Natural Stream Conditions Research Articles

Stream Restoration Is Influenced by Details of Engineered Habitats at a Headwater Mine Site

A lack of information regarding which ecological factors influence restoration success or failure has hindered scientifically based restoration decision-making. We focus on one headwater site to examine factors influencing divergent ecological outcomes of two post-mining stream restoration projects designed to improve instream conditions following 70 years of mining impacts. One project was designed to simulate natural stream conditions by creating a morphologically complex channel with high habitat heterogeneity (HH-reach). A second project was designed to reduce contaminants and sediment using a sand filter along a straight, armored channel, which resulted in different habitat characteristics and comparatively low habitat heterogeneity (LH-reach). Within 2 years of completion, stream habitat parameters and community composition within the HH-reach were similar to those of reference reaches. In contrast, habitat and community composition within the LH-reach differed substantially from reference reaches, even 7–8 years after project completion. We found that an interaction between low gradient and high light availability, created by the LH-reach design, facilitated a Chironomid-Nostoc mutualism. These symbionts dominated the epilithic surface of rocks and there was little habitat for tailed frog larvae, bioavailable macroinvertebrates, and fish. After controlling for habitat quantity, potential colonizing species’ traits, and biogeographic factors, we found that habitat characteristics combined to facilitate different ecological outcomes, whereas time since treatment implementation was less influential. We demonstrate that stream communities can respond quickly to restoration of physical characteristics and increased heterogeneity, but “details matter” because interactions between the habitats we create and between the species that occupy them can be complex, unpredictable, and can influence restoration effectiveness.

Local effects of deforestation on stream fish assemblages in the amazon-savannah transitional area

Abstract The expansion of agriculture in the southeast Amazon-Savanah transitional area has greatly decreased forest cover and influenced stream structure and functioning. We assessed the effects of forest cover loss on the integrity of streams by assessing stream physical conditions and the taxonomic and functional diversity of fish assemblages in this transitional area. We hypothesize that low forest cover, especially adjacent to streams, results in poor physical conditions (e.g., warmer temperatures, less physical structure, etc.), which in turn will decrease the taxonomic and functional diversity of fish assemblages. We detected that loss of forest cover negatively affects natural stream conditions and reduces the functional diversity of fish assemblages, but we did not find a strong effect on taxonomic diversity. Ambush and stalking predators, diurnal surface pickers (groups that exhibit opportunistic life history strategies), grazers, pickers, and browsers (groups that exhibit equilibrium life history strategies) were the functional groups with the strongest relation to altered environments. These groups can explore different niches, both with natural characteristics or altered by human activities. Our results suggest that the preservation of riparian zones can minimize the loss of specialized fish species in assemblages of Amazon-Savannah stream systems.

Behavioural response of sea lamprey (Petromyzon marinus) to acoustic stimuli in a small stream

Sea lamprey (Petromyzon marinus) are invasive in the Laurentian Great Lakes and parasitically feed on valued fishes. Migration barriers and selective pesticides are used to control sea lamprey, but there is a desire to develop additional control tools such as traps with nonphysical deterrents. Sound has been used as a deterrent for other invasive species, but its potential for manipulating sea lamprey behavior in natural stream conditions remains untested. Here, behavioral responses of upstream-migrating adult sea lamprey in response to low frequency sounds of 70 or 90 Hz was tracked in a small stream (8 m wide) using passive integrated transponder (PIT) telemetry. The low frequency sounds shifted sea lamprey distribution, with up to 30% more sea lamprey detected on PIT antennas without sound compared with PIT antennas with sound playing. Future studies could continue testing low frequency sounds in larger rivers with larger speakers for use as a natural deterrent at sea lamprey barriers to push sea lamprey toward traps.

Spatial and temporal variations of the diatom communities in megacity streams and its implications for biological monitoring.

