Article

River ecology and stream restoration

Authors:
If you want to read the PDF, try requesting it from the authors.

Abstract

Management and restoration of river ecosystems are based on an understanding of the relations between physical, chemical, and biological processes at varying time scales. Often, human activities have accelerated the temporal progression of these processes, resulting in unstable flow patterns and altered biological structure and function of stream corridors. This chapter discusses river ecology, disturbances of the ecology, and restoration strategies.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
Chapter 25 illustrates some of the ways in which fluvial geomorphology can play a role in flood control planning. As in other aspects of flood study, geomorphology provides the critical perspective on fluvial systems over temporal and spatial scales that extend well beyond those considered in local engineering design problems. Channel changes and sediment problems may be ignored by engineering studies, but these are central to any geomorphic analysis. Until mathematical modeling achieves the ability to predict accurately such phenomena from a basis of scientific understanding flood control planners will ignore geomorphological analysis at their peril. -from Editors
Article
Full-text available
Secondary cavity-nesting birds were studied in riparian habitat along the lower Colorado River, Arizona, to determine whether the birds were limited by availability of nest sites in relatively undisturbed habitat. Species differed in cavity use on the basis of size and time, and cavities were a limiting factor on only one of three study areas, but birds were responsive to cavity manipulations. Breeding numbers remained stable on an unmanipulated plot despite increased European starlings Sturnus vulgaris. Some cavity-related aggression occurred, but did not affect breeding numbers or success, because alternate nest sites were available.-from Author
Article
Full-text available
Habitat features and relative abundance of all fish species were estimated in 8.4 km of a small mountain stream system before and 11 months after Hurricane Hugo crossed the southern Appalachians in September 1989. There was no change in the total amount (area) of each habitat type but the total number of habitat units decreased and average size and depth of habitat units increased. Transport and sorting of streambed sediments was evident from the increased proportion of habitat units in which cobbles and small boulders were the most common constit- uents. Large woody debris more than doubled from 228 to 559 pieces/km of stream channel. At the watershed scale, there were only minor changes in the fish community 11 months after the hurricane. Eleven species were found both before and after the storm, and most species were uncommon. Among common species, densities increased in riffles for darters Etheostoma spp., increased in pools for blacknose dace Rhinichthys atratulus, and were largely unaffected for rainbow trout Oncorhynchus mykiss. The results of this case study suggest that the effects of catastrophic disturbances on fish habitat and populations depend on the predisturbance condition of instream and riparian habitat, timing of the disturbance, and life histories of individual species.
Article
Full-text available
The influence of bank vegetation on the stable channel cross-sectional geometry of stable, straight gravel rivers is studied theoretically. Singular perturbation and matched asymptotic expansion techniques are employed to derive the lateral distribution of depth-averaged fluid velocity and the bed shear stress. A condition of sediment incipient motion is imposed at the junctions of the bed and the banks to derive the stable depth, and a formula for resistance to flow is used to obtain the stable width. The theory reveals that a thicker vegetation yields a larger depth and a smaller width. Increasing discharge increases the effect of vegetation. The analysis agrees reasonably well with available field data.
Article
Full-text available
The index of biotic integrity (IBI) integrates 12 measures of stream fish assemblages for assessing water resource quality. Initially developed and tested in the Midwest, the IBI recently was adapted for use in western Oregon, northeastern Colorado, New England, the Appalachians of West Virginia and Virginia, and northern California. The concept also was extended to Louisiana estuaries. In regions of low species richness, the IBI proved difficult to apply and often required extensive modification. Adapting the 1BI to those regions required that metrics be replaced, deleted, or added to accommodate regional differences in fish distribution and assemblage structure and function. Frequently replaced metrics include: proportion of individuals as green sunfish (Lepomis cyanellus), proportion of individuals as insectivorous cyprinids, proportion of individuals as hybrids, and number and identity of sunfish and darter species. The proportion of individuals as top carnivore metric was often deleted. Metrics added include total fish biomass and the number and identity of minnow species. These modifications generally followed the original IBI concept and its theoretical underpinnings. Problems remain in establishing tolerance rankings and scoring criteria, and adjusting scoring criteria for gradient differences in streams of similar size. The IBI holds promise for direct biological monitoring because of its strong ecological foundation and flexibility. Vermont, Tennessee Valley Authority, Ohio, Kentucky, and Illinois have incorporated the IBI into their monitoring or standards programs. The IBI thus serves as a quantitative, biological goal for water resource management.
