Assessing historical fish community composition using surveys, historical collection data, and species distribution models

Accurate establishment of baseline conditions is critical to successful management and habitat restoration. We demonstrate the ability to robustly estimate historical fish community composition and assess the current status of the urbanized Barton Creek watershed in central Texas, U.S.A. Fish species were surveyed in 2008 and the resulting data compared to three sources of fish occurrence information: (i) historical records from a museum specimen database and literature searches; (ii) a nearly identical survey conducted 15 years earlier; and (iii) a modeled historical community constructed with species distribution models (SDMs). This holistic approach, and especially the application of SDMs, allowed us to discover that the fish community in Barton Creek was more diverse than the historical data and survey methods alone indicated. Sixteen native species with high modeled probability of occurrence within the watershed were not found in the 2008 survey, seven of these were not found in either survey or in any of the historical collection records. Our approach allowed us to more rigorously establish the true baseline for the pre-development fish fauna and then to more accurately assess trends and develop hypotheses regarding factors driving current fish community composition to better inform management decisions and future restoration efforts. Smaller, urbanized freshwater systems, like Barton Creek, typically have a relatively poor historical biodiversity inventory coupled with long histories of alteration, and thus there is a propensity for land managers and researchers to apply inaccurate baseline standards. Our methods provide a way around that limitation by using SDMs derived from larger and richer biodiversity databases of a broader geographic scope. Broadly applied, we propose that this technique has potential to overcome limitations of popular bioassessment metrics (e.g., IBI) to become a versatile and robust management tool for determining status of freshwater biotic communities.     

Spatial and temporal heterogeneity of the bacterial communities in stream epilithic biofilms

The spatial and temporal variability in bacterial communities within freshwater systems is poorly understood. The bacterial composition of stream epilithic biofilms across a range of different spatial and temporal scales both within and between streams and across the profile of individual stream rocks was characterised using a community DNA-fingerprinting technique (Automated Ribosomal Intergenic Spacer Analysis, ARISA). The differences in bacterial community structure between two different streams were found to be greater than the spatial variability within each stream site, and were larger than the weekly temporal variation measured over a 10-week study period. Greater variations in bacterial community profiles were detected on different faces of individual stream rocks than between whole rocks sampled within a 9-m stream section. Stream temperature was found to be the most important determinant of bacterial community variability using distance-based redundancy analysis (dbRDA) of ARISA data, which may have broad implications for riparian zone management and ecological change as a consequence of global warming. The combination of ARISA with multivariate statistical methods and ordination, such as multidimensional scaling (MDS), permutational manova and RDA, provided rapid and effective methods for quantifying and visualising variation in bacterial community structure, and to identify potential drivers of ecological change.     

Reconstructing riverine mesohabitat unit composition using fish community data and an autecology matrix

This research proposes a simplified method for estimating the mesohabitat composition that would favour members of a given set of aquatic species. The simulated composition of four types of mesohabitat units (deep pool, shallow pool, deep riffle and shallow riffle) could guide the design of in‐stream structures in creating pool‐riffle systems with ecological reference. Fish community data and an autecology matrix are used to support the development of a stream mesohabitat simulation based on regression models for reaches in mid to upper‐order streams. The fish community‐mesohabitat model results constitute a reference condition that can be used to guide stream restoration and ecological engineering decisions aimed at maintaining the natural ecological integrity and diversity of rivers.     

Approximating Nature's Variation: Selecting and Using Reference Information in Restoration Ecology

Restoration ecologists use reference information to define restoration goals, determine the restoration potential of sites, and evaluate the success of restoration efforts. Basic to the selection and use of reference information is the need to understand temporal and spatial variation in nature. This is a challenging task: variation is likely to be scale dependent; ecosystems vary in complex ways at several spatial and temporal scales; and there is an important interaction between spatial and temporal variation. The two most common forms of reference information are historical data from the site to be restored and contemporary data from reference sites (sites chosen as good analogs of the site to be restored). Among the problems of historical data are unmeasured factors that confound the interpretation of historical changes observed. Among the problems of individual reference sites is the difficulty of finding or proving a close match in all relevant ecological dimensions. Approximating and understanding ecological variation will require multiple sources of information. Restoration, by its inherently experimental nature, can further the understanding of the distribution, causes, and functions of nature's variation.     

