Regulated Rivers-research & Management最新文献

{"title":"The effects of drying and re-flooding on the sediment and soil nutrient dynamics of lowland river-floodplain systems: A synthesis","authors":"D. Baldwin, A. Mitchell","doi":"10.1002/1099-1646(200009/10)16:5<457::AID-RRR597>3.0.CO;2-B","DOIUrl":"https://doi.org/10.1002/1099-1646(200009/10)16:5<457::AID-RRR597>3.0.CO;2-B","url":null,"abstract":"Lowland river–floodplain systems are characterized by a high degree of variability in both the frequency and period of inundation of various parts of the floodplain. Such variation should profoundly affect the processes underlying nutrient transformations in these systems. This paper explores the effect of various hydrologic regimes on nutrient cycles. Partial drying of wet (previously inundated) sediments will result in an increased sediment affinity for phosphorus and will produce a zone for nitrification coupled with denitrification. Hence, partial drying may reduce the availability of nitrogen (N) and phosphorus (P). Conversely, complete desiccation of sediments may lead to the death of bacteria (and subsequent mineralization of N and P), a decrease in the affinity of P for iron minerals, a decrease in microbial activity and a cessation of all anaerobic bacterial processes (e.g. denitrification). Colonization of exposed sediments by terrestrial plants may lead to N and P moving from the sediments to plant biomass. Re-wetting of desiccated soils and sediments will result in an initial flush of available N and P (which can be incorporated into bacterial or macrophyte biomass), coupled with an increase in bacterial activity, particularly nitrification. Inundation of floodplain soils will result in the liberation of C, N and P from leaf litter and floodplain soils. This will result in an increase in productivity, which ultimately may lead to the onset of anoxia in floodplain soils and, consequently, an increase in anoxic bacterial processes such as P release and denitrification. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134493017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modern and historical variation in aquatic macrophyte cover of billabongs associated with catchment development","authors":"R. Ogden","doi":"10.1002/1099-1646(200009/10)16:5<497::AID-RRR600>3.0.CO;2-Y","DOIUrl":"https://doi.org/10.1002/1099-1646(200009/10)16:5<497::AID-RRR600>3.0.CO;2-Y","url":null,"abstract":"Visual estimates of macrophyte cover in Murray and Ovens River billabongs were unrelated to farming and regulation activities, but were positively related to the ratio of Chydoridae to total Cladocera in assemblages of skeletal remains from surface sediments. This ratio (%CHYD) was thus used as a surrogate for macrophyte cover in a palaeoecological analysis. Values of %CHYD were lower in sediments deposited after European settlement than in the pre-settlement parts of sediment cores from three relatively large deep billabongs, and two moderately-sized billabongs, reflecting an historical contraction of the littoral zone in these billabongs. No evidence of a contraction in the littoral macrophyte zone was found in historical records from the two smallest billabongs, although the records were of poorer quality. Visual estimates of macrophyte cover confirmed that macrophytes were generally found in small or shallow billabongs, and that large deep billabongs were macrophyte poor. The timing and spatial pattern of the historical decline in macrophytes implicates an early farming activity as the cause. ‘Control’ billabongs, at present remote from farming centres, have evidence of historical farm impacts which may explain why visual estimates of macrophyte cover and farming are unrelated. Use of the floodplain by farmers may have declined recently, and the historical pattern of macrophyte cover suggests that a naturally stable state of algal dominance has prevented macrophytes from recolonizing large deep billabongs. Evaluations of the role of billabongs in river–floodplain functioning and river–floodplain management strategies must take into account the historical impacts of farming on macrophyte cover. Methods for assessing billabong health that rely on comparisons of affected and non-affected sites (cf. RIVPACS; Wright, 1995) will not work in this region. Attempts to rehabilitate rivers through environmental flows will fail unless steps are taken to remedy farm impacts. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125039924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The response of macroinvertebrates to inundation in floodplain wetlands: A possible effect of river regulation?","authors":"G. Quinn, T. J. Hillman, R. Cook","doi":"10.1002/1099-1646(200009/10)16:5<469::AID-RRR598>3.0.CO;2-1","DOIUrl":"https://doi.org/10.1002/1099-1646(200009/10)16:5<469::AID-RRR598>3.0.CO;2-1","url":null,"abstract":"A large number of permanent and temporary wetlands are associated with the lowland rivers in south-eastern Australia. Regulation of these rivers for irrigated agriculture has probably increased the temporary nature of some wetlands because the reduced frequency of overbank flows causes them to remain dry for longer. The responses of macroinvertebrate assemblages (species composition and abundance) to inundation in permanent and temporary wetlands on the floodplain of the unregulated Ovens River were examined, and these responses were compared with those from permanent and temporary wetlands in the Barmah-Millewa forest of the regulated River Murray. The compositions of macroinvertebrate assemblages in permanent wetlands could not be distinguished from those of temporary wetlands on the Ovens after inundation, although changes in abundance of some taxa (especially chironomids) meant that the assemblages in permanent wetlands differed significantly before and after flooding. In contrast, after inundation, permanent and temporary wetlands in the Barmah-Millewa forest differed significantly and this difference was sustained through time. This different response of macroinvertebrate assemblages on the two floodplains may be an effect of regulation, although other explanations, such as differences between the floodplains in the mechanism of inundation and historical water regimes, or climatid differences between years, may also be important. Further studies should include concurrent sampling on a wider range of regulated floodplains and experiments manipulating water allocations to wetlands, to test specific hypotheses about the effects of water regime on biota.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"351 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122176401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fish larvae and the management of regulated rivers","authors":"P. Humphries, P. S. Lake","doi":"10.1002/1099-1646(200009/10)16:5<421::AID-RRR594>3.0.CO;2-4","DOIUrl":"https://doi.org/10.1002/1099-1646(200009/10)16:5<421::AID-RRR594>3.0.CO;2-4","url":null,"abstract":"Alterations to the natural hydrologic regime in regulated rivers can disrupt cues that initiate the maturation and spawning of riverine fish, or they can change the conditions which are suitable for the recruitment of larvae into juvenile populations. Observations of fish larvae have the potential to provide insights into the effects of flow regulation, showing whether it has had a greater impact on fish by preventing spawning or by reducing or eliminating recruitment. We investigated historical and current records of native fish in the highly regulated Campaspe River and the moderately regulated Broken River, Murray-Darling Basin, Australia, and compared these with the results from sampling of fish larvae over three consecutive years to assess the likely impact that river regulation has had on fish populations in lowland Australian rivers. Of the 12 native species of fish that have been recorded historically from the Campaspe River, eight still occur, generally in low abundance, but only three of these were recorded as larvae in this experiment. From recent records, ten native fish species are extant in the Broken River from a suite of 15 that have been recorded there; of these, nine were collected as larvae. The presence of Murray cod larvae in this river was a significant finding. Thus, the less regulated Broken River is in a much healthier state than the Campaspe River. The results of sampling in both rivers indicated that most species of fish spawned each year, despite high inter-annual variation in antecedent hydrological conditions. This suggests that for the species present in these two rivers, the hydrology (pattern of daily discharge) during the winter and spring preceding breeding was unlikely to be a cue for final maturation and spawning. These findings are only preliminary, but they may show that river regulation has had more of an impact on post-spawning recruitment than on prevention of spawning. This has important implicatons for the remediation of the effects of river regulation, with targeting of recruitment processes and the factors influencing these, a priority. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127924078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of livestock on riparian zone vegetation in an Australian dryland river","authors":"A. Robertson, R. W. Rowling","doi":"10.1002/1099-1646(200009/10)16:5<527::AID-RRR602>3.0.CO;2-W","DOIUrl":"https://doi.org/10.1002/1099-1646(200009/10)16:5<527::AID-RRR602>3.0.CO;2-W","url":null,"abstract":"Vegetation structure and composition and the mass of components of organic detritus were assessed in paired areas, with and without stock access, at six sites. The study revealed that grazing has altered and continues to alter the structure and function of the riparian landscape in the Murrumbidgee River and its tributaries in southeastern Australia. Seedlings and saplings of the dominant Eucalyptus tree species were up to three orders of magnitude more abundant in areas with no stock access, and the biomass of groundcover plants was an order of magnitude greater in areas with no stock access at all sites. Plant species richness did not differ between areas with and without stock access when the ameliorating effect of canopy tree density was taken into