HYDRAULIC PREFERENCES OF SHRIMPS AND FISHES IN TROPICAL INSULAR RIVERS

Hydraulic habitat models based on the preferences of species for the hydraulic characteristics of their microhabitats are frequently used to evaluate the impact on the habitat of a change in river flow regime. Their application in a tropical insular environment is still limited as little is known about the hydraulic preferences of species. Hydraulic preference models have been developed for 15 taxa (diadromous shrimps and fishes) sampled in 52 rivers in the Caribbean (the French West Indies) and the Indian Ocean (the Reunion island). Five datasets were used and group 8353 samples collected by electrofishing during 320 surveys (reach × date) performed between 1999 and 2011. Generalized additive models were used to link variations of taxa density within surveys to the hydraulic characteristics of the microhabitat (velocity, depth and substrate). Hydraulic preferences within each region (Caribbean and Indian Ocean) are significant for most of the taxa and vary little between rivers and surveys. The hydraulic variables explain up to 18.1% (univariate models) and 30.0% (multivariate models) of the deviance of densities within survey. Of the taxa selected, Atya scabra, Macrobrachium heterochirus, Xiphocaris elongata and the Sicydiinae are the most demanding. Copyright © 2013 John Wiley & Sons, Ltd.     

Past hydraulics influence microhabitat selection by invertebrates and fish in hydropeaking rivers

Hydropeaking hydropower plants are the main source of renewable energy, meeting sub-daily peaks in electricity demand. They induce rapid artificial flow variations, highly variable velocities, drift, and stranding risks for aquatic organisms. In hydropeaking reaches, microhabitat selection likely depends on both present and past hydraulics (flow velocity and water depth); this study aims to assess their relative impact. For this purpose, we used observations of fish abundance in 1,180 microhabitats (507 sampled by electrofishing, 673 by snorkeling) and of invertebrate abundance in 36 microhabitats (hyporheic and benthic) in a medium-sized hydropeaking river. We described past hydraulics of microhabitats over the 15 days preceding sampling, using a 2D hydrodynamic model, by identifying microhabitats dewatering (drying during >10 hr) or with high-velocity conditions (>1.3 m s⁻¹ during >10 hr). Invertebrates guilds (defined based on their selection of present hydraulics in rivers without hydropeaking) responded significantly to past hydraulics, with abundances 3.5–15.3 times lower in dewatering habitats. Selection for present hydraulics by invertebrates was different from that observed in rivers without hydropeaking. For more mobile fish, responses were weaker and different, with a “bank” guild selecting dewatering microhabitats and, secondarily, a “midstream” guild avoiding them. Selection of present hydraulics by fish was similar to that observed in rivers without hydropeaking. Overall, past hydraulics influenced microhabitat selection, with stronger effects on invertebrates and stronger effects of dewatering than of high past velocities. However, high past velocities force fish to move and invertebrates to experience a large range of velocity.     

Fish assemblages and stream hydraulics: consistent relations across spatial scales and regions

General relationships between organisms and their habitat, consistent across spatial scales and regions, suggest the existence of repeatable ecological processes and are useful for the management of stream networks. From published data, we defined four guilds of European fish species with contrasting preferences for microhabitat hydraulics within stream reaches. At the scale of stream reaches and across 139 French sites (590 460 fishes sampled), we analysed how fish guild proportions were related to reach hydraulics (proportion of pools vs. riffles %POOL; median discharge by unit width Q50/W). The strongest correlations were observed between two fish guilds and %POOL (p < 0.001, r² ≥ 0.41) and between one fish guild proportion and Q50/W (p < 0.001, r² = 0.10). These reach–scale relationships were consistent across six large French basins, and consistent with the analyses made at the microhabitat scale. Therefore, microhabitat preferences for hydraulics are strong enough to generate consistent reach‐scale community responses to hydraulics across regions, despite the influence of other filters such as temperature, nutrient levels or history. The distribution of basic geomorphic features (pools, riffles) in streams and their modification (by dams, weirs and dikes) can modify the proportion of fish guilds by up to 80%, probably contributing to the long‐term decline of riffle‐dwelling species in Europe. Copyright © 2006 John Wiley & Sons, Ltd.     