Turquoise is the new green: Restoring and enhancing riparian function in the Anthropocene

Riparian ecosystems are hotspots for ecological restoration globally because of the disproportionately high value and diversity of the ecological functions and services which they support and their high level of vulnerability to anthropogenic pressures, including climate change. Degraded riparian ecosystems are associated with many serious anthropogenic problems including increased river bank erosion, water quality decline, increased flood risk and biodiversity loss. Conventional approaches to riparian restoration, however, are frequently too narrow in focus – spatially, temporally, ecologically and socially – to adequately or equitably address the goals to which they aspire. Climate change, along with the intensification of other human pressures, means that static, historically oriented restoration objectives focused solely on prior ecological composition and structure are unlikely to be defensible, achievable or appropriate in the Anthropocene. Conversely, open‐ended restoration strategies lacking clear objectives and targets entail substantial risks such as significant biodiversity losses, especially of native species. A functional approach to planning and prioritising riparian restoration interventions offers an intermediate alternative that is still framed by measurable targets but allows for greater consideration of broader temporal, spatial and cultural influences. Here, we provide an overview of major riparian functions across multiple scales and identify key drivers of, and threats to, these. We also discuss practical approaches to restoring and promoting riparian functions and highlight some key concerns for the development of policy and management of robust riparian restoration in the Anthropocene.     

Fish species diversity among spatial scales of altered temperate rivers

Aim The alteration of flowing systems over the past century has led to significant changes to the processes that drive these complex environments as well as to the scales at which these processes act. Recently, efforts have begun in earnest to restore some semblance of ecosystem diversity, but there is little understanding of exactly on what spatial scale or scales biotic diversity is responding. We investigated the manner in which fish diversity is partitioned at multiple spatial scales in two rivers in the central United States. Location The Missouri and Illinois rivers of the central United States. Methods We analysed how fish diversity was partitioned within the Illinois River and Missouri River systems by sampling each river under hierarchical frameworks that allowed analysis at section (large), reach (intermediate), and site (small) scales. We tested the hypothesis that there are scale‐dependent responses of fish diversity using an additive partitioning approach. Results Site alpha diversity was significantly higher than expected in both the Illinois and Missouri rivers. The relative contribution of alpha diversity to total diversity at a given spatial scale increased for the Illinois River, but not for the Missouri River, in that the highest alpha diversity contribution peaked at the reach scale. Diversity patterns from both rivers suggest that diversity at the site scale plays a significant role in determining the overall diversity in these systems. However, there is a substantial contribution at larger scales that warrants consideration when attempts are being made to protect or restore diversity and other ecosystem parameters. Main conclusions Understanding the variation of diversity in riverine systems is crucial for providing insight not only into how biotic communities respond to scale‐dependent factors, but also into the underlying abiotic and biotic factors that generate patterns of diversity across scales. These insights, in turn, are important for ensuring that restoration and management activities are targeting the appropriate scales for remediation. A lack of understanding of this issue could have negative outcomes for the recovery of a community in a restoration scenario, as well as resulting in a low economic return on restoration investments, which could hinder future efforts.     

The spatial scale of homogenisation and differentiation in Chihuahuan Desert fish assemblages

相似文献   

Developing fish community based ecohydrological indicators for water resources management in Taiwan

With concerns about the maintenance of both aquatic communities and flow conditions, a number of hydrologic indicators have been developed. These indicators are generally based on the development of hydrologic statistics for flows that are important to the maintenance of aquatic ecosystems. Although the hydrologic basis for indicators is well defined by common techniques in stochastic hydrology, the basis for ecological integration is still being developed. A critical evaluation of hydrologic indicators intended to protect aquatic ecosystems finds that proposed indicators are based more on standard hydrologic statistics and measures of hydrologic alteration than the habitat needs and ecological requirements of local or desired aquatic communities. We argue that hydrologic indicators are not ecohydrological indicators unless direct connections between flow events and aquatic community habitat and ecological needs are the basis of the indicator development and selection. In this article, we identify ecohydrological indicators that are based on habitat and ecological needs of fish communities. The indicator identification process is initiated with the analysis of community needs using an autecology matrix. Hydrologic statistics are then selected that are appropriate to the target fish community. The resulting ecohydrological indicators provide a direct connection to fish community flow requirements and the physical habitat conditions and associated ecology and life history needs of fish species. Handling editor: J. A. Cambray     

