Application and testing of a procedure to evaluate transferability of habitat suitability criteria

A procedure designed to test the transferability of habitat suitability criteria was evaluated in the Cache la Poudre River, Colorado. Habitat suitability criteria were developed for active adult and juvenile rainbow trout in the South Platte River, Colorado. These criteria were tested by comparing microhabitat use predicted from the criteria with observed microhabitat use by adult rainbow trout in the Cache la Poudre River. A one-sided X² test, using counts of occupied and unoccupied cells in each suitability classification, was used to test for non-random selection for optimum habitat use over usable habitat and for suitable over unsuitable habitat. Criteria for adult rainbow trout were judged to be transferable to the Cache la Poudre River, but juvenile criteria (applied to adults) were not transferable. Random subsampling of occupied and unoccupied cells was conducted to determine the effect of sample size on the reliability of the test procedure. The incidence of type I and type II errors increased rapidly as the sample size was reduced below 55 occupied and 200 unoccupied cells. Recommended modifications to the procedure included the adoption of a systematic or randomized sampling design and direct measurement of microhabitat variables. With these modifications, the procedure is economical, simple and reliable. Use of the procedure as a quality assurance device in routine applications of the instream flow incremental methodology was encouraged.     

Using habitat guilds to develop habitat suitability criteria for a warmwater stream fish assemblage

The diversity of fish species found in warmwater stream systems provides a perplexing challenge when selecting species for assessment of instream flow needs from physical habitat analyses. In this paper we examined the feasibility of developing habitat suitability criteria (HSC) for the entire fish community of a warmwater stream using habitat guilds. Each species was placed a priori into a guild structure and habitat data were collected for depth, velocity, Froude number, distance to cover, embeddedness and dominant and subdominant substrate. Correct guild classification was tested with linear discriminant analysis for each species. Correct classification based on habitat‐use data was highest for riffle and pool‐cover guilds, whereas the fast‐generalist and pool‐run classes, the broader niche guilds, were more frequently misclassified. Variables most important for discriminating guilds were Froude number, velocity and depth in that order. Nonparametric tolerance limits were used to develop guild suitability criteria for continuous variables and the Strauss linear index was used for categorical variables. We recommend the use of a wide array of variables to establish more accurate habitat analysis. Additionally, guild HSC can be developed with similar effort to that needed to develop HSC for a small number of individual species. Results indicate that a habitat guild structure can be successfully transferred to another river basin and that habitats for a diverse fish assemblage can be adequately described by a small number of habitat guilds. This approach represents an alternative for incorporating entire fish assemblages into habitat analyses of warmwater stream systems. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and evaluation of bioenergetic-based habitat suitability criteria for trout

We constructed energetic models of habitat use for 82–322 g rainbow trout (Oncorhynchus mykiss) in a large regulated river, and 8–28 g Colorado River cutthroat trout (O. clarki pleuriticus) in a small headwater stream, to determine if observed summer habitat use by these species could be attributed to net energy acquisition, and to develop habitat suitability criteria based on net energy gain. Metabolic models of energy expenditure were derived from literature sources, but measurements of energy availability were site-specific. From the energy models, we assigned a suitability value of 1.0 to the entire range of velocities where positive net energy gains were predicted, and a suitability value of zero to velocities where negative net energy gains were predicted. Predicted net energy gain velocities were compared with observed velocities used by each species. For rainbow trout, the energetic model predicted energetically profitable velocities ranging from 5 to 45 cm s⁻¹. Predicted velocities were similar to velocities used by rainbow trout. This indicated that rainbow trout, as a group, were using energetically profitable stream locations, but some rainbow trout used non-profitable velocities. For Colorado River cutthroat trout, the energetic model predicted energetically profitable velocities ranging from 5 to 45 cm s⁻¹; however, Colorado River cutthroat trout used significantly lower velocities than predicted. The dissimilarity between velocities predicted and used by Colorado River cutthroat trout may be attributed to their inability to utilize energetically profitable velocities available in the stream because of depth restrictions The results suggest that the predictive abilities of energetic models vary between streams because of differences in depth and velocity availability. © 1997 John Wiley & Sons, Ltd.     