Diatoms have been proven to be good indicators of natural stream conditions, but little is known about the seasonal variability of diatom communities in megacity streams. We investigated the spatial and temporal variation of diatom communities along an urban-to-rural gradient in megacity streams, Beijing, China. We found that the composition and diversity of diatom community was significantly different along the urban-to-rural gradient in streams of Beijing city. The diatom community was subtle temporal variation in the reference stream and urban upstream, but the temporal variation of diatoms was relatively greater in the urban downstream. Overall, the composition of the diatom community was relatively stable in the streams among different seasons, and the dominant species did not change much over seasons. For example, during the sampling periods, the species Achnanthidium minutissimum in reference streams had the average relative abundance of 20.3 ± 3.5%; the species Pseudostaurosira brevistriata and Staurosira construens var. venter in urban upstream had average relative abundances of 17.0% ± 0.9% and 17.3% ± 1.2%, respectively; and the species Nitzschia palea in urban downstream had average relative abundances of 18.8 ± 4.7%. There were significant correlations between the relative abundances of the dominant species and environmental variables, suggesting that the environmental variables had significant effects on the diatom distribution. Our results demonstrate that the diatom communities are relatively stable among seasons in different sampling areas, suggesting that diatoms can be used as reliable indicators for the biological monitoring of water quality in megacity streams across seasons.

An integrative conservation planning framework for aquatic landscapes fragmented by road-stream crossings

Road-stream crossings represent a significant source of habitat fragmentation for global aquatic ecosystems, yet integrative conservation planning frameworks are lacking for most regions. We describe a connectivity conservation planning framework that draws on recent advances in the fields of surveying, modelling, and optimizing removal of crossings that block aquatic organism passage. We demonstrate this framework with a case study involving 1200 crossings surveyed in Florida, USA in which barrier severity was quantified on a continuous scale from 0 (complete barrier) to 1 (no barrier). Using field surveys, we built a boosted regression tree (BRT) model that linked barrier severity to 44 landscape variables representing natural (e.g., stream size) and anthropogenic (e.g., land use) stream conditions. We used a recently developed optimization routine to conduct two scenarios, including (1) surveyed crossings only and (2) surveyed crossings plus crossings modelled at 5545 unsurveyed locations. The BRT model explained 54% of variation in barrier severity scores and showed that the most severe barriers occurred on small, high-elevation streams draining urban and agricultural catchments. Estimates of connectivity gains following remediation were 5.3-times lower when unsurveyed locations were included in the optimization, suggesting inclusion of unsurveyed sites is critical for conservation planning. Results from this framework can be used over short (e.g., planning immediate barrier mitigation) and long (e.g., planning future field surveys) time horizons to benefit aquatic connectivity conservation. The survey protocol and modelling methods used here, combined with global datasets on stream conditions, can be applied to benefit connectivity planning in other regions.

Characterisation of natural streams using community indices and basal resources of macroinvertebrates in the upper Euphrates Basin

The characterisation of natural stream conditions is the first important step to analyse ecological quality of streams in the Euphrates basin. We found that the community indices correspond to very good ecological conditions in five natural streams of that region. The macroinvertebrates composition differed significantly between September and May. Number of taxa and Shannon index were significantly higher in autumn than in spring. FPOM and biofilm were the most relevant basal resources of benthic invertebrates.

Hydrodynamics of storage release during river ice breakup

The breakup of the ice cover in cold-region rivers is a brief but seminal period of their hydrologic regime, with important ecological and socio-economic implications. The main driver of ice breakup processes is the flow discharge hydrograph. It is generated by runoff from snowmelt and rainfall but can be modified by rapid release of water from storage as the ice cover recedes by ablation and mechanical breaking up. Despite its potential importance, there is very limited quantitative information concerning the hydrodynamic processes that control storage release during ice breakup in rivers, while the issue of climate change underscores the need for improved understanding of the relevant mechanisms. Quantitative analysis for assumed prismatic channels shows that ablation and sustained ice dislodgment and breaking can cause significant flow enhancement via storage release. The latter process is far more dynamic than ablation and, under certain conditions, may lead to formation of a self-sustaining wave (SSW). Analytical results are applied to natural stream conditions, using the Lower Peace River as a case study. Observed rates of ice recession typically indicate ice melt as the dominant process. A rare occurrence of rapid ice breaking over hundreds of kilometres (2014) indicated partial agreement with the SSW concept and revealed that discrepancies may arise from the characteristic irregularity of rivers. Impacts on storage release by climate-driven changes to river ice regimes are examined, along with their implications to ice-jam formation and associated flooding.