INFLUENCE OF THE MORPHOLOGICAL AND HYDRAULIC CHARACTERISTICS OF MOUNTAIN STREAMS ON FISH HABITAT SUITABILITY CURVES

Microhabitat preferences of adult brown trout (Salmo trutta m. fario) were monitored for the purpose of determining design parameters for river restoration. The habitat preferences were evaluated during the summer period of minimum flows. Since 1995, field measurements have been performed in 52 reaches in 43 mountain and piedmont streams. The relationship between hydraulic characteristics and the values of maximum habitat suitability derived from velocity and depth habitat suitability curves (HSCs) was statistically determined. Trout in natural stream reaches showed a strong degree of dependence on depths, but in regulated streams, they were dependent on velocities. The representative habitat suitability curves for four depth intervals were extrapolated. From these outputs, the optimum depths of a microhabitat for river restoration measures and/or assessment of the influence of water withdrawals can be derived. The influence of geological regions on the shape of HSCs has not been proved; therefore, it is conceivable that after verification, the generalized HSCs may also be valid in other mountain and piedmont regions. Copyright © 2011 John Wiley & Sons, Ltd.     

The generality of abundance‐environment relationships in microhabitats: A comment on Lancaster and Downes (2009)

We comment on a criticism of hydraulic preference models and instream habitat models. We provide evidence of the generality of many hydraulic preference models, which supports their use in instream habitat modelling even if the detailed mechanistic causes of the observed preferences are not fully known. We also reply to the assertion that preference models are not based on sound ecological theory. We identify unbalanced use of available knowledge and point out limitations relating to too detailed biological focusses. Copyright © 2010 John Wiley & Sons, Ltd.     

Predictive models of fish microhabitat selection in multiple sites accounting for abundance overdispersion

Microhabitat selection models are frequently used in rivers to evaluate anthropogenic effects on aquatic organisms. Fish models are generally developed from few rivers, with debatable statistical treatments for coping with overdispersed abundance distributions. Analyses of data from multiple rivers are needed to test their transferability and increase their relevance for stakeholders. Using 3,528 microhabitats sampled in nine French rivers during 129 surveys, we developed models for 35 specific size classes of 22 fish species. We used mixed‐effects generalized linear models (accounting for multiple surveys), involving B‐spline transformations (accounting for nonlinear responses) and assuming a negative binomial distribution (accounting for abundance overdispersion). We compared models of increasing complexity: no selection (M1), an “average” selection similar in all surveys (M2), two models with different selection across surveys (M3–M4). Of 132 univariate cases (specific size classes by habitat), 63% indicated selection for depth, 71% for velocity, 45% for substratum size and 13% for substratum heterogeneity. A total of 50 models were retained, involving 26/35 specific size classes. Model fits indicated low explained deviance (R²MF < 0.19) and higher rank correlations (ρ < 0.69) between observed and modelled values. However, Bayesian posterior predictive checks validated these results since excellent fits would generate R²MF lower than 0.59 and ρ lower than 0.78. We found high transferability among rivers and dates, because (a) M2 was the most appropriate in 26/50 cases; (b) the R²MF and ρ values by M2 was, respectively, 72% and 75% of that explained by the complex M4 and (c) independent river cross‐validations showed good transferability. Bivariate models for selected specific size classes improved univariate model fits (ρ from 0.30 to 0.38). Overall, using a nonlinear mixed‐effect approach, our results confirmed the relevance of “average” models based on several rivers for developing helpful e‐flow tools. Finally, our modelling approach opens opportunities for integrating additional effects as the spatial distribution of competitors.     

Einsatz hochauflösender Bathymetriedaten aus luftgestützter Vermessung in der Abfluss- und Habitatmodellierung

Bathymetric surveys are an essential basis for investigations in river hydraulics. In this context, ecohydraulic studies represent an interpretation of the hydraulic situation in running waters with regard to the living conditions for their flora and fauna. With increasing computational performance and powerful models for describing the hydraulic situation, the expectations for basic surveys are rising. Against this backdrop and further reinforced by the stipulations of the European Water Framework Directive, the technology of Airborne Hydromapping (surveying with a water-penetrating laser system) was developed. With this technology it is possible to survey water bodies and riparian strips comprehensively and in high resolution (10–40 points/m²). The data generated can in turn be used to create detailed, high-resolution calculation meshes and therefore to accurately describe the hydraulic conditions in large river reaches. It can be used in both small-scale and large-scale contexts (e.g. habitat modeling or structural analysis), and also opens new avenues for monitoring applications.     