PHABSIM modelling of Atlantic salmon spawning habitat in an upland stream: testing the influence of habitat suitability indices on model output

This paper reports the findings of research designed to assess the ability of PHABSIM to predict Atlantic salmon Salmo salar spawning habitat in the Girnock Burn, a tributary of the River Dee in northeast Scotland. It used an 18‐year spawning data record to assess: (a) the ability of PHABSIM to predict between‐year differences in the availability of habitat at the study site; (b) the ability of PHABSIM to predict patterns of relative suitability across the site; and (c) the influence of different Habitat Suitability Indices (HSIs) on the model's predictions with respect to (a) and (b). Predictions of between‐year and within‐site habitat availability based on ‘utilization’ and ‘preference’ HSIs developed in the Dee catchment corresponded significantly (chi‐squared and regression tests, P < 0.05) with the use of the site by spawning fish. However, predictions based on utilization HSIs developed in streams in southern England did not correspond significantly with patterns of site use. Results of the study indicate that PHABSIM is capable of predicting Atlantic salmon spawning habitat in upland streams such as the Girnock, but that the use of appropriate HSIs is critical. Copyright © 2005 John Wiley & Sons, Ltd.     

A review of statistical methods for the evaluation of aquatic habitat suitability for instream flow assessment

Habitat models serve three main purposes: First, to predict species occurrences on the basis of abiotic and biotic variables, second to improve the understanding of species‐habitat relationships and third, to quantify habitat requirements. The use of statistical models to predict the likely occurrence or distribution of species based on relevant variables is becoming an increasingly important tool in conservation planning and wildlife management. This article aims to provide an overview of the current status of development and application of statistical methodologies for analysing the species‐environment association, with a clear emphasis on aquatic habitat. It describes the main types of univariate and multivariate techniques available for analysis of species‐environment association, and specifically focuses on the assessment of the strengths and weaknesses of the available statistical methods to estimate habitat suitability. A second objective of this article is to propose new approaches using existing statistical methods. A wide array of habitat statistical models has been developed to analyse habitat‐species relationship. Generally, physical habitat is dependent on more than one variable (e.g. depth, velocity, substrate, cover) and several suitability indices must be combined to define a composite index. Multivariate approaches are more appropriate for the analysis of aquatic habitat as they inherently consider the interrelation and correlation structure of the environmental variables. Ordinary multiple linear regression and logistic regression are popular methods often used for modelling of species and their relationships with environment. Ridge regression and Principal component regression are particularly useful when the independent variables are highly correlated. More recent regression modelling paradigms like generalized linear models (GLMs) present advantages in dealing with non‐normal environmental variables. Generalized additive models (GAMs) and artificial neural networks are better suited for analysis of non‐linear relationships between species distribution and environmental variables. The fuzzy logic approach presents advantages in dealing with uncertainties that often exist in habitat modelling. Appropriate methods for analysis of multi‐species data are also presented. Finally, the few existing comparative studies for predictive modelling are reviewed, and advantages and disadvantages of different methods are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Spatial scales in instream flow modeling: Why and how to use ecologically appropriate resolutions

This paper discusses why and how to use ecologically appropriate spatial resolutions (e.g., cell size or range of cell sizes) when modeling instream flow effects on aquatic animals. Resolution is important because relations between habitat and animal habitat use vary with spatial resolution, and different habitat variables may best predict habitat use at different resolutions. Using appropriate resolutions consistently would bring clarity and coherence to how we quantify and model habitat characteristics and habitat use by fish, facilitate the use of standard and more credible measures of habitat preference, incorporate more fisheries knowledge to improve models for different kinds of fish, and avoid well-known (and perhaps unknown) biases. Doing so involves describing habitat, and habitat use by fish, with spatially explicit measures with clear resolutions; using the same resolution for physical habitat and fish habitat use; selecting that resolution for ecological reasons; and using habitat variables and fish observation methods appropriate for the resolution. The choice of resolution considers factors such as how much space fish use for specific activities and the size of important habitat patches. For drift-feeders, cell sizes and fish habitat use observations should use a resolution no smaller than feeding territories. Piscivores typically hunt over large areas so should be modeled with larger habitat units. Models of small and less-mobile organisms (e.g., benthic invertivores) may need fine resolutions to capture the small areas of unusual habitat they depend on. Because of such differences, instream flow studies (like any spatial ecology exercise) should clearly state what resolution(s) they use and why.     

