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Journal articles on the topic 'Riffle-pool structure'

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Published: 4 June 2021

Last updated: 3 February 2022

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CHIBANA, Takeyoshi. "CHARACTERISTICS OF RIFFLE-POOL STRUCTURE FORMED BY A DROP STRUCTURE." Doboku Gakkai Ronbunshuu B 66, no. 3 (2010): 223–34. http://dx.doi.org/10.2208/jscejb.66.223.

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Li, Like, Niannian Fan, and Xingnian Liu. "Experimental study on flow structure in riffle-pool channels." IOP Conference Series: Earth and Environmental Science 199 (December 19, 2018): 052055. http://dx.doi.org/10.1088/1755-1315/199/5/052055.

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TERAMOTO, Atsuko, and Tetsuro TSUJIMOTO. "RELATIONSHIP BETWEEN CHARACTERISTICS OF BAR MORPHOLOGY AND RIFFLE-POOL STRUCTURE." PROCEEDINGS OF HYDRAULIC ENGINEERING 50 (2006): 961–66. http://dx.doi.org/10.2208/prohe.50.961.

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Najafabadi, Elham Fazel, Hossein Afzalimehr, and Pawel M. Rowiński. "Flow structure through a fluvial pool-riffle sequence – Case study." Journal of Hydro-environment Research 19 (March 2018): 1–15. http://dx.doi.org/10.1016/j.jher.2018.01.001.

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Milner, Victoria S., Nigel J. Willby, David J. Gilvear, and Charles Perfect. "Linkages between reach-scale physical habitat and invertebrate assemblages in upland streams." Marine and Freshwater Research 66, no. 5 (2015): 438. http://dx.doi.org/10.1071/mf14008.

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Determining the influence of physical habitat on biological structure in minimally disturbed settings is important if the effects of alterations to physical habitat are to be understood. This study tested whether reach-scale differences in physical habitat influence macroinvertebrate community composition at 24 sites in the Cairngorm Mountains, Scotland. Stream reaches were classified into channel types based on a geomorphic typology (i.e. step-pool, bedrock, plane-bed and pool-riffle). PERMANOVA indicated an overall significant relationship between the geomorphic typology and macroinvertebrate species-level composition, and among all combinations of channel types (such as step-pool and pool-riffle, step-pool and bedrock). Most channel types were dominated by high abundances of Baetis rhodani, Rhithrogena semicolorata and Leuctra inermis, which are ubiquitous in unpolluted gravel-bedded Scottish streams. However, reflecting significant differences in abundance of commoner taxa between types, indicator value (IndVal) analysis revealed that pool-riffle reaches were characterised by elmids (Limnius sp. and Oulimnius sp.) and Caenis rivulorum, and step-pool reaches by Alainites muticus, B. rhodani, L. inermis and Brachyptera risi. Geomorphic typing of rivers provides a useful basis for the initial assessment of ecological status whereas abundance-based biological data processed at the appropriate taxonomic resolution should be sensitive to physical-habitat modifications.

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Webb, P. W. "Use of fine-scale current refuges by fishes in a temperate warm-water stream." Canadian Journal of Zoology 84, no. 8 (2006): 1071–78. http://dx.doi.org/10.1139/z06-094.

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Laboratory studies suggest that fishes are capable of using fine-scale structures to avoid swimming. Similar structures occur as dips, ripples, and eroded areas behind protruding rocky materials, within the riffle–run–pool–margin structure of streams. It is not known if laboratory-determined capabilities are used to avoid swimming in the field. I measured current speeds for in-stream structures from coarse-scale riffle–run–pool–margin to fine-scale substratum ripples and determined fish locations in these structural features during the day and night. During the day, most fishes were seen in pools, margins, and runs, which is consistent with indirect responses to predation. At night, fishes from runs and ripples moved to the lowest current speeds, including those provided by fine-scale structures in the bottom of runs and riffles with dimensions comparable to minima used in laboratory settings.

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Ferreira, Vitor Manuel Barros, João Luiz DE Caíres Souza, and Maíra Moraes. "Community structure of benthic macroinvertebrates in different types of habitat in a stream stretch of the Atlantic Rainforest." Research, Society and Development 9, no. 1 (2020): e149911848. http://dx.doi.org/10.33448/rsd-v9i1.1848.

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The benthic macroinvertebrates are organisms of extremely importance to the energy flow of lotic ecosystems, acting as a link between basal resourcers and predators. This study aimed to analyze patterns of abundance, richness and diversity of a benthic macroinvertebrates community in different types of substrate and different velocities of water. The study was carried on in a stretch of 40 meters of a headwater stream located at the Tijuca National Park, the Tijuca River. The sampling was perfomed in September 2016. We sampled four types of samples, which we denominated as “habitats”: litter in riffle, litter in pool, sand in riffle and sand in pool. A total total of 2.208 individuals were collected, with most of them being immature insects. We confirmed our assumptions by finding difference between the composition of the four types of habitats. It was found higher abundance, richness and diversity in litter habitats, confirming that the characteristics of this type of substrate are more favorable for the majority of the benthic macrofauna.

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Gu, Jung-Eun, Sang Hwa Jung, Joongu Kang, and Hyoseop Woo. "Analysis for Underwater Sound on Natural River Habitat." E3S Web of Conferences 40 (2018): 02047. http://dx.doi.org/10.1051/e3sconf/20184002047.

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A riffle-pool structure is a representative physical structure of bed in rivers. The change in the physical parameter of the habitat could lead to changes in the sound environment of rivers, which are expressed by underwater acoustics. This change in underwater sound affects fish habitat. In this study, the changes of underwater acoustics were analyzed according to the change of pool-riffle sequence in a natural river. And the correlation between underwater acoustics and hydraulic characteristics was investigated. The survey for underwater acoustics was performed in the Namdae stream where is in Gangwon province. This stream belongs to the Han River basin and the river length is 39.01 km and the catchment area is 127.56 km2. The Namdae stream is a river that accounts for more than 70% of salmon returning to South Korea. The spawning salmon will return to this area around November after growing in the Bering Sea. It is important to manage the fish habitat in this river so there is a lot of research on the enhancement of fish habitat. Hydraulic characteristics were changed by the river bed structure. In this study, we investigated the relationship between underwater acoustic characteristics and hydraulic factors such as riverbed material, flow rate and water depth of each habitat type at 12 sites. The characteristics of underwater acoustic differed relative to different hydraulic factors of the two habitats, which is riffle and pool. The sound pressure level of riffles was relatively higher than that of the pools due to bed materials, shallow depth and high water velocity of riffles. In the future, it is considered that the underwater sound can be utilized as a parameter to evaluate the physical habitat environment of the river.