Article
Full-text available
In interior western North America, many riparian forests dominated by cottonwood and willow are failing to reproduce downstream of dams. We tested the hypothesis that establishment is now prevented by absence of the bare, moist substrate formerly provided by floods and channel movement. Along Boulder Creek, a dammed stream in the Colorado plains, we tested the effects of disturbance (sod removal), irrigation, and addition of seed on the establishment of seedings of plains cottonwood (Populus deltoides subsp.monilifera) and peachleaf willow (Salix amygdaloides). In unirrigated, undisturbed plots, mean cottonwood density was 0.03 seedlings/m2. Irrigation or disturbance alone produced mean cottonwood densities of 0.39 and 0.75 seedlings/m2. Plots that were both irrigated and disturbed produced a mean cottonwood density of 10.3 seedlings/m2. The effects of irrigation and disturbance on cottonwood establishment were significant (P<0.005); added seed had no significant effect (P=0.78). The few cottonwood seedlings in unirrigated plots were in low positions susceptible to scour by future moderate flows. We conclude that cottonwood establishment along Boulder Creek is limited by the scarcity of bare, moist sites safe from future scour. Establishment of peachleaf willow was significantly affected only by disturbance; daily sprinkler irrigation did not provide sufficient moisture to increase survival of this species. Our results demonstrate the feasibility of restoring plains cottonwood forests using natural seedfall, even where only widely scattered adult trees are present. Because use of natural seedfall conserves the genetic makeup of the local population, this method may be preferable to the use of imported cuttings.
Article
Full-text available
Breeding bird populations were studied on seven riparian woodland study plots in north-central Arizona. The densities of breeding birds varied from 193 to 847 pairs per 40 hectares. These differences were, in part, related to the vegetative structure of the habitat. Bird species diversity (BSD) was not correlated with foliage height diversity (FHD) in riparian habitats consisting of one major vegetational component (the cottonwood tree Populus fremontii) where these habitats are bordered by agricultural fields. These areas supported the largest breeding bird populations (847, 612, 512, and 425 pairs per 40 hectares) while areas consisting of a mixed deciduous tree and shrub component (Populus, Platanus, Salix, Acer, Fraxinus, Prosopis, etc.) had smaller populations of breeding birds (322, 312, and 193 pairs per 40 hectares). On the mixed deciduous woodland areas the correlation between BSD and FHD was similar to what others have found in Eastern deciduous forests. The average weights of individual birds were significantly greater on the homogeneous cottonwood areas (⁠X¯ = 46.4 g) than on the mixed deciduous areas (⁠X¯= 22.9 g). Data gathered indicate that two systems of social organization are being maintained. In areas of relatively low population density (mixed deciduous) 57% of the pairs maintained “class A” territories. On areas of relatively high population density (homogeneous cottonwood) only 22% of the pairs exhibited this form of spacing; here, most birds forage freely outside of the riparian habitat. We suggest that the differences in population density and average weights of birds found in the two habitat types are a result of the following: (i) relative productivity of areas adjacent to the riparian habitat, and (ii) degree of intra- and interspecific competition effected by avian populations found breeding in areas adjacent to the riparian habitat.
Article
Two types of fish attractors, one made from vitrified clay pipes and the other from cement blocks and brush, were investigated in Lake Tohopekaliga, Florida. Electrofishing, creel census, and experimental fishing were used to evaluate the effectiveness of attractors in concentrating fish and enhancing fishing success. Both attractors produced significantly higher fishing success than did control areas and were generally superior to the average fishing success elsewhere in the lake. Brush-block attractors yielded a slightly higher success rate than the pipe attractors. Fishing success at attractor sites was highest during the first year after installation. The lower fishing success in subsequent years appeared to have been at least partially the result of a lake level drawdown which temporarily reduced the standing crop of fish and stimulated expansion of the littoral zone into deeper areas which had been devoid of plants. Soybean meal was found to be a supplemental fish attractant which increased fishing success at attractor sites where catch rates had diminished.