Effects of variation in streamflow and channel structure on smallmouth bass habitat in an alluvial stream

We evaluated the effects of streamflow‐related changes in channel shape and morphology on the quality, quantity, availability and spatial distribution of young‐of‐year and adult smallmouth bass Micropterus dolomieu habitat in an alluvial stream, the Baron Fork of the Illinois River, Oklahoma. We developed Habitat Suitability Criteria (HSC) for young‐of‐year and adult smallmouth bass to assess changes in available smallmouth bass habitat between years, and compare predicted smallmouth bass Weighted Usable Area (WUA) with observed WUA measured the following year. Following flood events between 1999 and 2000, including a record flood, changes in transect cross‐sectional area ranged from 62.5% to 93.5% and channel mesohabitat overlap ranged from 29.5% to 67.0% in study three study reaches. Using Physical HABitat SIMulation (PHABSIM) system analysis, we found that both young‐of‐year and adult smallmouth bass habitat were differentially affected by intra‐ and inter‐annual streamflow fluctuations. Maximum WUA for young‐of‐year and adults occurred at streamflows of 1.8 and 2.3 m³ s^?1, respectively, and WUA declined sharply for both groups at lower streamflows. For most microhabitat variables, habitat availability was similar between years. Habitat suitability criteria developed in 1999 corresponded well with observed fish locations in 2000 for adult smallmouth bass but not for young‐of‐year fish. Our findings suggest that annual variation in habitat availability affects the predictive ability of habitat models for young‐of‐year smallmouth bass more than for adult smallmouth bass. Furthermore, our results showed that despite the dynamic nature of the gravel‐dominated, alluvial Baron Fork, HSC for smallmouth bass were consistent and transferable between years. Published in 2008 by John Wiley & Sons, Ltd.     

Development of habitat suitability criteria for trout in small streams

We observed 2863 trout in the wild to determine habitat utilization in small streams of the Kings River basin in California's Sierra Nevada mountains. The habitat utilization data were used to develop habitat suitability functions that provide input variables to the instream flow incremental methodology (IFIM) habitat assessment model of the U.S. Fish and Wildlife Service. Observations of habitat utilization of rainbow trout (Salmo gairdneri), brown trout (Salmo trutta), and brook trout (Salvelinus fontinalis) were obtained during the summer months of 1983 and 1984. The observations were made in small streams with discharges ranging from 0.7 m³ s^?1 to 0.03 m³ s^?1. The streams are at elevations of 1250 to 2530 m. Equal effort was applied to observing undisturbed trout in all habitat types. Snorkeling proved to be the most effective method of observation. Individual trout of all species and life stages were most often observed in the lower half of the water column, utilizing low-velocity currents of less than 3.0 cm s^?1. From the depth and velocity utilization data, several forms of habitat suitability functions were developed and evaluated:

• 1 Univariate depth and velocity functions derived from frequency histogram analysis.
• 2 Univariate depth and univariate velocity exponential polynomial models.
• 3 Bivariate depth and velocity exponential polynomial models.

Univariate exponential polynomial models provided the best fit to the data for each species, based on visual comparisons of response surfaces and contour plots, and comparisons of computed sums of squared errors. Bivariate models fitted to the data resulted in greater sums of squared errors than multiplicative aggragation of univariate models, and frequently predicted utilization at zero depth. The habitat suitability functions derived from the univariate exponential polynomial models provided the best input to the IFIM habitat assessment models.     

