Major flood disturbance alters river ecosystem evolution

Milner, Alexander M.; Robertson, Anne L.; McDermott, Michael J.; Klaar, Megan; Brown, Lee E.

doi:10.1038/nclimate1665

Cited by 66 publications

(69 citation statements)

References 24 publications

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“…Flow is a major determinant of physical habitat in streams (Poff and Zimmerman, ), which in turn has profound effects on the structure and function of living communities, as reported for benthic algae (Biggs and Smith, ), invertebrates (Milner et al ., ), and fish (Xenopoulos et al ., ). Consequently, the alteration of flow regimes as a result of increasing water abstraction and/or climate change is a critical factor for the decline in freshwater biodiversity (Dudgeon et al ., ; Larned et al ., ; Vorosmarty et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Glacial flood pulse effects on benthic fauna in equatorial high-Andean streams

et al. 2013

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Equatorial glacier‐fed streams present unique hydraulic patterns when compared to glacier‐fed observed in temperate regions as the main variability in discharge occurs on a daily basis. To assess how benthic fauna respond to these specific hydraulic conditions, we investigated the relationships between flow regime, hydraulic conditions (boundary Reynolds number, Re*), and macroinvertebrate communities (taxon richness and abundance) in a tropical glacier‐fed stream located in the high Ecuadorian Andes (> 4000 m). Both physical and biotic variables were measured under four discharge conditions (base‐flow and glacial flood pulses of various intensities), at 30 random points, in two sites whose hydraulic conditions were representative to those found in other streams of the study catchment. While daily glacial flood pulses significantly increased hydraulic stress in the benthic habitats (appearance of Re* > 2000), low stress areas still persisted even during extreme flood events (Re* < 500). In contrast to previous research in temperate glacier‐fed streams, taxon richness and abundance were not significantly affected by changes in hydraulic conditions induced by daily glacial flood pulses. However, we found that a few rare taxa, in particular rare ones, preferentially occurred in highly stressed hydraulic habitats. Monte‐Carlo simulations of benthic communities under glacial flood reduction scenarios predicted that taxon richness would be significantly reduced by the loss of high hydraulic stress habitats following glacier shrinking. This pioneer study on the relationship between hydraulic conditions and benthic diversity in an equatorial glacial stream evidenced unknown effects of climate change on singular yet endangered aquatic systems. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 97%

Glacial flood pulse effects on benthic fauna in equatorial high-Andean streams

et al. 2013

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“…The flow regime of a river is fundamental in determining its ecological characteristics (Power et al ., ; Poff et al ., ; Bunn & Arthington, ; Olden & Poff, ; Allan & Castillo, ; Naiman et al ., ). Flow influences the abundance and distribution of lotic species (Allan & Castillo, ) both indirectly through physical habitat modification and directly through stimulation of biotic responses (Bunn & Arthington, ; Milner et al ., ) [e.g. movement (James, Dewson & Death, ) and spawning (Górski et al ., )].…”

Section: Introductionmentioning

confidence: 99%

A critical analysis of regulated river ecosystem responses to managed environmental flows from reservoirs

et al. 2014

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Summary The flow regime of a river is fundamental in determining its ecological characteristics. Impoundment of rivers has been documented to severely impact the natural flow regime, resulting in abiotic and biotic changes in downstream ecosystems. Contemporary water legislation is driving increasing concern among environmentalists and water resource managers with respect to how these impacts can be mitigated. This has stimulated research aimed at assessing the relationship between reservoir outflow modification (i.e. managed environmental flows) and downstream ecosystem responses. We carried out a critical review and synthesis of the global literature concerning post‐impoundment reservoir outflow modification and associated downstream biotic and abiotic responses. Seventy‐six studies published between 1981 and 2012 were analysed. In contrast to previous studies of this subject, we systematically assessed the methodological quality of research to identify strengths and weaknesses of the approaches. We also undertook a novel quantification of ecosystem responses to flow modification, thus enabling identification of priorities for future research. We identified that: (i) there was a research bias towards North American and Western European studies; (ii) the majority of studies reported changes in flow magnitude (e.g. artificial floods) and primarily focused on traditionally monitored ecological groups (e.g. fish); (iii) relationships between flow, biota (e.g. macroinvertebrates) and water quality (e.g. electrical conductivity and suspended solids concentration) were evident, demonstrating the potential for managed environmental flows to manipulate river ecosystems; (iv) site‐specific factors (e.g. location, climate) are likely to be important as some ecosystem responses were inconsistent between studies (e.g. fish movement in response to increases in flow magnitude); and (v) quality of study design, methodological and analytical techniques varied, and these factors may have contributed to the reported variability of ecosystem response. To advance scientific understanding and guide future management of regulated flow regimes, we highlight a pressing need for: (i) diversification of study locations as well as flow modification and ecosystem response types assessed; (ii) a focus on understanding flow–ecosystem response relationships at regional scales; (iii) further quantitative studies to enable robust statistical analyses in future meta‐analyses; and (iv) robust monitoring of flow experiments and the use of contemporary statistical techniques to extract maximum knowledge from ecological response data.

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“…Stream flow and stream temperature affect production and timing of benthic fauna that forms much of the food base for freshwater fishes in lowland forest streams (Wipfli 1997;Wipfli and Baxter 2010). Changes in flow, temperature, and nutrient dynamics in freshwater ecosystems influence fish abundance across life-history stages (Bryant 2009 Milner et al 2013).…”

Section: Implications For Freshwater Hydrology and Fishesmentioning

confidence: 99%

Climate change implications in the northern coastal temperate rainforest of North America

et al. 2015

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We synthesized an expert review of climate change implications for hydroecological and terrestrial ecological systems in the northern coastal temperate rainforest of North America. Our synthesis is based on an analysis of projected temperature, precipitation, and snowfall stratified by eight biogeoclimatic provinces and three vegetation zones. Five IPCC CMIP5 global climate models (GCMs) and two representative concentration pathways (RCPs) are the basis for projections of mean annual temperature increasing from a current average (1961-Climatic Change (2015 1990) of 3.2°C to 4.9-6.9°C (5 GCM range; RCP4.5 scenario) or 6.4-8.7°C (RCP8.5), mean annual precipitation increasing from 3130 mm to 3210-3400 mm (3-9 % increase) or 3320-3690 mm (6-18 % increase), and total precipitation as snow decreasing from 1200 mm to 940-720 mm (22-40 % decrease) or 720-500 mm (40-58 % decrease) by the 2080s (2071-2100; 30-year normal period). These projected changes are anticipated to result in a cascade of ecosystem-level effects including: increased frequency of flooding and rain-on-snow events; an elevated snowline and reduced snowpack; changes in the timing and magnitude of stream flow, freshwater thermal regimes, and riverine nutrient exports; shrinking alpine habitats; altitudinal and latitudinal expansion of lowland and subalpine forest types; shifts in suitable habitat boundaries for vegetation and wildlife communities; adverse effects on species with rare ecological niches or limited dispersibility; and shifts in anadromous salmon distribution and productivity. Our collaborative synthesis of potential impacts highlights the coupling of social and ecological systems that characterize the region as well as a number of major information gaps to help guide assessments of future conditions and adaptive capacity.

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Major flood disturbance alters river ecosystem evolution

Cited by 66 publications

References 24 publications

Glacial flood pulse effects on benthic fauna in equatorial high-Andean streams

Glacial flood pulse effects on benthic fauna in equatorial high-Andean streams

A critical analysis of regulated river ecosystem responses to managed environmental flows from reservoirs

Climate change implications in the northern coastal temperate rainforest of North America

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