Interactive effects of cover and hydraulics on brown trout habitat selection patterns

Habitat modelling results are extremely sensitive to the habitat suitability criteria (HSC) used in the simulations. HSCs are usually expressed as univariate habitat suitability curves, although such univariate approach has been long questioned, since overlooking interactions between hydraulic variables may misrepresent the complexity of fish behaviour in habitat selection. It could lead to adopt erroneous flow management decisions based on misleading results. Furthermore, the interactive effects of hydraulic variables on habitat selection may be driven by the structural features of the channel, which determine cover availability. Therefore, we compared brown trout habitat selection patterns through multivariate resource selection functions (RSFs) in structurally contrasting rivers to unveil the interactive effects of hydraulics and cover elements and their consequences in univariate HSC results. Microhabitat preferences of young‐of‐the‐year (0+) trout were similar across fast and slow waters, meanwhile juvenile (1+) and adult (>1+) preferences significantly changed. RSFs for young‐of‐the‐year trout were consistent with univariate results and did not differ among water types. However, RSFs for older trout varied among water types and revealed complex interactions among hydraulic variables and between hydraulics and structural elements, which were not described accurately by univariate curves. Therefore, results suggest that interactions between water depth and current velocity have a significant effect on habitat selection patterns in juvenile and adult brown trout, this effect being controlled by cover availability. Copyright © 2008 John Wiley & Sons, Ltd.     

Response of aquatic macroinvertebrate density and diversity to wetland management and structure in the Montezuma Wetlands Complex,New York

We investigated how water management and other covariates affected aquatic macroinvertebrate density and diversity of wetlands in the Montezuma Wetlands Complex (MWC) of the Lake Ontario watershed, New York, USA. We conducted aquatic macroinvertebrate sampling during May–July in 2016–2018 to coincide with when juvenile wetland birds require these protein foods. Models that best explained aquatic macroinvertebrate density and taxon richness included water drawdown treatment, water depth, and water drawdown treatment from the prior year. Predicted mean density of aquatic macroinvertebrates was 117.2% greater in partial drawdown than passive wetlands (i.e., wetlands without active water removal) and increased by 516.2% with 15.5–48 cm increase in water depth. Density of aquatic macroinvertebrates also was ≥ 2.6 times greater in wetlands with a full drawdown the year prior. Taxon richness and Shannon Wiener Diversity Index (H′) varied positively with water depth, and there was greater diversity in partial drawdown than passive wetlands. Taxon richness was nearly 2 times greater in areas with full drawdown the year prior than those with partial drawdowns and passive wetlands. Other competing models for H′ also included negative effects of percentage monotypic cattail and invasive plant taxa. These findings are consistent with aquatic macroinvertebrate adaptation to dynamic wetland hydrology, and we recommend that managers actively manipulate hydrology to provide abundant and diverse food resources for birds at managed wetlands in the Great Lakes region.     

Macroinvertebrate assemblages in floodplain habitats of the lower river murray,South Australia

Macroinvertebrates were sampled in seven microhabitats (submerged woody debris, reeds, sedges, inundated grass, floating aquatic vegetation, lignum, and the unvegetated littoral) at thirteen sites representing six macrohabitats (single temporary and permanent ox-bow lakes (billabongs), fast and slow-flowing anabranches, backwaters, and the main channel) of the River Murray, and Australian lowland river. Sites were sampled in spring 1988, shortly after floodwaters had receded. Most of the 95 taxa collected were aquatic insects. Detritivores were most abundant in all macrohabitats except the temporary billabong where predators predominated. Scrapers were only abundant in the permanent billabong. The temporary billabong harboured the most species and individuals whereas slowly-flowing anabranches contained the fewest species and individuals. At the microhabitat level, most taxa and individuals occurred in stands of aquatic vegetation. The unvegetated littoral zone was the most depauperate microhabitat. Multivariate analyses illustrated the distinctiveness of the faunal assemblage found in the temporary billabong. Subsequent analyses of the permanently inundated macrohabitats indicated gradients related to current velocity and the extent to which the sites were continuous with the main river. Current velocity apparently determined assemblage composition at the macrohabitat scale whereas the structural complexity of submerged vegetation operated at the microhabitat scale. The relatively large number of taxa collected from this area emphasizes the importance of a range of macrohabitats and microhabitats to faunal diversity in a floodplain ecosystem. Although there was little faunal overlap between billabongs and the main river, billabongs probably serve as refuges for many lentic taxa that rely upon regular inundation to survive. Surveys of floodplain rivers for management purposes must include samples from aquatic habitats adjacent to the main channel because the fauna of the floodplain is potentially most threatened by regulation and alteration of the flooding regime.     