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Rot, Byron W., Robert J. Naiman, and Robert E. Bilby. "Stream channel configuration, landform, and riparian forest structure in the Cascade Mountains, Washington." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 4 (2000): 699–707. http://dx.doi.org/10.1139/f00-002.

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The hierarchical relationship of five key elements, valley constraint, riparian landform, riparian plant community, channel type, and channel configuration, are described for 21 sites in mature to old-growth riparian forests of the western Cascades Mountains, Washington, U.S.A. Channel type (bedrock, plane-bed, and forced pool-riffle) was closely related to channel configuration (especially large woody debris (LWD) volume, density, and LWD-formed pools) at the smallest spatial scale and valley constraint at the largest. Valley constraint significantly influenced off-channel habitat (r2 = 0.71) and LWD volume within forced pool-riffle channels (r2 = 0.58). Riparian plant community composition was differentiated by four landform classes: three alluvial landforms based on height above the channel and one based on hillslope. Just above the active channel, floodplain landforms contained more deciduous stems than conifer and greater conifer basal area than deciduous. Conifers dominated other landforms. The diameter of in-channel LWD increased with the age of the riparian forest (r2 = 0.34). In old-growth forests, LWD diameter was equivalent to or greater than the average riparian tree diameter for all sites. In younger forests, the mixed relationship between LWD and riparian tree diameter may reflect a combination of LWD input from the previous old-growth stand and LWD input from the existing stand.

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Langeani, Francisco, Lilian Casatti, Helena Seixas Gameiro, André Bellucco do Carmo, and Denise de Cerqueira Rossa-Feres. "Riffle and pool fish communities in a large stream of southeastern Brazil." Neotropical Ichthyology 3, no. 2 (2005): 305–11. http://dx.doi.org/10.1590/s1679-62252005000200009.

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The structure of the fish communities of a pool and a rapid in the ribeirão Santa Bárbara is described. This stream of 5th order is a direct tributary of the rio Tietê in the system of the upper rio Paraná. Thirty three species, from nine families and three orders, were referred in the two mesohabitats: the pool with 31 species, and the rapid with 18. Orders Characiformes, Siluriformes, and Perciformes presented the greatest number of species in the two mesohabitats. The families Characidae and Loricariidae were the most specious, followed by Cichlidae in the pool, and by Parodontidae in the rapid. Most species were accidental, 17 in the pool, and 10 in the rapid, and only six were constant in the two mesohabitats. The greatest diversity and evenness occurred in the pool. The seasonal variation for both assemblages was high, with the pool having a high turnover of species that could be due to the proximity with main channel of the rio Tietê.

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Silveira, M. P., D. F. Buss, J. L. Nessimian, and D. F. Baptista. "Spatial and temporal distribution of benthic macroinvertebrates in a Southeastern Brazilian river." Brazilian Journal of Biology 66, no. 2b (2006): 623–32. http://dx.doi.org/10.1590/s1519-69842006000400006.

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Benthic macroinvertebrate assemblages are structured according to physical and chemical parameters that define microhabitats, including food supply, shelter to escape predators, and other biological parameters that influence reproductive success. The aim of this study is to investigate spatial and temporal distribution of macroinvertebrate assemblages at the Macaé river basin, in Rio de Janeiro state, Southeastern Brazil. According to the "Habitat Assessment Field Data Sheet - High Gradient Streams" (Barbour et al., 1999), the five sampling sites are considered as a reference condition. Despite the differences in hydrological parameters (mean width, depth and discharge) among sites, the physicochemical parameters and functional feeding groups' general structure were similar, except for the less impacted area, which showed more shredders. According to the Detrended Correspondence Analysis based on substrates, there is a clear distinction between pool and riffle assemblages. In fact, the riffle litter substrate had higher taxa in terms of richness and abundance, but the pool litter substrate had the greatest number of exclusive taxa. A Cluster Analysis based on sampling sites data showed that temporal variation was the main factor in structuring macroinvertebrate assemblages in the studied habitats.

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Rosenfeld, Jordan. "Effects of fish predation in erosional and depositional habitats in a temperate stream." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 7 (2000): 1369–79. http://dx.doi.org/10.1139/f00-073.

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Combined effects of predation by benthic and drift-foraging fish (prickly sculpin (Cottus asper) and coho salmon (Onchorhynchus kisutch) parr) on benthic invertebrate community and trophic structure were evaluated in Mayfly Creek, a previously fishless stream in the Coast Range Mountains of British Columbia. The role of microhabitat (substrate) in mediating predation effects was assessed by comparing invertebrate community structure on unglazed ceramic tiles and gravel baskets nested within enclosures. The role of macrohabitat was evaluated by placing enclosures in pool and riffle habitats. Effects of fish predation were most pronounced on tile substrate and in riffle habitat and least pronounced on gravel substrate in pool habitat. The presence of fish caused a decrease in abundance of larger-bodied herbivores (primarily the mayflies Ameletus and Baetis) and had positive indirect effects on algae and smaller invertebrates (primarily Orthocladiinae chironomids and nemourid stoneflies), probably through competitive release. In contrast with herbivores, detritivorous invertebrates were less influenced by fish predation and more highly correlated with the abundance of organic detritus. The distribution and abundance of detritivores in Mayfly Creek appear to be primarily influenced by bottom-up forces (implying resource limitation), while grazers in algal-based food chains are more strongly influenced by top-down effects (fish predation).