Article
The authors describe a model (SALMOD) that simulates freshwater salmonid population dynamics. The model tracks spatially distinct cohorts that originate as eggs and grow as a function of water temperature. Fish remains in the unit in which they emerged, move to nearby units, or emigrate. An example from a Trinity River, California, chinook salmon (Oncorhynchus tshawytscha) population is used. Performance is assessed by a 3 yr calibration and sensitivity to the temporal pattern and amount of flow. Pattern of flow was more important than volume in controlling the number of surviving outmigrants; the best regime was a low flow during early spawning, stable medium flow during most active spawning, variable flow during fry emergence, and high flow thereafter. -from Authors
Article
Human activities, including the construction of the Three Gorges Dam, Gezhouba Dam and other river training projects, are changing the river environment and stream habitat in the Yangtze River in China. As a result, the aquatic organisms, especially, the rare species and fishery fishes with economic value are affected. This paper studies the changing characteristics of the river that affect the aquatic community habitat, such as substrate, water depth, water temperature, water velocity, water quality, etc. Chinese Sturgeons, an anadromous species mainly live in the Yangtze River, are endangered by the construction of dams and other hydraulic projects. Habitat suitability indices for the Chinese Sturgeon are proposed and calculated. Based on the research on the main eco-factors influencing growth and reproduction of the species, ten aquatic eco-factors are analyzed for the habitat suitability indices, including water temperature, water depth, substrate, water velocity, sediment concentration, and egg-predatory fishes. The stream habitat for the Chinese Sturgeon is assessed with the model, which integrates these eco-factors. The model is validated by its application to 12 groups of data, and a habitat suitablity index model for Chinese Sturgeon is presented.
Article
It is not clear that water and habitat quality in the coastal embayments of eastern North America are greatly affected by the quality of water and habitat in the thousands of feeder streams and rivers comprising their watershed. In this paper, I suggest that the quality of streamside forests may be the single most important factor altered by humans that affects the structure and function, and ultimately water quality, of the stream providing water to the coastal embayments. I use comparative data from forested and deforested reachs of streams in a small Piedmont watershed (White Clay Creek) to illustrate chemistry of the water and/or potential effects of streamside forests on: (i) availability of habitat; (ii) the nutrient chemistry of the water; and (iii) the quantitative and qualitative nature of the primary food base (organic detritus and algae) supporting higher trophic levels in streams. Also discussed are the potential role of streamside forests in partially mitigating the flux of sediment and nutrients into aquatic ecosystems, the effects of global warming on stream temperatures, and the deleterious effects on stream organisms of the increased levels of UV radiation associated with global ozone depletion. Current methods and approaches for streamside forest restoration are presented.
Article
Development of a riparian forest on the Great Plains has provided a corridor for movement of forest birds across grasslands that had served as an ecological barrier to dispersal during historical times. Almost 90% of the contemporary avifauna of NE Colorado was not present at the turn of the century. The corridor has resulted in secondary contact of many congeners which currently hybridise on the Great Plains. Implications for management of riparian forest are examined. -from Author
Article
Human activities, especially dam construction and river training projects are changing the river environment and stream habitat in the Yangtze River in China. As a consequence, aquatic organisms, especially, rare species and fishes with economic value are affected. Therefore, it is necessary to study the changing characteristics of the river that affect the aquatic community habitat, such as substrate, water depth, water temperature, velocity, water quality, etc. There are four species of carps in the Yangtze River that have the most importance to the fresh water fishery in China. They are the black carp (Mylopharyngodon piceus), the grass carp (Ctenop haryngodon idellus), the silver carp (Hypoph thai michthys molitrix) and the big-head carp (Aristichyths nobilis), which are the four major Chinese carp Species. A model is developed in this paper of the habitat Suitability Indices for the four major Chinese carp Species. Based on research on the main eco-factors influencing growth and reproduction, 10 main aquatic eco-factors are analyzed, including water temperature; velocity; water depth; dissolved oxygen; un-iomized ammonia; vegetative cover; and amount of pools, backwaters, and marshes. The Suitability Index (SI) curves of the ten eco-factors for these species are obtained. The stream habitat for the carp species is assessed with the model, which integrates these eco-factors. The model is validated by application to 15 groups of data.