Hydraulic geometry of New Zealand rivers and its use as a preliminary method of habitat assessment

‘Downstream’ hydraulic geometry relationships describe the variation of water depth, velocity, and water surface width between rivers of different size at a characteristic discharge, whereas ‘at-a-station’ geometry describes the variation of hydraulic geometry with discharge within a reach. The instream flow incremental methodology (IFIM) also predicts the variation in water depth and velocity with discharge at a reach scale, so that hydraulic geometry relationships can potentially be used as a preliminary method of habitat assessment. Hydraulic geometry relationships were calculated from instream habitat surveys of 73 New Zealand river reaches with mean flows varying from 0.6 to 204 m³ s⁻¹ and an average gradient of 0.0047. The exponents of both at-a-station and downstream hydraulic geometry relationships were within the range of values reported in other international studies, although the exponents indicated that New Zealand rivers tended to experience greater changes in velocity and less in depth than the international average, probably because of high average gradient. The frequency distributions of water depth and velocity were positively skewed in most rivers, and on average the modal velocity was 90% of the mean velocity and the modal depth was 80% of mean depth. The use of at-a-station hydraulic geometry relationships for instream habitat assessment was compared to depth and velocity predictions using habitat simulation techniques (IFIM) in two streams. Measurements of stream width and depth at five cross-sections at two calibration discharges were used to establish at-a-station hydraulic geometry relationships. These predicted mean depth and velocity within 8% of the reach average values of the IFIM surveys within the range of calibration discharges and within 10–15% of the IFIM reach average when extrapolated beyond the calibration discharges. Hydraulic geometry can be used to indicate whether hydraulic conditions approach a ‘threshold’ such as a minimum acceptable depth or velocity, thus predicating the need for more extensive habitat survey and analysis. © 1998 John Wiley & Sons, Ltd.     

Applying spatial hydraulic principles to quantify stream habitat

Flow complexity plays an important role in stream ecology. Yet, a paucity of research exists with regard to quantifying flow complexity and relating it to the habitats that aquatic organisms utilize. Here we provide a generalized example of how two‐dimensional (2‐D) numerical hydraulic models and spatial hydraulic metrics can be used to simulate and quantify biologically important flow patterns within streams. A detailed topographic survey, incorporating meso‐scale topographic features (e.g. exposed boulders and bedrock outcrops) is performed for a small urbanized stream. The 2‐D hydraulic model RMA2 is then used to model the flow conditions within the stream reach. Model results demonstrate that the meso‐scale topographic features create highly complex flow patterns of potential biological importance. Recently developed spatial hydraulic metrics, based on hydraulic engineering principles (vorticity, circulation and kinetic energy gradients), are then used to quantify the various types of flow complexity found within the stream reach. In particular, spatial hydraulic metrics are used to quantify the stream reach's overall flow complexity and the flow complexity surrounding three chub mounds. A method for uniquely characterizing circulation zones is then developed and applied to five circulation zones within the study reach. The principles used in performing this study's topographic survey, spatial explicit hydraulic modelling and spatial hydraulic analyses, form a general framework for quantifying flow complexity in any stream. The ways in which using hydraulic models and spatial hydraulic metrics can help establish better habitat suitability criteria and design best management practices for use in stream and catchment area restoration projects is discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

卵砾石生态河床对河流水质净化和生态修复的效果

为研究卵砾石生态河床在河流原位水质净化和生态修复中的效果,选择位于宜兴市大浦镇的林庄港作为试验河道进行原位观测,对比分析了卵砾石生态河床河段和自然河床河段中的生源要素变化规律和水生生物生长状况。试验结果表明:卵砾石生态河床河段对污染物质的截留效果明显好于自然河床河段,对氨氮和总磷的截留率可分别达到37%和25%,卵砾石生态河床的构建可显著提高河道的自净能力;卵砾石生态河床河段水生植被的生长密度和覆盖率均达到良好的水平,大型底栖无脊椎动物在敏感物种数、分类单元数和生物数量密度等方面均优于自然河段的;卵砾石生态河床为水生植物、底栖动物和附着生物等水生生物提供了适宜的栖息环境,对河流生态系统的健康起到了较好的改善作用。     

Macroinvertebrate assemblages of littoral habitats in the Macquarie and Mersey rivers,Tasmania: Implications for the management of regulated rivers