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Rosa, BFJV, RT Martins, and RG Alves. "Distribution of oligochaetes in a stream in the Atlantic Forest in southeastern Brazil." Brazilian Journal of Biology 75, no. 1 (2015): 1–7. http://dx.doi.org/10.1590/1519-6984.02313.

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The oligochaetes are considered good indicators of ecological conditions and specific types of habitats. Among the factors that influence the distribution of these invertebrates are the water flow and the nature of the substrate. The aim of this study is to describe the composition and distribution of oligochaete species in a first-order stream in Atlantic Forest and try to identify if some species are associated with characteristics of particular types of habitats. In the dry season and in the rainy season, sand and litter samples in two riffle areas and two pool areas were collected in different parts along the stream using a hand net. The greatest observed richness and abundance occurred in sand in the pool, however the greatest estimated richness was obtained for litter in the pool. The Kruskal-Wallis analysis showed effect of the different types of habitat on the abundance and richness of oligochaetes. The Nonmetric Multidimensional Scaling (NMDS) and Multiresponse Permutation Procedure analysis (MRPP) indicated that the variation in the fauna composition had relation with different types of substrates. The indicator species analysis showed that Limnodrilus. hoffmeisteri was an indicator species in both the riffle sand and pool sand and Pristina americana was only an indicator in the pool sand. The high organic matter content in both sandy habitats probably favored the greater abundance of oligochaetes. The results showed that the substrate constitutes an important factor for the local distribution of these invertebrates in streams. The variation of the community structure among mesohabitats and the presence of indicator species of specific types of habitats in the stream demonstrate the importance of environmental heterogeneity for the oligochaetes fauna in forested streams.

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Komulaynen, Sergey. "Structure and Dynamics of Algal Communities in Small River of the Republic of Karelia (Rusia)." Botanica 24, no. 1 (2018): 59–68. http://dx.doi.org/10.2478/botlit-2018-0006.

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AbstractDistribution of phytoplankton, phytoperiphyton and microphytobenthos communities was simultaneously studied in the River Lihzma (Republic of Karelia, Russia). Comparison includes both taxonomic and quantitative parameters along river continuum. Special attention was given to the analysis of causes of spatial inhomogeneity of algal communities. In the studied river, the pattern and trends of dynamics in the community were dependent on high current velocities and the alternation of lake, pool, and riffle zones. Algae are constantly removed from bottom biotopes, attached forms are detached from their substrate and are transported by the stream, and planktonic forms settle down, disturbing the distinctive characteristics of communities and resulting in the formation of “mixed” communities.

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Schwartz, John S., Keil J. Neff, Frank E. Dworak, and Robert R. Woockman. "Restoring riffle-pool structure in an incised, straightened urban stream channel using an ecohydraulic modeling approach." Ecological Engineering 78 (May 2015): 112–26. http://dx.doi.org/10.1016/j.ecoleng.2014.06.002.

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Rosenfeld, Jordan S. "Modelling the effects of habitat on self-thinning, energy equivalence, and optimal habitat structure for juvenile trout." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 9 (2014): 1395–406. http://dx.doi.org/10.1139/cjfas-2013-0603.

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Self-thinning theory predicts that decline in density with increasing individual mass should match the exponent of the metabolism–body mass relationship (∼0.9 in salmonids). However, self-thinning assumes energy equivalence (constant energy available to a cohort as it ages), which may be unrealistic for mobile taxa. I evaluate this assumption using a bioenergetic–stream habitat model to assess the sensitivity of available energy and self-thinning slopes to changes in habitat structure (percent pool). Self-thinning slopes across three age-classes of juvenile trout (young of the year, 1+, and 2+) were sensitive to both modelled habitat structure and density-independent mortality rates. Density-independent overwinter mortality generated self-thinning curves similar to those expected from metabolic allometry, even without habitat limitation (density-dependent mortality). Energy available to sympatric cohorts was unequal under most habitat configurations because of size-based differences in swimming performance that affected habitat availability and interference competition (dominance) that allowed resource monopolization by older cohorts. The optimal habitat structure that maximized abundance of the 2+ age-class (and best approximated energy equivalence) was ∼40% pool, but this value was sensitive to density-independent mortality rate and assumptions about the effect of the pool to riffle ratio on invertebrate prey production.

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Caamaño, D., P. Goodwin, and J. M. Buffington. "Flow structure through pool-riffle sequences and a conceptual model for their sustainability in gravel-bed rivers." River Research and Applications 28, no. 3 (2010): 377–89. http://dx.doi.org/10.1002/rra.1463.

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Wu, Chia-Yu, and Joann Mossa. "Decadal-Scale Variations of Thalweg Morphology and Riffle–Pool Sequences in Response to Flow Regulation in the Lowermost Mississippi River." Water 11, no. 6 (2019): 1175. http://dx.doi.org/10.3390/w11061175.

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The lowermost Mississippi River (LMR) is one of the largest deltaic systems in North America and one of the heavily human-manipulated fluvial river systems. Historic hydrographic surveys from the mid-1900s to the early 2010s were used to document the thalweg morphology adjustments, as well as the riffle–pool sequences. Extensive aggradation was observed during 1950s to 1960s, as the Atchafalaya River was enlarging before the completion of the Old River Control Structure (ORCS). Following the completion of the ORCS, reductions in sediment input to the LMR resulted in net degradation of the thalweg profile patterns since the mid-1960s except for the 1992–2004 period. Different flood events that supplied sediment might be the cause of upstream aggradation from 1963–1975 and net aggradation along the entire reach from 1992–2004. Furthermore, the change pattern of thalweg profiles appear to be controlled by backwater effects, as well as the Bonnet Carré spillway opening. Results from riffle–pool sequences reveal that the averaging Ws ratios (length to channel width) are 6–7, similar to numerous previous studies. Temporal variations of the same riffles and pools reveal that aggradation and degradation might be heavily controlled by similar factors to the thalweg variations (i.e., sediment supply, backwater effects). In sum, this study examines decadal-scale geomorphic responses in a low-lying large river system subject to different human interventions, as well as natural flood events. Future management strategies of this and similar river systems should consider recent riverbed changes in dredging, sediment management, and river engineering.