Article
Benthic macroinvertebrates are vital in the food chain of aquatic bio-communities. Substrata play an important role in the benthic invertebrate communities, and the characteristics of stream substrata, such as bed material size, heterogeneity and stability, can obviously affect the benthic bio-community. Field investigations were done to study the biodiversity of macroinvertebrates in various stream substrata. Sampling sites differing in bed composition, latitude and climate were selected along the Yangtze River, the Yellow River, the East River, and the Juma River in China. The results show that the benthic community structures found in different substrata clearly differ, while those found in substrata of similar composition and flow conditions but in different macroclimates are quite similar. The study thus demonstrates that the benthic macroinvertebrate community is mainly affected by substrate composition and flow condition, but is generally unaffected by latitudinal position and macroclimate. Biodiversity in different substrata is assessed via several biodiversity indices. Taxa richness of the macroinvertebrate community was found to be highest in hydrophyte-covered cobbles, high in moss-covered bedrock, and relatively low in clay and cobble substrata devoid of plant biomass. Sand substrate is compact and unstable, and no benthic macroinvertebrates were found colonizing this substrate. Aquatic insects account for most of the macroinvertebrates found in these rivers. Different insect representatives dominate in different substrata types: mainly Ephemeroptera larvae were found in cobble and moss-covered bedrock substrata while Chironomidae larvae were found in clay beds. The relation between the number of species in the samples and the sampling area is also analyzed. The results support the species-area power rule. Since the experimental results differed little between surveys using 1m2 and 2m2 sampling areas, 1m2 is suggested as a sufficient minimum sampling area.
Article
The goal of stream restoration managers becomes the enhancement of available habitat for colonizing invertebrates. If preferred habitat types are available to colonizers, a stable macroinvertebrate community can be established and maintained. This chapter will provide the manager with information on the dispersal mechanisms of aquatic invertebrates, measurements of optimum habitat for invertebrates, and a synopsis of some typical reclamation efforts designed for macroinvertebrate habitat. Refs.
Article
It was believed that the historical spawning grounds of the anadromous Chinese Sturgeon (Acipenser sinensis) were located along an about 600 km long river section reaching from the lower reaches of the Jinshajiang River to the upper reaches of the Yangtze Rive. As a result of the construction of the Gezhouba Hydroelectric Dam was built in 1981; the upstream spawning migration route was blocked by the Dam. Successful natural reproduction; however; has been observed in small areas below the dam since 1982. Some biologists held that there was a certain relationship between the spawning of Chinese sturgeon (CS) and the hydrology as well as the substrate types of the river bottom. In total; spawning runs of the CS were observed 37 times between 1983 and 2004. Five hydrological factors (water temperature; water level; flow discharge; silt content and current velocity) were monitored on a daily basis at the spawning ground between October and November for 22 years (1983 to 2004). The current velocity on the spawning ground at the river bottom was measured while CS were spawning during 4 years (1996 to 1999). The authors analyzed the relationship between five hydrological factors and the respective spawning runs. The results showed that mean current velocity during October and November and the resulting mean silt content in the sediment in November in the reach of spawning ground were significant differences (P < 0.001) from those immediately after the construction of the Gezhouba Dam. However; monthly mean water level; flow discharge and water temperature had no obvious effects on the bottom conditions. The 22-years of observations indicate that the daily mean values of all of the 5 hydrological factors fluctuated within a certain range while CS were spawning. It is concluded that the optimal values for the hydrological factors during the spawning run are 18. 0 to 20. 0°C for temperature; 14100 m3/s discharge volume; a water level of 42. 0 to 45. 0m above sea level; and a silt content in the water of 0. 2 to 0. 3 kg/m3 while the current speed above the bottom to stimulate the fish to spawn should be between 1.0 to 1. 7m/s. The optimal water temperature might provide an essential pre-condition for the other factors becoming a valid trigger for spawning. As water temperature arrive approaches the optimal values and most of the other parameters are at the brink to deviate from their optimal range values (water level; current velocity; silt content in the water); CS would begin to spawn. By 2009; when the Yangtze Three Gorges Project; which is located 45 km upstream the Gezhouba Dam; is completed and begins to operate normally; changes in the downstream water temperature are expected and these may have a negative effect on the gonad development and the stimulation of spawning of CS; however; the anticipated decline of silt content in the water may be considered as favourable for the performance of the spawning site.