Differences in physical habitat simulation system modelling results using benthic or pelagic fish species as indicators in Peruvian Andes–Amazon rivers

Aquatic organisms with different adaptations are used as indicators in physical habitat simulation system models. Those adaptations are critical for determining the shape of the weighted usable area/width curve and for recommending values of environmental flows. The main objective of this study is to compare the use of benthic native species (Astroblepus taczanowskii and Astroblepus vanceae) versus the introduced Oncorhynchus mykiss (rainbow trout) as target indicators for PHABSIM modelling in the Andean–Amazon piedmont rivers. We used adjusted probability distribution functions with L‐moments analyses for developing curves of use and preference to evaluate the efficiency of each indicator. Two hydraulic modelling sections were established in the Ulcumayo River with 21 and 27 cross sections, respectively. Native benthic species are usually dominant but scarcely used as focus organisms for environmental flows modelling. These species are associated with fast running and shallow waters, which makes them potentially more sensitive to the effects of flow reduction. Our results indicated that the native species were more restricted to velocity and depth than O. mykiss. Using selection curves in PHABSIM modelling, it is required between 10% to 94% of the mean monthly flow to preserve 90% of the available habitat for Astroblepus during the dry season (May to November). In contrast, rainbow trout requires 5% to 88% of the mean monthly flow. We conclude that a multispecies approach is useful for determining the required environmental instream flows contributing to a better sustainable condition for the Neotropical mountain rivers.     

四大家鱼产卵栖息地适宜度与大坝泄流相关性分析

为探究三峡—葛洲坝水库联合调度运行后,长江四大家鱼对不同大坝泄流工况下产卵栖息地水动力环境的适宜性,在构建长江四大家鱼主要产卵栖息地水动力数学模型及产卵栖息地适宜度评价模型基础上,针对大坝不同运行参数进行大坝泄流方式与四大家鱼产卵栖息地适宜度相关性分析。结果表明,大坝泄流量为10 000~15 000 m~3/s时,四大家鱼产卵栖息地具有较高的适宜度;在流量基数为10 000~15 000 m~3/s,日均流量增长率为1 000~1 500 m~3/s时,四大家鱼产卵栖息地同样有较高的产卵栖息适宜度。研究结果可为构建考虑家鱼自然繁殖的水库生态调度方式提供参考。     

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.     

沈阳市水生态问题定量研究

利用遥感(RS)和地理信息系统(GIS)为主要技术手段,配合实地调查验证、文献资料收集、调查表、监测等多种技术方法,对沈阳市水生态问题进行了系统调查与定量研究。结果表明:2005年沈阳市部分地区水土流失严重,部分主要河流及其支流断流,湿地总面积比1979年增加了50.86%,但北部呈萎缩趋势,水环境污染问题突出,辖区内绝大多数河流为Ⅴ类和劣Ⅴ类水质,且很多河段已丧失天然河流的生态功能。     

Ecosystem‐based environmental flow assessment in a Greek regulated river with the use of 2D hydrodynamic habitat modelling

Despite the long‐term research on the use of hydraulic‐hydrodynamic habitat models (HHMs) for predicting the response of aquatic biota to habitat alteration, their practical application in model‐based environmental flow assessments (EFAs) has been limited due to reasons mainly associated with cost‐effectiveness, time‐efficiency, required expertise, and availability of hydroecological information. In this study, we demonstrate a cost‐effective and time‐efficient application of a benthic‐invertebrate, two‐dimensional, fuzzy rule‐based EFA in a 277‐m long reach in the downstream route of a regulated river in western Greece. Apart from developing ecosystem‐based environmental flow (eflow) scenarios, we highlight the valuable features of HHMs, comment on their disadvantages, and propose working solutions to overcome them. The results of the study show that the hydrology‐based eflow of 0.2 m³/s, initially proposed by the managing authorities, is not sufficient to ensure the long‐term functionality of the downstream benthic communities, as the ecosystem‐based eflow ranged between 0.6 and 2 m³/s. As social resilience relies heavily on ecological resilience, ecosystem‐based approaches can ensure the sustainability of aquatic ecosystems. This study demonstrates, inter alia, that HHMs‐based EFAs can be implemented cost‐effectively and time‐efficiently to serve as an accurate scientific basis for water managers and stakeholders, in search of the fine balance between anthropogenic water demand and long‐term ecosystem integrity and functionality.     