Littoral habitats in large rivers are influenced to varying degrees by changes in discharge. Irrigation abstractions can increase the amount of habitat that would naturally be dewatered during low flow periods and therefore it is important to have some knowledge of the potential impact this may have on riverine macroinvertebrates. The macroinvertebrate assemblages of common littoral habitats in riffles, pools and runs in two reaches each of the Macquarie and Mersey Rivers, northern Tasmania, Australia were compared from samples collected during the low flow and irrigation season, between December 1991 and April 1992. The area under water of these habitats, riffle substrata, macrophyte beds and coarse woody debris, responded differently to changes in discharge. Within a reach, the same taxonomic groups often dominated the total number of macroinvertebrates for all habitats, but there were differences in the proportions contributed by these taxa to the different habitats. In general, taxa characteristic of slow-flowing or lentic habitats, such as ostracods and amphipods, were dominant in macrophyte beds in pools and runs, whereas taxa such as larval elmid beetles and hydropsychid caddisflies were dominant in riffles. A substantial component of the fauna from each habitat within a reach was unique to that habitat, but there was always a similar number of taxa common to all habitats. Classification and ordination grouped samples from both rivers firstly by habitat and secondly by month and reach. Total density and family richness of invertebrates differed by reach, habitat and month in both rivers, except for richness in the Mersey River where habitat was not significant. Differences in densities and numbers of invertebrate families among habitats were not consistent between reaches for each river. This study has highlighted the differences in macroinvertebrate assemblages of several littoral habitats in two lowland rivers in Tasmania. Differences in taxonomic composition, density and richness among habitats within reaches strongly imply the uniqueness of these habitats in terms of the invertebrate faunas that occupy them. We suggest that if maintenance of biotic diversity is an aim of instream flow management, water allocations that address low flows should place a high priority on the maintenance of a diversity of habitats.     

Juvenile masu salmon in a regulated river

We examined the relationship between the physical environment and habitat use of juvenile masu salmon, Oncorhynchus masou, in the Nobori River in Hokkaido, Japan to provide a perspective for the conservation of fish habitat in regulated streams. The study was undertaken during the autumn and winter, with an emphasis on the hierarchy of three spatial scales: microhabitat, channel‐unit and reach scales. The microhabitat‐scale analysis indicated juvenile masu salmon preferred a midstream habitat type, with a greater depth (Avg. ± SD: 35.4 ± 14.2 cm) and high (43.4 ± 23.1 cm s^?1) and uniform current velocities during the autumn, and a channel margin habitat type with a moderate current (about 20 cm s^?1) and submerged cover during winter. In addition, different cover types have different roles in determining juvenile salmon distributions during winter. Grass cover had extremely high carrying capacities, whereas coarse substrate cover provided winter habitat for larger juvenile salmon. Channel‐unit scale analyses showed that abundance of juvenile salmon tended to be higher in pools than runs in the autumn through winter. Reach‐scale analysis showed that abundance and mean body length of juvenile salmon significantly differed between differently regulated reaches during winter, associated with the dominant cover type in each reach. This study demonstrated that the habitat conditions determining juvenile masu salmon distribution differ according to the season and scale of analysis. Therefore, for conservation of fish communities, it is important to evaluate and conserve or create fish habitats in regulated reaches, with a focus on the hierarchy of spatial scales and seasonal differences. Copyright © 2007 John Wiley & Sons, Ltd.     

History and review of the habitat suitability criteria curve in applied aquatic ecology

Hydraulic microhabitat assessment is a category of environmental flow tools (e.g., Physical Habitat Simulation system and other methodologically similar software) that, at its core, uses habitat suitability criteria (HSC) to link values of point hydraulic variables (usually depth, velocity, and substrate/cover) to habitat values for target life stages. Although this assessment tool has been used worldwide for decades, the history of the HSC curve is relatively unknown because the foundational information is predominantly contained in obscure and often unpublished reports. We review the history of the HSC concept in applied aquatic ecology to clarify its scientific pedigree, ensure its proper use, and build a foundation for future research. We begin the review with the formative decades of the 1950's through the 1970's, when consumptive‐based western USA water law conflicted with conservation traditions and natural resource management objectives, although water allocation issues date back at least to the 19th century. By analysing the history of the HSC concept, we aim to establish the biological, hydrologic, and geomorphological conditions that must be met for the HSC concept to be successfully employed. In spite of its documented assumptions and limitations, the HSC concept will likely continue to be a useful tool to help address water resources allocation issues in defined hydrologic and geomorphic settings. We conclude that HSC‐based methodologies should be considered as one of several environmental flow approaches involved in sustainable water resources management.     