Article
Densities of, and potential nesting substrates for, cavity-nesting birds were examined in a mature plains cottonwood (Populus sargentii) community in northeastern Colorado. Although snag (dead tree) densities were low (0.66/ha), the cavity-nesting guild included 7 species with densities ≤463 birds/100 ha. This finding suggests that cavity nesters are not limited by snag densities. Most (94.2%) of the nest substrate for cavity-nesting birds was provided by live trees with large, dead limbs (≥10 cm in diam). Both total dead limb length and the number of trees with dead limbs were highly correlated (P < 0.001) with the number of cavities excavated. Large trees (>55 cm in diam at breast ht [dbh]) and dead limbs 15-30 cm in diameter were preferred for cavity excavation. Because snags were a minor component of potential nest substrate, snag management may not be a useful concept for cavity-nesting birds in cottonwood bottomlands, and snag retention aspects of habitat models would be relatively unimportant for this forest type. Live-tree management is recommended.
Article
A number of analogous (convergent) adaptations occur in hole-nesting birds. Their main causes are the safe nesting sites and the keen competition (both intra- and interspecific) for them. Competition has caused certain characteristics in behavior, such as development of territorial behavior only after finding a suitable hole, fighting for a nesting-hole instead of for a territorial area, and the male's demonstration of the nesting-hole in courtship-display. The safety of the nesting site has caused other adaptations, such as frequent polygamy, hissing notes in incubating adults and in the young, lack of cryptic color in the eggs, large clutch size, and slow development of eggs and young. A long period of evolution is needed, however, before a species is able to take full advantage of the safety of the nesting site. In primary hole-nesters the adaptations are much more clearly developed than in secondary hole-nesters. Tits, for instance, have maintained spotted eggs, open-nesting Parrots white eggs. The Pied and Spotted Flycatchers have nearly identical growth curves in the young, in spite of the one having very safe and the other very unsafe nesting sites, and so on. The number of subspecies was found to show a positive correlation to clutch size (hence, hole-nesting birds tend to have larger number of subspecies). This may be due to stronger selection in species with more offspring, and/or the fact that species with large clutches are relatively often non-migratory.
Article
We used fish assemblage data collected by daytime electrofishing during 1996–1999 from 155 main-channel-border sites on 30 large warmwater rivers in Wisconsin to construct, test, and apply an index of biotic integrity (IBI). Our goal was to develop an effective and rapid way to use fishes to assess the environmental quality of river ecosystems in the state. Fourteen sites were visited more than once for a total of 187 samples, 101 of which (randomly chosen) were used to develop the IBI and the remaining 86 to test it. Prior to sampling, sites were classified as “least impacted” or as affected by impoundments, daily “peaking” flows from hydropower dams, non-point-source pollution from the watershed, point source pollution from industrial and municipal discharges (within the last 35 years), or multiple human impacts. Of the 26 potential IBI metrics considered, 10 were chosen: the total weight of the catch (excluding tolerant species); the number of native, sucker, intolerant, or riverine specialist species; the percentage of the individuals captured that were deformed or diseased, riverine specialists, or simple lithophilous spawners; and the percentage of the total weight of the catch that were insectivores or round-bodied suckers. Six metrics had different scoring criteria for northern and southern Wisconsin. For both the test subset and the entire dataset, the least-impacted sites had significantly higher mean scores and lower temporal variation than the other site classifications, indicating that they had the best ecosystem quality. Multiple-impact and non-point-source sites had the lowest means and most variable scores, signifying degraded ecosystem quality. Impoundment and hydropower peaking sites had slightly but not significantly better scores. Peaking sites on river reaches that are highly fragmented by dams tended to have lower scores than peaking sites on relatively long (>60 km), contiguous river reaches. Point source sites had significantly better scores than multiple-impact and non-point-source sites, indicating benefits to biotic integrity from recent treatment of municipal and industrial discharges.