account, but plant community composition differed significantly between areas at all sites. Coarse particulate organic matter and terrestrial fine woody debris were consistently more abundant in areas without stock. In-stream fine and coarse woody debris was more abundant in areas without stock at mainstream sites, but not in tributaries. The percentage of bare soil was greater in areas with stock access at all sites. Differences between areas with and without stock access were generally most pronounced at sites where the riparian zone had been excluded from stock access for more than 50 years. The effects of livestock on vegetation and components of detritus have a significant influence on the function of riparian zones. Efforts to restore river health that focus solely on reducing the impact of regulated flows may be nullified if livestock grazing is not considered as part of river ecosystem management. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130688849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Management strategies for cyanobacterial blooms in an impounded lowland river","authors":"I. Webster, B. Sherman, M. Bormans, Gary J. Jones","doi":"10.1002/1099-1646(200009/10)16:5<513::AID-RRR601>3.0.CO;2-B","DOIUrl":"https://doi.org/10.1002/1099-1646(200009/10)16:5<513::AID-RRR601>3.0.CO;2-B","url":null,"abstract":"The incidence of blooms of the toxic cyanobacterium Anabaena circinalis in the major rivers of the Murray–Darling Basin has been strongly related to river discharge, because they are more prevalent during times of low flows. This study into the causes of cyanobacterial blooms in Maude Weir pool on the Murrumbidgee River demonstrates that for Anabaena blooms to form, the water column needs to be persistently stratified, a condition that occurs only during times of low discharge. Based on the relationship between discharge, stratification, and bloom formation, four strategies that might be implemented to minimize the occurrence or impacts of cyanobacterial blooms in weir pools are suggested. These strategies include setting a minimum discharge, pulsing the discharge, changing the discharge height, and altering the depth of water withdrawal. These strategies are evaluated in turn using results from the field study and from the predictions of a numerical model of the weir pool system. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125282191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclic perturbation of lowland river channels and ecological response","authors":"F. D. Shields, S. Knight, C. M. Cooper","doi":"10.1002/1099-1646(200007/08)16:4<307::AID-RRR582>3.0.CO;2-2","DOIUrl":"https://doi.org/10.1002/1099-1646(200007/08)16:4<307::AID-RRR582>3.0.CO;2-2","url":null,"abstract":"Certain lowland streams have experienced prehistorical and historical cycles of aggradation, occlusion, degradation, headward incision, and renewed aggradation. Historical cycles appear to be related to human activities. A case study is presented of the Yalobusha River in Mississippi with emphasis on the effects of blockage and removal on aquatic habitats and fish. The adjacent Skuna River, which was channelized and unblocked, was used in space for time substitution to infer effects of blockage removal on the Yalobusha. Variables describing physical aquatic habitat and fish were sampled from three groups of river reaches: unblocked channelized, channelized and blocked, and naturally sinuous. Fish collections were used to compute six indicators of ecological integrity. At baseflow, mean water depths were an order of magnitude lower in the unblocked channelized stream than for the others. In-channel aquatic habitat volume per unit valley length was 5, 85, and 283 m 3 /m for the channelized, blocked channelized, and natural reaches, respectively. Mean values for all six ecological indicators were lowest for the channelized group. Species richness was greatest for the channelized blocked reach. The ecological indicators displayed gradients in response to the range of observed physical conditions. Management of corridors susceptible to the cycle described above should involve a blend of measures designed to conserve higher quality habitats.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124403284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advection, growth and nutrient status of phytoplankton populations in the lower River Murray, South Australia","authors":"P. Baker, J. Brookes, M. Burch, H. Maier, G. Ganf","doi":"10.1002/1099-1646(200007/08)16:4<327::AID-RRR576>3.0.CO;2-Q","DOIUrl":"https://doi.org/10.1002/1099-1646(200007/08)16:4<327::AID-RRR576>3.0.CO;2-Q","url":null,"abstract":"To investigate the link between river flow, nutrient availability and development of algal blooms, growth rates of the major phytoplankton species were examined in situ in the lower River Murray, South Australia over the 1994/1995 summer. Eight sites were selected over a 54 km reach between Lock 1 and Nildottie and growth rates estimated by monitoring mean cell density in time-aligned parcels of water as they travelled downstream. Discharge at Lock 1 during