时空信息熵在延河流域生态可持续性分析中的应用

视流域为一个有生命力的不可分割的有机整体,为表征其生态可持续性,从熵的视角出发,提出结合空间信息熵和时间信息熵的时空信息熵方法。其中空间信息熵用于表征生态系统格局在空间分布的有序程度,时间信息熵用于度量生态系统的动态演变是否有序,时空信息熵方法将格局和动态有机结合,定量分析流域生态系统的可持续性。以延河流域为研究区,基于土地利用数据和归一化植被指数数据,利用时空信息熵方法分析2000-2018年延河流域生态可持续性。结果表明:(1)延河流域生态系统格局朝着有序的方向变化,此间整体处于生长期或恢复期;(2)时间信息熵结果呈现空间异质性,耕地、中低覆盖度草地和其他林地的时间信息熵值较高,生态弹性能力更强;(3)研究区生态可持续性以"强"和"较强"为主(61%),广泛分布在其中部和北部地区,表明流域的生态弹性能力总体增强,生态可持续状况明显改善。对基于熵视角研究生态可持续问题的有益探索,为延河流域及黄土高原其他类似流域的生态保护和修复提供借鉴和参考。     

Interactive effects of multiple stressors and restoration priorities in a mined Appalachian watershed

We surveyed benthic macroinvertebrate communities, water chemistry, and thermal regime in the Cheat River, WV, USA in an attempt to quantify the interactive effects of multiple stressors on ecological condition and identify priorities for restoration in this mined Appalachian watershed. We used a novel approach, which combined use of the West Virginia Stream Condition Index (WVSCI) to quantify ecological losses and community similarity analysis to assign specific levels of ecological loss to AMD, thermal effluent, and their interaction. Finally, we developed an ecological currency to quantify the relative benefits of a restoration program that focused either on AMD remediation or heat reduction and to identify spatially explicit restoration priorities. Variation in ecological condition was strongly correlated to variation in water quality when AMD and heat stress occurred in isolation. Acute inputs of AMD or heat caused predictable reductions in condition followed by rapid recovery downstream. However, benthic communities failed to recover from combined inputs of heat and AMD even when these stressors occurred at relatively low levels. Over the course of an entire year, AMD alone was over two times more responsible than heat alone for ecological loss. Consequently, AMD is the dominant factor limiting ecological condition and should be the primary target for restoration. Nevertheless, an AMD × heat interaction also was responsible for extensive ecological loss in lower reaches of the river. Consequently, full restoration of the lower Cheat River mainstem will require an approach that integrates AMD remediation with effective management of thermal effluent. Our results provide some of the first field evidence of the interactive effects of multiple stressors on biological communities in a mined watershed. This approach may be valuable for quantifying impacts from multiple interacting stressors and for prioritizing restoration efforts in other mined watersheds. Handling editor: S. M. Adams     

Understanding ecological change across large spatial,temporal and taxonomic scales: integrating data and methods in light of theory

The difficulty of integrating multiple theories, data and methods has slowed progress towards making unified inferences of ecological change generalizable across large spatial, temporal and taxonomic scales. However, recent progress towards a theoretical synthesis now provides a guiding framework for organizing and integrating all primary data and methods for spatiotemporal assemblage‐level inference in ecology. In this paper, we describe how recent theoretical developments can provide an organizing paradigm for linking advances in data collection and methodological frameworks across disparate ecological sub‐disciplines and across large spatial and temporal scales. First, we summarize the set of fundamental processes that determine change in multispecies assemblages across spatial and temporal scales by reviewing recent theoretical syntheses of community ecology. Second, we review recent advances in data and methods across the main sub‐disciplines concerned with ecological inference across large spatial, temporal and taxonomic scales, and organize them based on the primary fundamental processes they include, rather than the spatiotemporal scale of their inferences. Finally, we highlight how iteratively focusing on only one fundamental process at a time, but combining all relevant spatiotemporal data and methods, may reduce the conceptual challenges to integration among ecological sub‐disciplines. Moreover, we discuss a number of avenues for decreasing the practical barriers to integration among data and methods. We aim to reconcile the recent convergence of decades of thinking in community ecology and macroecology theory with the rapid progress in spatiotemporal approaches for assemblage‐level inference, at a time where a robust understanding of spatiotemporal change in ecological assemblages is more crucial than ever to conserve biodiversity.     

Response of marine communities to local temperature changes

As global climate change and variability drive shifts in species’ distributions, ecological communities are being reorganized. One approach to understand community change in response to climate change has been to characterize communities by a collective thermal preference, or community temperature index (CTI), and then to compare changes in CTI with changes in temperature. However, important questions remain about whether and how responsive communities are to changes in their local thermal environments. We used CTI to analyze changes in 160 marine assemblages (fish and invertebrates) across the rapidly‐changing Northeast U.S. Continental Shelf Large Marine Ecosystem and calculated expected community change based on historical relationships between species presence and temperature from a separate training dataset. We then compared interannual and long‐term temperature changes with expected community responses and observed community responses over both temporal scales. For these marine communities, we found that community composition as well as composition changes through time could be explained by species associations with bottom temperature. Individual species had non‐linear responses to changes in temperature, and these nonlinearities scaled up to a nonlinear relationship between CTI and temperature. On average, CTI increased by 0.36°C (95% CI: 0.34–0.38°C) for every 1°C increase in bottom temperature, but the relationship between CTI and temperature also depended on community composition. In addition, communities responded more strongly to interannual variation than to long‐term trends in temperature. We recommend that future research into climate‐driven community change accounts for nonlinear responses and examines ecological responses across a range of temporal and geographical scales.     