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Montgomery, David R., Eric M. Beamer, George R. Pess, and Thomas P. Quinn. "Channel type and salmonid spawning distribution and abundance." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 3 (1999): 377–87. http://dx.doi.org/10.1139/f98-181.

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Consideration of fundamental channel processes, together with map-based and field investigations, indicates that stream channel type influences salmonid spawning distributions across entire channel networks and salmonid abundance within channel reaches. Our analysis suggests that salmonid spawning patterns in mountain drainage basins of the Pacific Northwest are adapted to, among other things, the timing and depth of channel bed mobility. We hypothesize that because the bed of pool-riffle and plane-bed reaches scours to a variable fraction of the thickness of alluvium, survival to emergence is favored by either burying eggs below the annual scour depth or avoiding egg burial during times of likely bed mobility. Conversely, annual mobility of all available spawning gravel in steeper step-pool and cascade channels favors either adaptations that avoid egg burial during times of likely bed mobility or selection of protected microhabitats. Consistent with these expectations, we find that salmonid spawning distributions track channel slope distributions in several west-slope Pacific Northwest watersheds, implying that spatial differences in channel processes influence community structure in these rainfall-dominated drainage basins. More detailed field surveys confirm that different channel types host differential use by spawning salmonids and reveal finer-scale influences of pool spacing on salmonid abundance.

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Hodge, Rebecca A., David A. Sear, and Julian Leyland. "Spatial variations in surface sediment structure in riffle-pool sequences: a preliminary test of the Differential Sediment Entrainment Hypothesis (DSEH)." Earth Surface Processes and Landforms 38, no. 5 (2012): 449–65. http://dx.doi.org/10.1002/esp.3290.

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TASHIRO, Takashi, and Tetsuro TSUJIMOTO. "DISCUSSION ON CHANGE IN RIFFLE-POOL STRUCTURE BY USING FREQUENCY OF DISTURBANCE ON RIVER-BED AS A HABITAT SUITABILITY INDEX." PROCEEDINGS OF HYDRAULIC ENGINEERING 46 (2002): 1151–56. http://dx.doi.org/10.2208/prohe.46.1151.

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Brown, Larry R., and Anne M. Brasher. "Effect of predation by Sacramento squawfish (Ptychocheilus grandis) on habitat choice of California roach (Lavinia symmetricus) and rainbow trout (Oncorhynchus mykiss) in artificial streams." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 8 (1995): 1639–46. http://dx.doi.org/10.1139/f95-758.

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We studied the effects of predatory Sacramento squawfish (Ptychocheilus grandis) on habitat choice of juvenile California roach (Lavinia symmetricus), adult roach, and juvenile rainbow trout (Oncorhynchus mykiss) in artificial streams. In single-prey trials, the proportion of fish found in pool habitat declined in the presence of squawfish for juvenile roach (from 0.55 to 0.00), adult roach (from 0.88 to 0.13), and juvenile rainbow trout (0.70 to 0.15). The presence of squawfish did not affect the use of riffle and edge habitats. Of the fish found in shallow water, the proportion found in edge habitat declined from juvenile roach (0.95) to adult roach (0.80) to juvenile rainbow trout (0.23). We also conducted experiments designed to simulate invasion of an area by squawfish, in which adult roach and juvenile rainbow trout were tested together in the presence and absence of squawfish. The proportion of prey in pool habitat in the presence of squawfish was greater in the two-prey trials than in the single-prey trials for both adult roach (0.31 and 0.13, respectively) and juvenile rainbow trout (0.33 and 0.15, respectively). These results support field evidence that squawfish are an important force in determining the spatial structure of native stream fish assemblages.

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Endreny, T. A., and M. M. Soulman. "Hydraulic analysis of river training cross-vanes as part of post-restoration monitoring." Hydrology and Earth System Sciences 15, no. 7 (2011): 2119–26. http://dx.doi.org/10.5194/hess-15-2119-2011.

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Abstract. River restoration design methods are incrementally improved by studying and learning from monitoring data in previous projects. In this paper we report post-restoration monitoring data and simulation analysis for a Natural Channel Design (NCD) restoration project along 1600 m of the Batavia Kill (14 km2 watershed) in the Catskill Mountains, NY. The restoration project was completed in 2002 with goals to reduce bank erosion and determine the efficacy of NCD approaches for restoring headwater streams in the Catskill Mountains, NY. The NCD approach used a reference-reach to determine channel form, empirical relations between the project site and reference site bankfull dimensions to size channel geometry, and hydraulic and sediment computations based on a bankfull (1.3 yr return interval) discharge to test channel capacity and sediment stability. The NCD project included 12 cross-vanes and 48 j-hook vanes as river training structures along 19 meander bends to protect against bank erosion and maintain scour pools for fish habitat. Monitoring data collected from 2002 to 2004 were used to identify aggradation of pools in meander bends and below some structures. Aggradation in pools was attributed to the meandering riffle-pool channel trending toward step-pool morphology and cross-vane arms not concentrating flow in the center of the channel. The aggradation subsequently caused flow splitting and 4 partial point bar avulsions during a spring 2005 flood with a 25-yr return interval. Processing the pre-flood monitoring data with hydraulic analysis software provided clues the reach was unstable and preventative maintenance was needed. River restoration and monitoring teams should be trained in robust hydraulic analytical methods that help them extend project restoration goals and structure stability.

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Crisci-Bispo, Vera L., Pitágoras C. Bispo, and Claudio G. Froehlich. "Ephemeroptera, Plecoptera and Trichoptera assemblages in litter in a mountain stream of the Atlantic Rainforest from Southeastern Brazil." Revista Brasileira de Zoologia 24, no. 3 (2007): 545–51. http://dx.doi.org/10.1590/s0101-81752007000300004.