Modelling and experimental study of coupled exchange ofp,p′-DDE and colloids in a flume simulated stream-streambed system

Stream–subsurface exchange plays a significant role in the fate and transport of contaminants in streams. It has been modelled explicitly by considering fundamental processes such as hydraulic exchange, colloid filtration, and contaminant interactions with streambed sediments and colloids. The models have been successfully applied to simulate the transport of inorganic metals and nutrients. In this study, laboratory experiments were conducted in a recirculating flume to investigate the exchange of a hydrophobic organic contaminant, p,p′-dichloro-diphenyl-dichloroethane (DDE), between a stream and a quartz sand bed. A previously developed process-based multiphase exchange model was modified by accounting for the p,p′-DDE kinetic adsorption to and desorption from the bed sediments/colloids and was applied to interpret the experimental results. Model input parameters were obtained by conducting independent small-scale batch experiments. Results indicate that the immobilization of p,p′-DDE in the quartz sand bed can occur under representative natural stream conditions. The observed p,p′-DDE exchange was successfully simulated by the process-based model. The model sensitivity analysis results show that the exchange of p,p′-DDE can be sensitive to either the sediment sorption/desorption parameters or colloidal parameters depending on the experimental conditions tested. For the experimental conditions employed here, the effect of colloids on contaminant transport is expected to be minimal, and the stream–subsurface exchange of p,p′-DDE is dominated by the interaction of p,p′-DDE with bed sediment. The work presented here contributes to a better mechanistic understanding of the complex transport process that hydrophobic organic contaminants undergo in natural streams and to the development of reliable, predictive models for the assessment of impacted streams. Copyright © 2015 John Wiley & Sons, Ltd.

Mobility of lowland stream Trichoptera under experimental habitat and flow conditions

The species-specific mobility of six species of lowland stream Trichoptera was studied in flume experiments with different habitats and current flows. The test species were selected according to their occurrence along the environmental gradient from more natural towards highly disturbed sandy, lowland streams of the North-West European plain. Two groups of species were distinguished, three species occurring more frequently towards the natural end versus three occurring more frequently towards the disturbed end of the stream disturbance gradient. Experiments were conducted in a temperature and light controlled environment in indoor, re-circulating, man-made stream channels with four replicate gutters each. The bottom of each gutter held ten trays filled with five selected habitat materials (two trays each), which provided refugia and food. Three flow treatments with constant current velocities of 10, 30, or 50 cm/s were applied. Movements were scored based on visual observations of the position of each individual at fixed time points. The first day after release, individuals moved around very actively; this ‘release effect’ was removed from further analyses. The trichopteran species occurring near the more natural end of the disturbance gradient exhibited significantly less mobility (on average 10–15% of individuals actively moved around) than the species from the more disturbed end of the gradient (on average 30–40% of individuals actively moved around). The first group of trichopteran species also spent significantly longer times in the leaves habitat compared to the other three species, which moved more or less independent of habitat. With increasing current velocity, all test species moved more frequently, particularly the species from the more disturbed end of the gradient. This could indicate behavior to avoid dislodgement. The mobility of all species exceeded the mobility needed to use habitat resources of food and shelter, both present in excess. Therefore, short-term movement could also be (partly) a random behavior. Overall, the more tolerant species from the disturbed end of the gradient showed more mobility and flexibility than the species occurring under more or less natural stream conditions. This was consistent with the hypothesis that mobility is an adaptation of tolerant, ubiquitous species. Mobility is an adaptation of r-strategists.