Article
We feel that the statistical procedure employed by Keller & Melhorn (Geo Abstracts 78E/2230) is inappropriate and that consequently their conclusion is not justified by the results. Indeed, when appropriate statistical methods are used, the null hypothesis that the aluvial and bedrock streams have equal mean pool spacings is rejected at the 0.05 level. This is the opposite of their result. -from Authors
Article
Chapters are on status of riparian ecosystems in the U.S.; ecological functions and properties of riparian ecosystems to fish and wildlife; and considerations in valuation (ecologic and economic) of riparian ecosystems.-from US Govt Reports Announcements 7, 1982
Article
Provides habitat information for evaluating impacts on fish and wildlife habitat resulting from water or land use changes. Models are included that provide a numerical index of habitat suitability on a 0.0 to 1.0 scale, based on the assumption that there is a positive relationship between the index and habitat carrying capacity.-from US Govt Reports Announcements, 23, 1982
Article
The Parshall flume was developed nearly 70 years ago to measure open-channel discharge accurately for agricultural applications. When the flume is subjected to numerous wet-dry, freeze-thaw, and heating-cooling cycles, the flume becomes susceptible to settlement. As the flume settles, the measurement accuracy becomes suspect. Commercially available Parshall flumes were purchased and assembled in accordance with the manufacturer's instructions and tested in the laboratory. A series of 383 experiments was performed to determine the accuracy of the Parshall flume when subjected to an array of settlement and submergence conditions. The results indicated that although significant difference between apparent and measured discharges exists, the apparent discharge can be corrected. An analysis of the submergence test results determined that for submergence of less than 90%, the flow can be corrected to within +/- 3%. However, flow conditions with submergence of 90% or greater can only be corrected to within +/- 5%. A comprehensive procedure is presented for adjusting the apparent discharge for settlement and submergence conditions.
Article
The stream ecology of the East River is studied using benthic macro-invertebrates as indicator species. Samples were taken from 12 selected sites with different environmental conditions, from the upper reaches to the lower reaches. Four sites were selected to assess restoration strategies. The taxon richness, number density, biodiversity, and bio-community indices of benthic invertebrates remain at a relatively high level in the upper and middle reaches of the East River, but reduce to nearly zero in the lower reaches. The main ecological stresses are loss of habitat because of reclamation and the separation of riparian waters from the river. An important restoration strategy is to create multiple habitats with high habitat diversity, such as riparian lakes, wetlands, backwaters and sluggish flow zones, and to reconnect separated oxbow lakes with the river. Riparian waters should be managed in a similar way in Zengjiang Bay, allowing river flow to carry fine sediments into the riparian waters. Consequently, the fine sediment can deposit to form a mud layer. Fishes and invertebrates may live and spend parts of their life cycle in riparian waters. The Fengshuba Dam causes instantaneous fluctuation in flow discharge, and the aquatic ecology in the downstream reaches is impacted. A restoration strategy is required to adjust the operation scheme of the reservoir. Slope erosion and landslides also impact the stream ecology; the main restoration strategy for this is reforestation.
Article
Experimental research on meandering channels, carried out in a large bed of sand at Wallingford, included tests with cyclic varying discharges. Comparisons of meander length with experiments under steady conditions provide information on the “formative” or “dominant” discharge.Field data from many sources are also analysed, on the bases of mean discharge, average flow in the month of maximum flow, mean annual flood, and bank-full discharge. This tends to confirm bank-full flow as the condition which generates the characteristic meander length.
Article
Historically, assessments of water quality using periphytic communities have centered around indexes of structure such as biomass estimates, diversity indices, cluster analyses, and species abundances and distributions. However, perturbation of a community's structural attributes may not be concomitant with functional changes, and it follows that protection of community structural integrity would not signify protection of ecosystem function. A series of model streams provided semicontrolled experimental conditions for study of nontaxonomic attributes of periphytic community structure and function (photosynthesis) in response to a variety of perturbants. Over all of the model stream experiments, measured functional values were statistically less variable (P = 0.05) than measured structural values. No significant reduction in variability of structural or functional measurements was found for the treated streams relative to untreated or reference streams. A unified effort incorporating both structural and functional measurements should yield information adequate for accurate evaluation of impacts of perturbants on periphytic communities and aquatic ecosystems.