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The study of Ephemeroptera, Plecoptera and Trichoptera associated with litter in southeastern Brazil streams aimed to answer the following questions: 1) Does richness and composition of EPT fauna differ between riffle and pool mesohabitats despite being associated to the same substratum, litter? 2) Does the similarity of the EPT fauna between both mesohabitats change with time? 3) Does the EPT functional feeding structure differ between both mesohabitats (riffles-pools)? In order to answer these questions, monthly collections, from November 1999 to June 2000, were done in Ribeirão (Stream) Bocaina with a D-net (10 litter patches in riffles and 10 in pools). The EPT fauna at Ribeirão Bocaina was more diversified and more abundant in the litter in riffles than in the litter in pools, although, when richness was standardized for the same number of individuals it became similar in both conditions. EPT fauna was very different between both mesohabitats in terms of faunal composition as well as in terms of function. Probably it was due to differences in water speed, in the time of litter residence and in the concentration of dissolved oxygen between both mesohabitats.

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Kasahara, Tamao, Thibault Datry, Michael Mutz, and Andrew J. Boulton. "Treating causes not symptoms: restoration of surface - groundwater interactions in rivers." Marine and Freshwater Research 60, no. 9 (2009): 976. http://dx.doi.org/10.1071/mf09047.

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Many river restoration projects seek to address issues associated with impaired hydrological and ecological connectivity in longitudinal (e.g. effects of dams, weirs) or lateral (e.g. alienated floodplain) dimensions. Efforts to restore the vertical dimension of impaired stream–groundwater exchange are rare, hampered by limited understanding of the factors controlling this linkage in natural alluvial rivers. We propose a simplified two-axis model of the ‘primary drivers’ (sediment structure and vertical hydraulic gradient) of stream–groundwater exchange that acknowledges their interaction and provides a practical template to help researchers and river managers pose hypothesis-driven solutions to restoration of damaged or lost vertical connectivity. Many human activities impact on one or both of these drivers, and we review some of the tools available for treating the causes (rather than symptoms) in impacted stream reaches. For example, creating riffle-pool sequences along stream reaches will enhance vertical hydraulic gradient, whereas flushing flows can remove clogging layers and sustain sediment permeability. Our model is a first step to specifying mechanisms for recovery of lost vertical connectivity. Assessing results of river restoration using this approach at reach to catchment scales will provide scientific insights into the interplay of hydrology, fluvial geomorphology and river ecosystem function at appropriately broad scales.

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Martin–Smith, Keith M., Lindsay M. Laird, Luke Bullough, and Matthew G. Lewis. "Mechanisms of maintenance of tropical freshwater fish communities in the face of disturbance." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 354, no. 1391 (1999): 1803–10. http://dx.doi.org/10.1098/rstb.1999.0522.

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Community resistance to, and resilience from, perturbation will determine the trajectory of recovery from disturbance. Although selective timber extraction is considered a severe disturbance, fish communities from headwater streams around Danum Valley Field Centre, Sabah, Malaysia, showed few long–term changes in species composition or abundance. However, some species showed short–term (< 18 months) absence or decrease in abundance. These observations suggested that both resistance and resilience were important in maintaining long–term fish community structure. Resistance to perturbation was tested by monitoring fish communities before and after the creation of log–debris dams, while resilience was investigated by following the time–course of recolonization following complete removal of all fish. High community resistance was generally shown although the response was site–specific, dependent on the composition of the starting community, the size of the stream and physical habitat changes. High resilience was demonstrated in all recolonization experiments with strong correlations between pre– and post–defaunation communities, although there was a significant difference between pool and riffle habitats in the time–course of recovery. These differences can be explained by the movement characteristics of the species found in the different habitats. Resilience appeared to be a more predictable characteristic of the community than resistance and the implications of this for ensuring the long–term persistence of fish in the area are discussed.

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Fazel Najafabadi, Elham, Hossein Afzalimehr, and Jueyi Sui. "A comparison of two-dimensional and three-dimensional flow structures over artificial pool-riffle sequences." Canadian Journal of Civil Engineering 44, no. 12 (2017): 1084–98. http://dx.doi.org/10.1139/cjce-2017-0274.

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Experiments have been carried out in a flume with one 2D pool-riffle sequence and one 3D pool-riffle sequence, respectively. Objectives of this study are to determine whether or not the convergence of lateral flow exists. Variations of the near-bed shear stress have been studied. The characteristics of the secondary currents along a pool-riffle sequence have been investigated. Results showed that for the 3D pool-riffle sequence, the near-bed velocity decreases along convective deceleration flow (CDF) and increases along convective acceleration flow (CAF), respectively. It is found that the shear velocities estimated from the slope of the velocity gradient in the inner layer, decrease in the CDF section, and increase in the CAF section in the 3D pool-riffle sequences. The Reynolds shear stress is highest at the CDF section along longitudinal lines with distances of 10 cm and 20 cm away from the channel wall.

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Serna M., Daniel José, Cesar Enrique Tamaris-Turizo, and Luis Carlos Gutiérrez Moreno. "Spatial and temporal distribution of Trichoptera (Insecta) larvae in the Manzanares river Sierra Nevada of Santa Marta (Colombia)." Revista de Biología Tropical 63, no. 2 (2015): 465. http://dx.doi.org/10.15517/rbt.v63i2.15604.

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The aquatic insects are important bioindicators of water quality in rivers and streams. The order Trichoptera is part of this group, plays an important role in aquatic systems and because of the multiple functions they fulfill, it is essential to know about their biodiversity. This study aimed to know the Trichoptera composition, and its spatial and temporal distribution, in close relationship with the available microhabitats, and some physical and chemical variables, in the middle and lower sections of the Manzanares river basin (Sierra Nevada of Santa Marta, Colombia). A total of eight microhabitats were sampled in three sites from August 2002 to February 2003, and during the rainy and dry seasons. A total sample of 3 316 Trichoptera larvae were collected, belonging to 10 family and 14 genera; six of these genera and one family are new records for the Magdalena department. The caddisflies presented the greatest abundance and richness on leaves in pool, leave in riffles and stones in riffle, where Nectopsyche (28%), Leptonema (17%) and Smicridea (15%) were the more predominant genus. Structure and composition of Trichoptera genus in each site changed in function to the rainfall pattern, and physical and chemical variables presented in the basin, showing the lowest abundance and richness during high rainfall period (October and November), and the greatest abundance and richness in low rainfall period (December, January and February). Likewise, stations with higher values of dissolved oxygen and lower in temperature and conductivity reported the greatest abundance of Trichoptera. The Trichoptera showed affinity to the specific microhabitats, variations in their composition in relationship whit climatic periods and pollution levels of the river. To know others aspects about the Trichoptera distribution, we recommended continuing these studies including annual cycles and increasing the altitudinal gradients.