晋西黄土高原丘陵沟壑区清水河流域径流对土地利用与气候变化的响应

水资源短缺是黄土高原面临的最为关键的一个生态环境问题。研究黄土高原地区河川径流演变对土地利用与气候变化的响应是开展适应性流域管理的基础。该文以黄河流域中游山西省吉县境内的清水河流域(面积436 km²)为研究对象, 采用非参数统计秩检验法(Mann-Kendall)、滑动t检验和跃变参数分析法, 对该流域1959-2005年的年径流量、降水量和潜在蒸发散量进行了趋势分析和突变点验证; 用遥感数据判读和解译的结果分析了该流域不同时期土地利用变化; 在此基础上根据水量平衡原理, 分析了土地利用变化和气候变化对流域径流变化的贡献, 并采用FDC曲线法分析了二者对高、中、低流量变化的影响。研究结果表明: 该流域年径流量在1959-2005年的47年间呈显著下降趋势, 突变点出现在1980年, 但该流域降水量没有出现明显的趋势性变化, 而以Hamon公式计算的流域年潜在蒸发散则呈显著上升趋势, 其突变点出现在1997年。该流域气候变化和土地利用变化对年径流减少的贡献率分别为46.79%和53.21%。综合以上结果可以看出, 潜在蒸发散增加和乔木林地面积增加是导致该流域径流减少的重要原因。     

基于生态系统多维特征的粤港澳大湾区国土空间生态保护修复分区研究

我国国土空间生态保护修复已进入“山水林田湖草”系统治理和建设阶段。开展生态保护修复的分区研究,正确认识生态系统的地域组合特征及其分异规律,可以为落实系统治理理念提供空间指导。当前生态保护修复分区研究逐渐重视生态系统的完整性,但对于生态系统表征维度相对单一,导致对国土空间系统性综合认知受限。基于此,基于生态安全理论以及生态系统综合评估框架,构建生态保护修复分区的多维度指标体系,以提升对国土空间的系统性综合认知。以流域为基本单元,在评估粤港澳大湾区生态现状本底和退化特征的基础上,采用空间聚类方法划分两级生态保护修复分区。结果表明：(1)各流域生态现状质量和退化程度空间分异较为明显。生态现状质量呈现出外部高、中部低的圈层式分异特征。而生态退化空间分布则相对分散。(2)以生态现状综合指数与一级分区指标数据的空间异质性为基础,可将研究区划分为5个在空间上连续的生态保护修复一级区。以生态退化综合指数与二级分区指标数据的空间异质性为基础,可在一级区内部划分出11类29个生态保护修复二级区。研究方案可为国土空间的“山水林田湖草”系统治理提供生态分区优化路径。同时也为研究区生态保护修复提供了空间决策支持...     

基于景观格局的甘肃白龙江流域生态风险评价与管理

流域生态风险评价是流域生态保护与环境管理的重要研究内容.开展以人类活动为风险源的生态风险评价,揭示流域生态风险的空间变化规律,对于促进流域生态保护和环境管理及社会发展具有重要的指导意义.本文基于景观格局指数和生态环境脆弱度构建了流域生态风险综合指数,以甘肃白龙江流域2010年土地利用数据为基础,以ArcGIS和Fragstats软件为平台,通过空间采样和地统计空间插值得到白龙江流域生态风险的空间分布规律.结果表明：白龙江流域生态风险空间分布差异明显,总体而言,白龙江流域西北部和北部的生态风险高于流域的西部和南部山区;在白龙江流域各县区中,武都和宕昌县的生态风险较高,迭部县和文县的生态风险较低.今后应加强流域土地利用综合管理和人类活动调控,开展植被恢复和生态重建,降低不合理人为干扰的生态风险和危害,实现流域经济、社会与生态保护的“多赢”,促进区域可持续发展.     