Habitat suitability curves for brown trout (Salmo trutta fario L.) in the River Adda,Northern Italy: comparing univariate and multivariate approaches

Habitat suitability of brown trout (Salmo trutta fario) was studied in the upper portion of the Adda River, Northern Italy. Measurements were made for 528 individuals distributed in two life‐stage classes, adult and juvenile, based on body length. In order to provide basic biological information for the physical habitat simulation (PHABSIM) system of the instream flow incremental methodology (IFIM) in the Italian regulated rivers, habitat suitability curves (HSCs) have been developed with respect to several microhabitat riverine parameters. Initially, current velocity, water depth, substrate class size and cover were analysed with an univariate approach, then bivariate habitat suitability models were developed from depth and velocity data. The comparison of experimental univariate HSCs with those from the literature outlined some differences that can essentially be explained by characteristics of the investigated river, confirming the necessity of using site‐specific curves in relation to each experimental study area. To compare the univariate and bivariate approaches, the weighted usable area (WUA)–discharge relationships were calculated using both types of HSCs. Response curves obtained from the two approaches turned out to be quite different. In PHABSIM habitat modelling, HSCs univariate functions need to be aggregated to produce the WUA–discharge relationship. A multiplicative criterion is generally used for the combined suitability factor; by means of this aggregation criterion all variables have equal weight. According to bivariate models, depth is much more important than velocity in defining habitat suitability requirements. Copyright © 2001 John Wiley & Sons, Ltd.     

基于黄河鲤栖息地水文-生态响应关系的黄河下游生态流量研究

本研究采用野外生物监测、栖息地同步观测和实验室控制实验等技术手段,应用生物学、鱼类生态学、生态水力学、水文学等多学科理论,基于河流栖息地模拟法,研究了黄河下游指示物种黄河鲤生态学特性及其栖息生境与流速、水深、水温等水文水环境因子之间的关系,将径流条件与目标物种不同生长阶段生物学信息相结合,建立了代表物种繁殖期、越冬期栖息地适宜度指数,构建了黄河下游重点河段河流栖息地模型,建立了指示物种栖息地状况与河川径流条件定量响应关系,提出黄河下游花园口和利津断面繁殖期最小生态流量为300 m³/s和100 m³/s、适宜生态流量为600～700 m³/s和190～250 m³/s。该研究在水生生物习性及其与河川径流响应关系方面实现突破,解决了黄河生态需水研究中关键技术问题。     

长江中游典型河段底栖动物的物理栖息地模型构建与应用

考虑水生生物生境需求的物理栖息地模型被认为是评估河流流量变化对水生态系统影响的最可信的方法之一。本研究选取长江干流含有河漫滩的监利江段为实例,建立底栖动物各类群的物理栖息地模型,计算变化流量下栖息地适宜面积的时间序列,并据此进行生态流量决策。结果显示长江中游底栖动物最敏感的环境参数是流速,适宜范围为0～0.2 m/s;其次是水深,适宜范围为0～6 m。在考虑敏感环境参数的前提下,得出监利江段底栖动物的最佳生态流量为20 000 m3/s。三峡大坝蓄水后枯水期和平水期底栖动物适宜面积的低值部分减小,丰水期适宜面积增加。为了保护底栖动物栖息地,建议三峡大坝在防洪蓄水的同时能兼顾底栖动物的生态流量需求,调节枯水期和平水期的流量,让监利江段接近4000 m3/s,丰水期接近20 000 m3/s。在枯水年增大枯水期和平水期的流量,平水年增大枯水期的流量,丰水年减少丰水期的流量。本研究方法可以供长江其他河段目标物种的生态流量决策和生态修复方案设计参考。     

Coupling interaction between biodiversity and aquatic habitat area in Western Route Project vicinity