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Turyahabwe, Remigio, Andrew Mulabbi, Joyfred Asaba, and Moses Olowo. "Ecological Responses of Macroinvertebrates to an In-Stream Ecosystem Restoration Technique in a Tropical Stream in Eastern Uganda." East African Journal of Environment and Natural Resources 3, no. 1 (2021): 129–44. http://dx.doi.org/10.37284/eajenr.3.1.398.

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A field experiment was conducted to examine the ecological responses of macroinvertebrates to an in-stream ecosystem restoration technique called woody debris introduced in a stream in different arrangements to show how they (woody debris) affected the macroinvertebrate ecology, specifically assemblage composition and biometrics in River Nabongo. The experiment was carried out in two heterogeneous stream environments i.e., i) in a riffle found in the middle reaches of the river at a higher altitude and ii) a pool in the lower altitude and reaches of the river. Each of these two treatments had a control plot for comparison purposes. Four macroinvertebrate sampling campaigns were launched in experimental sites from September 2019 to April 2021. All restoration structures had more macroinvertebrates than control and pre-treatment sites. The introduction of simple structures at the riffle site led to an increase in collector-filterers from 9-128 individuals, while at the pool site all the structures increased macroinvertebrates by 1151 individuals. Taxon richness was highest in the complex plot with 14±0.41 which significantly differed from the rest of the sampling plots at P<0.05. The relative abundance of taxa at the pool site varied significantly from one sampling plot to another at P<0.05 with the highest mean abundance registered in complex and simple structures having 61.3±0.10 and 23.5±0.11 respectively. It was concluded that complex woody debris structures increase the diversity, abundance and richness of aquatic macroinvertebrates by providing hard substrates for colonization by algae and microorganisms on which macroinvertebrates feed. We recommended that other researchers should study the impact of other in-stream ecosystem restoration techniques such as floating islands, constructed wetlands, D-deflectors, a comparison of which with restored woody debris will enable ecologists to choose the most suitable technique to apply at different stream points.

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Harrison, Megan L., Trent M. Hoover, and John S. Richardson. "Agonistic behaviours and movement in the signal crayfish, Pacifastacus leniusculus: can dominance interactions influence crayfish size-class distributions in streams?" Canadian Journal of Zoology 84, no. 10 (2006): 1495–504. http://dx.doi.org/10.1139/z06-141.

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Size-structured population distributions can result from stage-specific differences in habitat preference or from intraspecific dominance interactions between large and small individuals. The relative importance of these two factors in structuring population distributions was examined in the signal crayfish ( Pacifastacus leniusculus (Dana, 1852)), an organism whose populations are distinctly spatially size-sorted in streams, with adults (A) occupying deeper pools and juveniles (J) inhabiting riffles. In the first of two experiments, groups of crayfish (2A, 2A+2J, or 4J) were released in a constructed riffle–pool–riffle sequence in an experimental channel and individual behaviours and rates of movement were recorded at 2 min intervals. There were differences in habitat preference between the two size classes: adults showed a distinct preference for pools, whereas juveniles did not. In the second experiment, pairs of individuals (A+A, A+J, J+J) were placed in experimental arenas. Analysis of recorded interactions between pairs showed that agonistic interactions and subsequent post-encounter movements were sufficient to produce the exclusion of subordinate individuals from habitats occupied by dominant individuals. These results show that adults have a greater preference for pool habitats than juveniles and that interactions between asymmetrically sized pairs are likely to displace smaller individuals from areas where adult–juvenile encounter rates are high.

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Dashtpeyma, Hamed, and Bruce MacVicar. "Vortex-Resistance Hypothesis: Large Eddy Simulation of Turbulent Flow in Isolated Pool- Riffle Units." E3S Web of Conferences 40 (2018): 05029. http://dx.doi.org/10.1051/e3sconf/20184005029.

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By numerical simulations of turbulent flow in isolated poolriffle units with various riffle heights, four different types of vortices were found and named as follows: surface rollers (SR), corner rollers (CR), ramp rollers (CR), and axial tails (AT). Surface rollers are shaped on the flow surface due to submerged hydraulic jump or any obstacles in the forced poolriffle units. Corner rollers are shaped close to the corners near the walls at the pool head. Ramp rollers are formed at the bed of the channel on the ramp into the head of the pool. All kinds of vortices stretch in the streamwise direction as they travel to the downstream, which they are called axial tails. The simulations showed that all four types of vortices interact with each other, combine, amplify or cancel out each other as they travel downstream. The strength of vortices and how they interact result into different types of flow patterns. The surface rollers combine with corner rollers to make a jet like plunging flow near the pool bed. In other cases with lower riffle heights, ramp rollers tend to push the flow up, which in turn leads to higher turbulence near the bed and higher velocity near the flow surface (skimming flow). Moreover, if both surface rollers and ramp rollers have the similar strength (e.g., vorticity) and scale, the streamwise velocity profile has a peak around the middle of the flow, and minimum velocities near the bed and free surface. This flow pattern was named as “rifting flow.” Based on these findings, a new hypothesis is proposed called ‘vortex-resistance,’ which states that the turbulent structures, by increasing the eddy viscosity and changing the pressure domain, act as an obstacle that steers the flow. Plunging and skimming flow can thus be understood as the products of different types of turbulent structures. These findings provide new clarifications to long-standing questions related to the hydraulics of pools and riffles.

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Najafabadi, Elham Fazel, and Hossein Afzalimehr. "Comparison of Two- and Three-Dimensional Flow and Habitat Modeling in Pool–Riffle Sequences." Iranian Journal of Science and Technology, Transactions of Civil Engineering 44, no. 3 (2019): 991–1000. http://dx.doi.org/10.1007/s40996-019-00298-4.