Leaf litter from insect‐resistant transgenic trees causes changes in aquatic insect community composition

Summary1. Recent research has addressed how transgenic residues from arable crops may influence adjacent waterways, aquatic consumers and important ecosystem processes such as litter breakdown rates. With future applications of transgenic plants in forestry, such concerns may apply to forest stream ecosystems. Before any large‐scale release of genetically modified (GM) trees, it is therefore imperative to evaluate the effects of genetic modifications in trees on such ecosystems.2. We conducted decomposition experiments under natural stream conditions using leaf litter from greenhouse grown GM trees (Populus tremula × Populus tremuloides) that express Bacillus thuringiensis (Bt) toxins (cry3Aa; targeting coleopteran leaf‐feeding beetles) to examine the hypothesis that GM trees would affect litter decomposition rates and/or the aquatic arthropod community that colonizes and feeds on leaf litter in streams.3. We show that two independent transformations of isogenic Populus trees to express Bt toxins caused similar changes to the composition of aquatic insects colonizing the leaf litter, ultimately manifested in a 25% and 33% increases in average insect abundance.4. Measurements of 24 phenolic compounds as well as nitrogen (N) and carbon (C) in the litter did not significantly differ among modified and wild‐type trees and were thus not sufficient to explain these differences in the insect assemblage.5. Decomposition rates were comparable among litter treatments suggesting that the normal suite of leaf traits influencing decomposition was similar among litter treatments and that the shredding functions of the community were maintained despite the changes in insect community composition.6. Synthesis and applications. We report that leaf litter from GM trees affected the composition of aquatic insect communities that colonized litter under natural stream conditions. This suggests that forest management using GM trees may affect adjacent waterways in unanticipated ways, which should be considered in future commercial applications of GM trees. We also argue that studies at different scales (e.g. species, communities and ecosystems) will be needed for a full understanding of the environmental effects of Bt plants.

Stabilization of fine gravels by net‐spinning caddisfly larvae

AbstractWe examined the impact of Hydropsychidae caddisfly larvae on the incipient motion of two sizes of narrowly graded fine‐gravel (4–6 and 6–8 mm). This impact was assessed relative to the collective impact of other abiotic and biotic processes that are potentially important conditioning agents of fine‐gravels. Trays of gravel were placed in the River Soar, Leicestershire, UK, where they were colonized to natural densities by caddisfly larvae. Identical trays that were surrounded by a 250 µm mesh were also deployed, preventing colonization but allowing field conditioning of sediments, including minor reworking of grains and biofilm development. After 21 days in the river, trays were removed to a laboratory flume where grain entrainment stresses were established. In addition to the colonized and conditioned treatments, critical shear stresses were measured for identical sediments that were not placed in the river (laboratory gravels). Gravels that were colonized by Hydropsychidae required significantly greater shear stresses for entrainment than conditioned trays (p ≤ 0·002), however, there was no significant difference between conditioned and laboratory gravels. This implies that the presence of caddisfly can be a more important influence on fine‐gravel stability than some conditioning processes. Shields parameter was compared across treatments and across the two gravel size‐fractions using two‐way ANOVA. No significant differences or interactions were observed, indicating that 4–6 mm gravel was stabilized to a similar degree as 6–8 mm gravel by conditioning and colonization processes. Our results extend earlier studies in two important ways: (1) entrainment stresses were established for fine gravels that were colonized at natural densities, under natural stream conditions; and (2) the caddisfly effect was measured relative to both field‐conditioned and unconditioned laboratory controls. The temporal and spatial distribution of silk‐spinning caddisfly larvae suggests that they have the potential to influence fine‐sediment mobility in many rivers, worldwide. Copyright © 2008 John Wiley & Sons, Ltd.

Genetic implications of translocation and stocking of fish species, with particular reference to Western Australia

