000 were relatively limited. In 2001, following the prolonged period of exceptionally high discharge, overall family richness peaked on both habitats at the three Kennet sites and family abundance reached peak or second highest values on all four sites and both habitats. Thus, the recent high discharge regimes experienced by these perennial chalk stream sites have had no immediate detrimental consequences for the macroinvertebrate assemblages.

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Section: Discussionmentioning

confidence: 48%

Impact of major changes in flow regime on the macroinvertebrate assemblages of four chalk stream sites, 1997–2001

Wright

Clarke

Gunn

et al. 2004

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“…Berula retained high family richness from one sampling period to the next with no significant differences between sampling periods ( t = −0.80; P = 0.446). Nevertheless, lower family richness values occurred in the drought years of 1976 and 1997 (Wright et al ., 2002). Highest richness for Berula (41 families) occurred in 1979 when the area of macrophyte was low (Table 1) and may indicate heavy exploitation of a preferred habitat.…”

Section: Total Family Richness For Each Habitat and For The Sitementioning

confidence: 99%

“…Simuliidae were more abundant in 1975–79 because the high discharge years also provided a large surface area of macrophyte from which the larvae could filterfeed. In contrast, the Chironomidae occurred at very high densities under the drought conditions of 1976 and exploited epiphytic algae (Wright et al ., 2002).…”

Section: Changes In the Functioning Of The Systemmentioning

confidence: 99%

“…Some of the consequences of the 1976 and the 1996/97 drought have been examined in Wright et al . (2000) and Wright et al . (2002).…”

Section: Introductionmentioning

confidence: 99%

“…The Agency required information on whether the flora and fauna had been affected and, if so, how long it would take the system to recover. Some of the consequences of the 1976 and the 1996 ⁄ 97 drought have been examined in Wright et al (2000) and Wright et al (2002).…”

Section: Introductionmentioning

confidence: 99%

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Response of the flora and macroinvertebrate fauna of a chalk stream site to changes in management

et al. 2003

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SUMMARY 1. Temporal changes in a series of habitats and their macroinvertebrate assemblages were examined on a 50‐m section of a chalk stream in Berkshire, England between June 1975–79 and June 1997–2001. 2. The site was part of a trout fishery in 1975–79, when river management included instream weed cutting together with control of bankside trees and riparian vegetation. Management ceased in the 1980s and by 1997–2001, the site was heavily shaded by trees and riparian vegetation. 3. The mean area of instream macrophytes decreased by 50% between the first and second sampling period. In contrast, gravel and silt increased and invading marginal vegetation formed a new habitat. 4. Changes in macroinvertebrate family richness between sampling periods were scale dependant. Although there were, on average, significantly more families in individual replicates in 1975–79 than in 1997–2001, total family richness for the site in each year did not differ significantly between sampling periods. 5. Sixty families of macroinvertebrates were recorded during the study, 50 in both sampling periods, 53 in 1975–79 and 57 in 1997–2001. This small increase in site family richness may be due to the invading marginal plants. 6. Total macroinvertebrate abundance was significantly lower in the second sampling period. A major drought in 1976 resulted in significantly higher densities of macroinvertebrates, partly through the exploitation of epiphytic diatoms by chironomid larvae. A drought in 1997 failed to elicit a similar response because of the limited macrophytes and diatoms under heavy shading by trees and marginal vegetation. 7. Significant increases in important shredders and decreases in some scrapers between the early and later sampling years largely reflected changes in available food resources. 8. Whereas macroinvertebrate family richness has been conserved under the recent ‘no management’ regime, the site is now less attractive as a fishery because of poor access and lower densities of some macroinvertebrates taken by brown trout.

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Un modelo conceptual sobre el funcionamiento de los ríos mediterráneos sometidos a perturbaciones naturales (riadas y sequías)

Gutiérrez¹,

Alonso²,

Soler³

et al. 2007

Limnetica

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A conceptual model on the function of Mediterranean rivers subjected to natural disturbances (flash-floods and droughts)The Mediterranean regions are prone to suffer extraordinary flash-floods and prolonged droughts. Between these extreme events, there are small floods and droughts that are more common and more predictable. These smaller floods and droughts, along with the others mentioned before generate an extraordinarily complex temporal hydrological picture whose affects have been partly described by different authors, including those affecting the human population. The information compiled during nearly two decades by the group of Ecology of Continental Waters of the University of Murcia, about the effects of these events on rivers of the Segura River Basin, allows for elaborating a conceptual model about the function of several physical, physico-chemical, and biological parameters in rivers in the southwest, in particular and Mediterranean rivers in general.

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The impact of drought events in 1976 and 1997 on the macroinvertebrate fauna of a chalk stream

Cited by 4 publications

References 5 publications

Impact of major changes in flow regime on the macroinvertebrate assemblages of four chalk stream sites, 1997–2001

Impact of major changes in flow regime on the macroinvertebrate assemblages of four chalk stream sites, 1997–2001

Response of the flora and macroinvertebrate fauna of a chalk stream site to changes in management

Un modelo conceptual sobre el funcionamiento de los ríos mediterráneos sometidos a perturbaciones naturales (riadas y sequías)

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