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Booker, D. J., D. A. Sear, and A. J. Payne. "Modelling three-dimensional flow structures and patterns of boundary shear stress in a natural pool-riffle sequence." Earth Surface Processes and Landforms 26, no. 5 (2001): 553–76. http://dx.doi.org/10.1002/esp.210.

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Ibrahim, Ahmad, Peter Steffler, and Yuntong She. "Estimating the Hyporheic Depth Beneath a Pool-Riffle Bedform Using the Rankine Body Analytical Method." Journal of Hydrologic Engineering 25, no. 8 (2020): 04020034. http://dx.doi.org/10.1061/(asce)he.1943-5584.0001944.

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Carré, David M., Pascale M. Biron, and Susan J. Gaskin. "Flow dynamics and bedload sediment transport around paired deflectors for fish habitat enhancement: a field study in the Nicolet River." Canadian Journal of Civil Engineering 34, no. 6 (2007): 761–69. http://dx.doi.org/10.1139/l06-083.

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Schemes to restore fish habitat in rivers often involve installing instream structures such as current deflectors to create and maintain riffle-pool sequences. However, there is a lack of field studies on the impact of these structures on flow dynamics and bed topography. The objective of this research is to characterize flow dynamics and sediment transport around paired deflectors used to enhance fish habitat in the Nicolet River, Quebec. Bed and bank topography surveys were taken with a total station, and velocity and bed shear stress estimates were obtained from an acoustic doppler velocimeter. Bedload sediment transport was assessed by two methods: tracer rocks (painted "particles" and passive integrated transponder tags) and sediment traps. Results show marked differences in bedload sediment transport patterns between the left bank and the right bank downstream of the deflectors. This is surprising considering that paired deflectors should produce a relatively symmetrical disruption to the flow field on each side. More high-flow dynamics data during overtopping conditions are required to understand the complex interactions between these instream structures and bedload transport. Key words: stream restoration, pool, bedload transport, radio frequency identification (RFID), passive integrated transponder (PIT) tags, fieldwork, deflectors, fish habitat.

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Schwartz, John S., and Edwin E. Herricks. "Evaluation of pool-riffle naturalization structures on habitat complexity and the fish community in an urban Illinois stream." River Research and Applications 23, no. 4 (2007): 451–66. http://dx.doi.org/10.1002/rra.986.

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Whiteway, Sarah L., Pascale M. Biron, André Zimmermann, Oscar Venter, and James W. A. Grant. "Do in-stream restoration structures enhance salmonid abundance? A meta-analysis." Canadian Journal of Fisheries and Aquatic Sciences 67, no. 5 (2010): 831–41. http://dx.doi.org/10.1139/f10-021.

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Despite the widespread use of stream restoration structures to improve fish habitat, few quantitative studies have evaluated their effectiveness. This study uses a meta-analysis approach to test the effectiveness of five types of in-stream restoration structures (weirs, deflectors, cover structures, boulder placement, and large woody debris) on both salmonid abundance and physical habitat characteristics. Compilation of data from 211 stream restoration projects showed a significant increase in pool area, average depth, large woody debris, and percent cover, as well as a decrease in riffle area, following the installation of in-stream structures. There was also a significant increase in salmonid density (mean effect size of 0.51, or 167%) and biomass (mean effect size of 0.48, or 162%) following the installation of structures. Large differences were observed between species, with rainbow trout ( Oncorhynchus mykiss ) showing the largest increases in density and biomass. This compilation highlights the potential of in-stream structures to create better habitat for and increase the abundance of salmonids, but the scarcity of long-term monitoring of the effectiveness of in-stream structures is problematic.

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Cui, Yantao, John K. Wooster, Jeremy G. Venditti, Scott R. Dusterhoff, William E. Dietrich, and Leonard S. Sklar. "Simulating Sediment Transport in a Flume with Forced Pool-Riffle Morphology: Examinations of Two One-Dimensional Numerical Models." Journal of Hydraulic Engineering 134, no. 7 (2008): 892–904. http://dx.doi.org/10.1061/(asce)0733-9429(2008)134:7(892).

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Pires, Mateus Marques, Ana Emília Siegloch, Malva Isabel Medina Hernández, and Maurício Mello Petrucio. "Environmental drivers and composition of assemblages of immature odonates (Insecta) in a subtropical island in southern Brazil." Acta Limnologica Brasiliensia 32 (2020). http://dx.doi.org/10.1590/s2179-975x8017.

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Abstract: Aim Describe the diversity of immature stages of Odonata (Insecta) in streams from a subtropical island in southern Brazil and investigate the influence of environmental variables on the composition of their assemblages. Methods Eleven low-order streams (1st to 3rd order) were sampled in two conservation units located in the island of Santa Catarina (southern Brazil) between 2010 and 2012. Immature specimens of Odonata were collected using a Surber sampler. The influence of water abiotic parameters and habitat structure (mesohabitats: riffle vs. pool areas, microhabitats: litter vs. stone substrates) on the composition of Odonata was tested through the seasons using ordination diagrams and redundancy analysis. Results Nine odonate genera from seven families were recorded in the study region. The genera Desmogomphus, Epigomphus (Gomphidae), Heteragrion (Heteragrionidae) and Perilestes (Perilestidae) have their first records described for the state of Santa Catarina. Additionally, biological notes are provided for other odonate genera concerning substrate use. The composition of Odonata communities changed over the seasons and they were influenced by water temperature and velocity. Additionally, odonate composition differed significantly between microhabitats (substrate type) and mesohabitats (riffle vs. pool areas) in the streams studied. Conclusions The lower genera richness of Odonata recorded in the island of Santa Catarina in relation to other Brazilian subtropical streams is probably associated with the insular condition of the study region. This study also demonstrated that substrate (organic and inorganic) and mesohabitat (riffle and pool) types were important drivers of the composition of the fauna of immature odonates, evidencing the role of climate and habitat structure in influencing subtropical stream insect communities.

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MacVicar, B. J., and A. G. Roy. "Hydrodynamics of a forced riffle pool in a gravel bed river: 2. Scale and structure of coherent turbulent events." Water Resources Research 43, no. 12 (2007). http://dx.doi.org/10.1029/2006wr005274.