Article
The key to the river restoration approach is for the habitat biologist to have input into the process prior to a change in channel morphology brought about by modification, rather than after the habitat and population changes have already occurred. After a brief review of the basic in-stream components of fish habitat (for brevity, this will focus on the salmonid family), the impacts of various channel modification activities on habitat diversity will be discussed. The concluding section of the chapter will then concentrate on channel restoration procedures and structures to enhance fish habitat, from a planning aspect as well as from a design and installation approach. Refs.
Article
A conceptual model has been developed to test river regulation concepts by linking physical habitat and water temperature with salmonid population and production in cold water streams. Work is in progress to examine numerous questions as part of flow evaluation and habitat restoration programmes in the Trinity River of California and elsewhere. For instance, how much change in pre-smolt chinook salmon (Oncorhynchus tshawytscha) production in the Trinity River would result from a different annual instream allocation (i.e. up or down from 271 × 106 m3 released in the late 1980s) and how much change in pre-smolt production would result from a different release pattern (i.e. different from the 8.5 m3 s−1 year-round release). The conceptual model is being used to: design, integrate and improve young-of-year population data collection efforts; test hypotheses that physical habitat significantly influences movement, growth and mortality of salmonid fishes; and analyse the relative severity of limiting factors during each life stage. The conceptual model, in conjunction with previously developed tools in the Instream Flow Incremental Methodology, should provide the means to more effectively manage a fishery resource below a regulated reservoir and to provide positive feedback to planning of annual reservoir operations.
Article
Alternative ways to apply the guild concept to wildlife management are evaluated here. I reject the idea that indicator species can be selected for each bird guild to reduce costs of environmental assessment and monitoring. Promise is seen, however, in the option of using whole guilds to indicate the capability of habitat zones to support populations of wildlife species. It may be adequate for most management purposes to delineate guilds only for species that use an environment for breeding, because transients and winter residents probably use the same zones of the habitat in the same ways. Potential guilds are identified by cells of a two-dimensional matrix, the axes identifying primary feeding and nesting zones. Some questions may be answered with guilds as delineated by all cells in the matrix. Alternatively, larger guilds can be formed by grouping all species in each column or row of the matrix to identify, for example, all species that depend on tree canopies for foraging, or tree boles for nesting. One can also consider separately the resident breeders, migrant breeders, and winter residents to obtain insights into whether observed changes in numbers of birds in a guild are a result of conditions locally or elsewhere. I conclude that the guild concept probably has a place in wildlife management, but much testing must be done before it is widely applied.
Article
Aquatic habitats in a deeply incised sand-bed channel were modified by adding 1,380 t of stone and planting dormant willow posts. Restoration structures (groin extensions and longitudinal toe protection) were designed as complements to existing channel stabilization works. Prior to restoration, base-flow aquatic habitats were characterized by uniform conditions, little woody debris or riparian vegetation, shallow depths, and sandy bed material. The stage-discharge relationship, channel geometry, and bed material size were unaffected by restoration, but the average depth of scour holes adjacent to extended groins increased from 32 cm to 72 cm, and pool habitat in the lower half of the study reach increased from 2.9% to 14% of water surface area. Median water depth at base flow increased from 9 cm to 15 cm. Woody vegetation cover on one side of the channel increased from 38% to 78%. Fish numbers tripled, median fish size increased by 50%, and the number of species increased from 14 to 19. Groin extensions experienced partial failure due to erosion of sand from underneath stones.
Article
Multi-metric indices of biological integrity (IBIs) are most frequently created by examining single biological metrics along gradients of environmental degradation, and then combining multiple metrics using "best professional judgment" to characterize and calibrate stressor-response relationships. We aim to provide an efficient data analysis and visualization tool to assess the simultaneous effects of anthropogenic stressors on the fish population through the fish metrics and the associated Index of Biotic Integrity (IBI). Kohonen's self-organizing feature maps (SOM), unsupervised neural networks, are employed to pattern the sampling sites in the state of Ohio based on similar metrics characteristics. Canonical correspondence analysis (CCA) allows us then to draw conclusions about the role of the environmental variables in maintaining the perfect abode for fishes. Different visualizations superimposed with SOM clustering are realized to explore the complex interrelationships in the aquatic system and aid watershed managers to comprehend the effects of the environment on the fish.