Species or strains of fish may be translocated for farming, where the only access to the wild is via inadvertent escapes, or for stocking, where deliberate releases are undertaken. In either case, it is important that the translocated animals are representative of the donor population(s) in terms of genetic composition and level of variability. Many studies have shown that this ideal is difficult to achieve, the major reason being the use of inadequate numbers or composition of broodstock as founders of a strain. Also, where more than one conspecific population is involved, there may be outbreeding depression problems. In the case of farming, measures to improve the introduced strain genetically are likely to be undertaken, e.g. breeding programmes, manipulation of sex and ploidy, transgenic techniques. Such approaches are necessary economically, but can alter genetic make-up. Thus, stringent attempts must be made to minimize escapes or reduce their impact should they occur. With stocking, genetic change during captive rearing should be avoided. No strain manipulation should be undertaken, and other agents of change should be minimized. Stocking may result in hybridization with related species or with endemic populations of the same species. In either case, there can be detrimental genetic effects on the native forms. To be able to identify subsequently any genetic changes in reared strains, whether intended for farming or stocking, wild population composition should be determined, using appropriate molecular techniques. Such molecular methods will demonstrate the degree of interpopulation differentiation and, thus, reproductive isolation. The same markers should then be used in each subsequent generation (in the hatchery and after escape or reintroduction to the wild) to monitor any changes in genetic composition or variability. Markers should include microsatellite DNA loci, but the inclusion of more than one type of marker is recommended. However, as the aforementioned markers are not considered to be influenced by natural selection, they give no information on the adaptive nature of such differences. For this reason, it is suggested that markers influenced by selection should be investigated. Monitoring a strain subsequent to deliberate or inadvertent release can be undertaken using genetic markers, either deliberately enhanced by breeding or occurring naturally. Highly variable minisatellite DNA loci have been used as family markers in farmed escape studies with Atlantic salmon. These investigations have demonstrated significantly superior survival of native strains compared with farmed salmon in natural stream conditions. These latter results, demonstrating fitness differences, were strongly indicative of local adaptation. Thus, methods exist to monitor the genetic effects of translocation and stocking. However, a holistic approach should be taken to such exercises, where genetics forms part of a wider suite of considerations.

Delayed Egg Hatching and Semivoltinism in the Nearctic Stonefly Megarcys signata (Plecoptera: Perlodidae)

Delayed egg hatching can influence the survival of aquatic insects by reducing exposure to competitors, predators, parasites, or unfavorable environmental conditions. We examined egg development in a Colorado population of the stonefly, Megarcys signata (Plecoptera: Perlodidae), whose larvae inhabit high altitude streams in the Rocky Mountains of western North America. Five-thousand fertilized eggs were collected from 40 different females and incubated in the East River, Gunnison County, Colorado, until late fall, at which time unhatched eggs were transported to incubation chambers in Ithaca, New York. We used three different combinations of photoperiod and temperature (10L:14D, 4°C; 10L:14D, 8°C; 8L:16D, 8°C) in an attempt to induce hatching. Eggs in the treatments with temperatures elevated above normal winter temperatures in the East River (8°C) began developing after 6 months, whereas eggs in the treatment most closely simulating natural stream conditions (4°C) did not hatch after 10 months of incubation. Our data indicate that this population of Megarcys signata has an extended egg stage that persists for almost a year, and that it is semivoltine at these elevations of 2885 and 2895 meters.

Numerical computation of river ice jams

A numerical model called RIVJAM has been developed to compute the configuration of and water levels caused by ice jams of the "wide" kind, under natural stream conditions and regardless of whether the jam has attained its full potential, known as equilibrium. Account of seepage flow through the voids of the jam enables predictions of grounding conditions to be made, in accord with observations. The model is applied to three case studies of ice jam events and found to perform satisfactorily. The various model coefficients fall within the expected ranges, with the exception of a parameter characterizing the intensity of seepage flow. More field data are needed to elucidate this matter. Key words: grounding, ice, jam, model, numerical, river, seepage, thickness, toe, wide.

Laboratory Evaluation of the Fungus Culicinomyces clavosporus for Control of Blackfly (Diptera: Simuliidae) Larvae

Comparative bioassay experiments based on 4-day exposure of mid-ins tar test larvae to conidia showed that the original isolates of the Australian and U. S. strains of Culicinomyces s clavosporus were less active against the blackflies Simulium pictipes and Simulium vittatum (with LC50s ranging from 1.9 ×104 to 1.1 × 105 conidia per ml) than against the mosquito Aedes aegypti (with LC50s between 2.1 × 102 and 3.9 × 103 conidia per ml). The activity of the “Knight” isolate of the U.S. strain was within the same range as the other isolates when assayed against A. aegypti, but it was even less active than the others when assayed against S. vittatum. To simulate natural stream conditions, larvae of S. vittatum were exposed to the Australian strain for shorter time intervals in troughs of running water. Concentrations of 2.9 × 105 to 8.3 × 105 conidia per ml for 1- and 24-h exposure times produced 90 to 100% mortality of test larvae after a 7-day holding period, whereas a 15-min exposure to 8.0 × 105 to 1.1 × 106 conidia per ml resulted in 65 to 70% mortality of test larvae after 7 days. On the basis of these results, it appears that the existing isolates of Culicinomyces are not sufficiently active against simuliid larvae to merit serious consideration as potential blackfly control agents.