An approach to the synthesis of qualitative ecological information from aquatic coleoptera communities

A list of 196 Coleoptera taxa, larvae and adults, covering 113 species, was obtained from several surveys of a flood plain of the Rhô river. From published reports and personal experience, each taxon is linked with the modalities of nine environmental and three biological variables. The resulting 12 ecological profiles for 196 taxa are analysed by correspondence analysis. The simultaneous ordination of the taxa and variables allows presentation of the more synthetic correspondence between the Coleoptera and their ecological and biological characteristics. The niche dimensions of the 12 variables tested here are organized along a current-substrate gradient, from stones in rapid flow to mud in still water, which is associated with the other ecological conditions. This ordination reflects environmental conditions in a transverse direction, particularly from the central channel to the furthest annexes of the river. The Coleoptera are shown to be describers of the connectivity with the main channel. The 196 studied taxa are positioned along the gradient. They are subdivided into seven faunal groups based on their habitat range or niche width. The larger species are confined to the stagnant side of the gradient. Other variables, such as feeding and vertical distribution, clearly separate carnivores from herbivores and also larvae from adults. The next step of this study will be to extend these investigations to other functional variables and to all the species of Coleoptera in France. The information given by the Coleoptera will then be compared with actual field measurements.     

Cascade macroinvertebrate assemblages for in‐stream flow criteria and biomonitoring of tropical mountain streams

Few comprehensive studies on stream assessment and biomonitoring have been conducted in tropical, freshwater watersheds. Currently under threat from climate change, urbanization and increasing freshwater demands, there is a need for innovative approaches to tropical watershed assessment and management. This study investigated cascade habitat macroinvertebrate communities among four tropical mountain streams with the goal of enhancing future efforts to identify flow biocriteria for watersheds of Polynesia. Cascade macroinvertebrate communities were compared between streams of differing size and magnitude of flow removal to evaluate the biological effects of water withdrawal on benthic communities. Two cascade microhabitats, identified as torrenticolous and amphibious, were evaluated for macroinvertebrate community differences and presence of native taxa among watersheds. Cascade habitat in general was reduced, by as much as 98%, in downstream reaches, having a significant impact on the stream ecosystem physical template important for native stream communities. In addition, two‐way ANOVA results revealed no main effects, but significant interactions of watershed size and flow removal on mean macroinvertebrate density for torrenticolous microhabitats; however, the opposite was true for the amphibious microhabitat. Diversity was significantly higher under undiverted flow conditions (t = 4.21, df = 272, p = 0.0004) and in torrenticolous microhabitats (t = 3.86, df = 272, p < 0.0001) over the entire study period. The amphibious microhabitat was composed of 39% native taxa, while the torrenticolous microhabitat contained <7%. This study provides new options for biomonitoring of native populations in Polynesian watersheds. Further studies that support the development of in‐stream flow criteria to preserve cascades are important to understanding the role of this habitat in tropical stream ecosystem function. Copyright © 2010 John Wiley & Sons, Ltd.     

基于水生态保护目标的河道内生态需水量研究

生态水力学法计算生态需水量需要依据河流生境特征、水生生物保护目标对生境的需求等实际情况灵活应用。本文以楠溪江干流河道内生态需水量计算为例,分析自然条件下生境条件与标准推荐方法的差别,探讨针对水生态保护目标的河道内生态需水量综合确定的思路和方法。楠溪江干流水文情势、河势河型较为稳定,是洄游性鱼类香鱼的重要栖息地,生态需水量除可参照水文学、水力学方法确定外,还应分时段、分河段考虑香鱼洄游对水流条件的需求。本文提出的生态需水量以维持良好生境条件为目标,以满足基本生态需求为基础,可为流域水资源开发利用提供参考。     

生态水力学及其在水利工程生态环境效应模拟调控中的应用

生态水力学是水力学、生物学和生态学的交叉学科,重点研究水动力对水生态系统的作用机制以及水生态健康的水力调控技术。生态水力学一方面研究水动力条件变化对物质生物地球化学过程的影响及生态系统中物种构成、栖息地分布、生态功能的效应,另一方面研究水生态系统的演变对水力情势的影响。本文围绕水电开发的生态环境效应模拟与调控,重点论述生态水力学研究的发展现状、热点难点、工程应用及前沿展望。