The Western Route of the South-to-North Water Transfer Project will divert water from the upper Yangtze River and its tributaries,the Dadu River and Yalong River,to the upper Yellow River.The project may ease the water shortage in the Yellow River Basin.However,it may also have some effects on the ecosystem in the upper Yangtze River Basin.Benthic invertebrates play an important role in the river ecosystem,particularly in the circulation of materials and nutrition.Benthic invertebrates are widely used to quickly assess river ecosystems because of their rapid response to changes in the water environment.The diversity of benthic invertebrates is closely associated with the aquatic habitat area.This study examined this interaction by sampling the benthic invertebrates in an expanding area.The conclusions are that the diversity of benthic invertebrates begins to decrease when the aquatic habitat area is reduced to 45% of the original area,and decreases dramatically when the aquatic habitat area is reduced to 10% of the original area.The aquatic habitat area should be kept at more than 45% of the original area in order to maintain the significant diversity of benthic invertebrates.     

Recent habitat association and the historical decline of Notropis simus pecosensis

Small‐bodied, riverine minnows that historically characterized fish assemblages of Great Plains rivers in North America have declined because of river fragmentation, dewatering, river channel degradation, river salinization and nonnative species introductions. The Pecos bluntnose shiner Notropis simus pecosensis, a member of this guild, persists in one segment of the Pecos River, New Mexico, USA. We characterized habitat associations for the species at two spatial scales. In general, N. s. pecosensis associated with fluvial habitats, but velocity association depended on body size, with larger individuals using swifter habitats. All N. s. pecosensis associated with relatively low depths (3–51 cm), which were most abundant in sites with relatively wide river channels (>25 m), especially when discharge was between 0.5 and 4.0 m³ s^?1. The Pecos River sub‐segment that is occupied by the core population of N. s. pecosensis (V‐ii) had a unique combination of being buffered from direct dam effects by intervening segments and sub‐segments, high sub‐segment length, substantial sediment inputs from numerous uncontrolled tributaries, substantial base flow provided by irrigation return flows and groundwater inflows, high channel width in relation to discharge and low salinity. Although no unoccupied Pecos River segment appears to be suitable for N. s. pecosensis, habitat restoration opportunities exist within all occupied sub‐segments (V‐i, V‐ii and V‐iii) via base flow enhancement and river channel restoration. Restoration that offsets chronic effects of dams may be necessary to conserve the species. Restoration would also benefit other rare riverine minnows that coexist with N. s. pecosensis. Copyright © 2008 John Wiley & Sons, Ltd.     

Assessing downstream aquatic habitat availability relative to headwater reservoir management in the Henrys Fork Snake River

Reservoirs are sometimes managed to meet agricultural and other water demands, while also maintaining streamflow for aquatic species and ecosystems. In the Henrys Fork Snake River, Idaho (USA), irrigation-season management of a headwater reservoir is informed by a flow target in a management reach ~95 km downstream. The target is in place to meet irrigation demand and maintain aquatic habitat within the 11.4 km management reach and has undergone four flow target assignments from 1978 to 2021. Recent changes to irrigation-season management to maximize reservoir carryover warranted investigation into the flow target assignment. Thus, we created a streamflow-habitat model using hydraulic measurements, habitat unit mapping, and published habitat suitability criteria for Brown Trout (Salmo trutta), Rainbow Trout (Oncorhynchus mykiss), and Mountain Whitefish (Prosopium williamsoni). We used model output to compare habitat availability across two management regimes (1978–2017 and 2018–2021). We found that efforts to minimize reservoir releases in 2018–2021 did not reduce mean irrigation-season fish habitat relative to natural flow, but did reduce overall fish habitat variability during the irrigation season compared to streamflow management in 1978–2017. Field observations for this research led to an adjusted flow target in 2020 that moved the target location downstream of intervening irrigation diversions. Using our model output, we demonstrated that moving the location of the target to account for local irrigation diversions will contribute to more consistently suitable fish habitat in the reach. Our study demonstrates the importance of site selection for establishing environmental flow targets.