the period of study (3000–5000 ML day−1) typified summer entitlement flows to South Australia. A large, shallow floodplain lake (lagoon), with an hydraulic connection to the river, supported a large population of cyanobacteria in summer, but inputs to the main channel did not substantially affect the abundance and composition of river phytoplankton. Mean net growth rates of Anabaena circinalis and A. flos-aquae f. flos-aquae were 0.132 and 0.176 day−1, respectively, although individual rates varied from positive to negative. In contrast, the mean growth rate of the filamentous diatom Aulacoseira granulata was −0.15 day−1, reflecting a decrease in population size with advection downstream. Mean cell densities of the three species did not exceed 5000 cells mL−1 throughout the study. Growth bioassays conducted in the laboratory indicated that nitrogen was often the nutrient limiting algal growth, although it was not established whether nitrogen was limiting in situ. A conceptual model is presented, linking these findings with those of other work on the lower River Murray, to summarize the physical and chemical environmental factors governing the abundance of cyanobacteria in this reach of the river. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128119880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Options for rehabilitation of Australia's Snowy River: an economic perspective.","authors":"J. Pigram","doi":"10.1002/1099-1646(200007/08)16:4<363::AID-RRR610>3.0.CO;2-I","DOIUrl":"https://doi.org/10.1002/1099-1646(200007/08)16:4<363::AID-RRR610>3.0.CO;2-I","url":null,"abstract":"The Snowy Mountains Scheme in southeast Australia provides a good example of the extensive changes that can occur in streams from which water is transferred. The Scheme, now 50 years old, diverts large amounts of water from the Snowy River inland to generate hydro-electricity and to supply water for irrigation. In recent years, growing criticism of the degraded condition of the Snowy River has prompted a number of investigations into the feasibility of providing increased flows in the river and of rehabilitation of the stream environment. A recent Snowy Water Inquiry recommended the partial restoration of streamflow in the Snowy River to 15% of natural levels. However, the Snowy Water Inquiry noted the considerable trade-offs involved in terms of hydro-electricity generation and irrigation, at an overall estimated cost of Australian dollars (A$) 194 million (approximately US$125 million). All monetary values are at 1998 levels (A$ converted to US$ at 0.63). The preferred option identified satisfied none of the interested parties and the matter remains unresolved. Given the complexity of the issue, the Snowy Water Inquiry must be seen as only an initial step in a lengthy process of balancing socioeconomic costs and benefits, and ecological, legal and political considerations, before rehabilitation of the Snowy River can be achieved. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114707327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of mainstem spawning habitats for two populations of fall chinook salmon in the Columbia River basin.","authors":"D. Dauble, D. Geist","doi":"10.1002/1099-1646(200007/08)16:4<345::AID-RRR577>3.0.CO;2-R","DOIUrl":"https://doi.org/10.1002/1099-1646(200007/08)16:4<345::AID-RRR577>3.0.CO;2-R","url":null,"abstract":"Extensive hydroelectric development in the Columbia River system has eliminated most mainstem riverine habitat available for spawning by fall chinook salmon (Oncorhynchus tshawytscha). The two remaining populations, Hanford Reach, Columbia River and Hells Canyon Reach, Snake River, are separated geographically and their status is markedly different. Annual escapements to Hanford Reach have averaged approximately 80 000 adults, while the Snake River run size has declined to <1500 adults over the past 10 years. We compared their spawning habitat characteristics over a range of measurement scales, as a means to identify strategies for rebuilding the weak Snake River population. Physical habitat characteristics of redds were similar for both study areas. Redd locations were correlated with channel characteristics, such as braiding and sinuosity. Several differences between the two spawning areas were identified at the watershed scale: the Hells Canyon Reach had a much steeper longitudinal gradient, was largely confined by bedrock, and had a more variable flow regime. These features are controlling variables that operate at the reach-scale to limit the availability and size of substrate and other conditions that influence egg deposition and incubation survival. Geomorphological characteristics of the two study sites are sufficiently different to indicate that the production potential of the Hells Canyon Reach population is markedly lower than that of the Hanford Reach population. Copyright © 2000 John Wiley & Sons, Ltd.","PeriodicalId":306887,"journal":{"name":"Regulated Rivers-research & Management","volume":"239 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131458383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}