Oblique Ripples on Permian Point Bars in North-Central Texas: Helical Flow or Boundary Effect?: ABSTRACT

Fine-grained point-bar deposits are well-exposed both in cross section and in exhumed epsilon cross-beds. Above a basal lag of intrabasinal caliche and mudstone clasts, the epsilon cross-beds consist of cross-laminated very fine sand grading laterally and upward into mud. The epsilon cross-beds dip from 10 to 25°, are up to 2.5 m high and 15 m wide, and show a meander radius of curvature of 45 to 500 m, as measured on aerial photographs. Sandstones in the epsilon sets are almost invariably structured into straight to slightly sinuous-crested ripples which are oriented obliquely, from 25 to 50°, to the main channel axis as inferred from the strike of the epsilon surface. The obliquity of these ripples greatly exceeds that of basal fluid flow related to a helical cell based on theory as well as observations of both experimental and natural stream conditions. An earlier study of the Muddy River, Wyoming, explained oblique bed forms by variation in boundary shear-stress. The steep transverse slopes, probably resulting from the fine-grained sediment load of the Permian rivers, are associated with increasing downstream sediment transport and ripple migration rates at progressively lower levels on the point bar. Thus bed-form orientation in this situation may reflect boundary conditions rather than the local flow directions. End_of_Article - Last_Page 923------------

The Reactions of Dominant Trout to Changes in Overhead Artificial Cover

Abstract A submerged tank at the Sagehen Creek Project of the University of California provides a facility for analysis of trout behavior under natural stream conditions. Here, studies were made to learn to what extent dominant trout will use shade provided by overhead artificial surface cover. Three overhead artificial surface covers of different size were constructed of 3/4-inch plywood. They were mounted on steel legs and painted black on the side in contact with the surface water. During each of three studies, these covers were permuted every two or three days with three different positions in the test area. Three dominant trout representative of the three common trout, brook, rainbow, and brown, were used in three separate tests. Several brook trout and rainbow trout occupied the test area simultaneously with each dominant trout. From 286 hours of observation it was learned that the rainbow trout showed the lowest use of shade produced by the overhead covers and the highest activity in movements from...

Solubility of Atmospheric Oxygen in Water: Twenty-Ninth Progress Report of the Committee on Sanitary Engineering Research of the Sanitary Engineering Division

Group of researchers in England conducted experiments that showed significant differences from previously accepted saturation concentrations of gaseous oxygen dissolved in distilled water; based on these observations, paper derives true saturation values throughout normal range of natural stream water temperatures; table lists values which are considered most satisfactory for application to natural stream conditions.

A Program for the Management of Fish Resources in Great Smoky Mountains National Park

Ideal natural stream conditions exist over the greater part of Great Smoky Mountains National Park, and carefully planned management measures are in operation. Fishes taken for sport and food are the eastern brook trout, rainbow trout, smallmouth black bass and rock bass. Rainbow trout are used to fill the gap between the waters capable of supporting eastern brook trout and those in which smallmouth bass are native. Native species are stocked in virgin waters, in research areas, and in streams where rainbow trout are not well established. A modern trout hatchery, operated by the U. S. Bureau of Fisheries, and thirty-five concrete rearing pools make up the physical plant. More rearing pools are planned. All stocking has been done in the fall, but later at least part of the fish may be planted in the spring prior to the opening of the fishing season. The prohibition of natural baits insures the preservation of native stream organisms and prevents the introduction of undesirable exotic species. A creel census on representative watersheds promises to give accurate information on the yield of the streams.