黄土高原植被建设与土壤干燥化:问题与展望

黄土高原大规模植被建设有效减少了水土流失、改善了区域生态环境,大规模人工植被种植也造成了土壤水分的过度消耗,导致了土壤干燥化,成为当前黄土高原生态恢复的重要制约因素,威胁区域生态系统健康与稳定。系统综述了黄土高原地区人工植被恢复对土壤干燥化的作用机制,植被群落特征与土壤干燥化的耦合关系,多尺度土壤干燥化时空分异规律及其影响因素,明确了当前大规模人工植被恢复过程中土壤水分持续利用面临的问题与挑战。建议今后加强植被动态对水文过程影响的研究,明确多尺度植被格局与土壤干燥化时空分异的耦合关系,系统开展变化环境下不同尺度植被与土壤水分相互作用的模拟研究,探讨基于植被格局优化的土壤水分调控机制,维护黄土高原地区土壤安全,提升区域生态系统服务功能。     

Hierarchical Dynamics of Ecological Communities: Do Scales of Space and Time Match?

Theory posits that community dynamics organize at distinct hierarchical scales of space and time, and that the spatial and temporal patterns at each scale are commensurate. Here we use time series modeling to investigate fluctuation frequencies of species groups within invertebrate metacommunities in 26 boreal lakes over a 20-year period, and variance partitioning analysis to study whether species groups with different fluctuation patterns show spatial signals that are commensurate with the scale-specific fluctuation patterns identified. We identified two groups of invertebrates representing hierarchically organized temporal dynamics: one species group showed temporal variability at decadal scales (slow patterns of change), whilst another group showed fluctuations at 3 to 5-year intervals (faster change). This pattern was consistently found across all lakes studied. A spatial signal was evident in the slow but not faster-changing species groups. As expected, the spatial signal for the slow-changing group coincided with broad-scale spatial patterns that could be explained with historical biogeography (ecoregion delineation, and dispersal limitation assessed through a dispersal trait analysis). In addition to spatial factors, the slow-changing groups correlated with environmental variables, supporting the conjecture that boreal lakes are undergoing environmental change. Taken together our results suggest that regionally distinct sets of taxa, separated by biogeographical boundaries, responded similarly to broad-scale environmental change. Not only does our approach allow testing theory about hierarchically structured space-time patterns; more generally, it allows assessing the relative role of the ability of communities to track environmental change and dispersal constraints limiting community structure and biodiversity at macroecological scales.     

The influence of watershed land use cover on stream fish diversity and size-at-age of a generalist fish

Changes in land use have manifold effects on stream ecosystems. Consequently, the degradation of watersheds can cause extreme responses if the resilience of the stream is exceeded, triggering changes in fish communities and a reorganization of the ecosystem. Fish community surveys are frequently used to evaluate the impact of anthropogenic pressures on freshwater streams. Dynamic indices such as individual growth are also interesting because they integrate the effects of environmental conditions through time, providing an assessment in the long term. In this study we have investigated the ecological implications of watershed land use cover on fish diversity and growth of the generalist species Umbra limi (central mudminnow) in six streams in Southern Ontario (Canada). In detail, the growth of U. limi has been explored using a Dynamic Energy Budget (DEB) model, which pursues a mechanistic explanation of the bioenergetics of an individual under different environmental conditions. Given the mechanistic approach, the outcomes of the DEB model can provide a solid foundation for extrapolating the conclusions of this study to a broader spatial scale. The results of this study reveal that the proportion of modified land use of the watershed (agricultural and urban land) can reach a tipping point beyond which the functioning of the stream abruptly changes. Consequently, land use cover may be used as a precautionary indicator for watershed management. The results also demonstrate that U. limi could be used as a sentinel species to identify potential impacts on fish diversity and size-at-age as a cost-effective indicator for stream monitoring programs.     

The Disconnect Between Restoration Goals and Practices: A Case Study of Watershed Restoration in the Russian River Basin, California

Over the past two decades, watershed restoration has dramatically increased internationally. California has been at the forefront, allocating billions of dollars to restoration activities through legislation and voter-approved bonds. Yet, the implications of restoration remain ambiguous because there has been little examination of restoration accomplishments and almost no analysis of the political context of restoration. This article addresses these gaps, utilizing a case study of the Russian River basin in Northern California. We identify trends that shed light on both the ecological and the political implications of restoration at a basin scale by examining a database of 787 restoration projects implemented in the Russian River basin since the early 1980s. Although a total of over $47 million has been spent on restoration in the basin, dominant forms of restoration are limited in scope to small-scale projects that focus on technical solutions to site-specific problems. The majority of restoration efforts are devoted to road repair, riparian stabilization, and in-stream structures, accounting for 62% of all projects. These types of projects do not address the broader social drivers of watershed change such as land and water uses. We suggest that restoration can become more effective by addressing the entire watershed as a combination of social and ecological forces that interact to produce watershed conditions.