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Nika, Nerijus, Tomas Virbickas, and Antanas Kontautas. "Spawning site selection and redd gravel characteristics of sea trout Salmo trutta in the lowland streams of Lithuania." Oceanological and Hydrobiological Studies 40, no. 1 (2011). http://dx.doi.org/10.2478/s13545-011-0006-7.

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AbstractTo date, no characterization of spawning habitats on scientific basis was made for the eastern Baltic salmonid populations. The aim of the present study was to characterize spawning habitat preferences and redd gravel structure of sea trout in lowland streams of western Lithuania. The redd position at the habitat-unit scale, microhabitat hydrological characteristics and the redd gravel structure have been analyzed. The spawning site selection by sea trout was related to the in-stream characteristics, but not to the riparian features. Redds were positioned mainly in the transitional pool-riffle zones, associated with close proximity to potential cover for spawners. At the microhabitat scale, sites with relatively consistent hydrological parameters (mode of water depth 0.25–0.40 m, flow velocity 0.4–0.7 m s−1 and Froude number 0.2–0.4) were selected from a wide range of available sites. Egg incubation conditions, in terms of the redd gravel structure in the spring, were of intermediate quality, while varied widely within particular reaches. According to the results of the present study, it is apparent that sea trout have particular preferences for spawning sites, which should be considered in emerging river-restoration projects.

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Lehotský, Milan, Zuzana Pastuchová, Eva Bulánková, and Igor Kokavec. "Testing for longitudinal zonation of macroinvertebrate fauna along a small upland headwater stream in two seasons." Biologia 71, no. 5 (2016). http://dx.doi.org/10.1515/biolog-2016-0065.

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AbstractThe effect of longitudinal zonation patterns and macroinvertebrate responses to changes in habitat characteristics have been given a lot of attention. But studies of changes in macroinvertebrate assemblages along small upland undisturbed watercourses are still lacking. The aim of the study is to analyse variability in macroinvertebrate communities between two different habitats/morphological sequences – shallow (riffle/run/step/) and deeper (pool) channel-bed morphological units on the background of the environmental parameters (local relief, slope, channel confinement ratio, channel-valley walls connectivity, floodplain continuity and channel abut, channel sinuosity and predominant land cover of riparian zone) of seven valley segments (functional process zones) in two seasons of the year (spring and autumn). The longitudinal-downstream gradient research was conducted on the semi-natural upland headwater brook in the Little Carpathians (9,330 m long, average gradient 2.8%) at 15 morphological sequences (30 sampling points). Each sampling point in spring as well as in autumn was characterised by mean flow velocity, discharge, water depth, channel width, channel bottom particle size, and flow types. Selected physico-chemical variables: pH, dissolved oxygen content (DO), oxygen saturation (DO %), temperature (t) conductivity and total dissolved solids (TDS) were measured directly in the field using the multisonde measuring device. Organisms were identified into the family level. The results showed that differences in zonation of benthic invertebrates between seasons are more apparent than seasonal variability between pools and riffles. Spring samples followed the increasing gradient of total dissolved solids downstream with characteristic families for upper and lower stretch. The disruption of macroinvertebrates zonation was more evident in autumn samples with greatest effects in pools. Based on RDA, the distribution of families was driven by three significant variables in riffles and four in pools. Alike environmental factors of pool sequences in the middle and upper reaches were responsible for similarity in macroinvertebrate structure. In conclusion, the distribution pattern of benthic invertebrates of the natural part of the small headwater stream in terms of abundance of macroinvertebrate families followed the longitudinal zonation in spring, but in autumn were the local habitat conditions more important.

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Magoulick, Daniel D., Matthew P. Dekar, Shawn W. Hodges, Mandy K. Scott, Michael R. Rabalais, and Christopher M. Bare. "Hydrologic variation influences stream fish assemblage dynamics through flow regime and drought." Scientific Reports 11, no. 1 (2021). http://dx.doi.org/10.1038/s41598-021-89632-3.

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AbstractHydrologic variation can play a major role in structuring stream fish assemblages and relationships between hydrology and biology are likely to be influenced by flow regime. We hypothesized that more variable flow regimes would have lower and more variable species richness, higher species turnover and lower assemblage stability, and greater abiotic environment-fish relationships than more stable flow regimes. We sampled habitats (pool, run, and riffle) in three Runoff/Intermittent Flashy streams (highly variable flow regime) and three Groundwater Flashy streams (less variable flow regime) seasonally (spring, early summer, summer and autumn) in 2002 (drought year) and 2003 (wet year). We used backpack electrofishing and three-pass removal techniques to estimate fish species richness, abundance and density. Fish species richness and abundance remained relatively stable within streams and across seasons, but densities changed substantially as a result of decreased habitat volume. Mixed model analysis showed weak response variable-habitat relationships with strong season effects in 2002, and stronger habitat relationships and no season effect in 2003, and flow regime was not important in structuring these relationships. Seasonal fish species turnover was significantly greater in 2002 than 2003, but did not differ between flow regimes. Fish assemblage stability was significantly lower in Runoff/Intermittent Flashy than Groundwater Flashy streams in 2002, but did not differ between flow regimes in 2003. Redundancy analysis showed fish species densities were well separated by flow regime in both years. Periodic and opportunistic species were characteristic of Runoff/Intermittent Flashy streams, whereas mainly equilibrium species were characteristic of Groundwater Flashy streams. We found that spatial and temporal variation in hydrology had a strong influence on fish assemblage dynamics in Ozark streams with lower assemblage stability and greater fluctuations in density in more hydrologically variable streams and years. Understanding relationships between fish assemblage structure and hydrologic variation is vital for conservation of fish biodiversity. Future work should consider addressing how alteration of hydrologic variation will affect biotic assemblages.

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Calderon, Martha S., and Kwang-Guk An. "An influence of mesohabitat structures (pool, riffle, and run) and land-use pattern on the index of biological integrity in the Geum River watershed." Journal of Ecology and Environment 40, no. 1 (2016). http://dx.doi.org/10.1186/s41610-016-0018-8.

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