Improving ecological response monitoring of environmental flows

Monitoring for the adaptive management of rivers

Monitoring for adaptive management (AM) involves collection of data with the aim of reducing uncertainty about links between human pressures (e.g. water abstraction from rivers), consequent stressors (e.g. low river flows) and environmental state (e.g. biodiversity). 'Surveillance monitoring' involves documenting trends in state, without the aim of understanding relationships between state, stressors, and pressures. Critics have highlighted that surveillance monitoring dominates monitoring investments but is not supporting AM. Decision-makers continue to be disappointed by monitoring data that are unsuitable for AM, yet designers of monitoring programs tend to make decisions that reinforce rather than reimagine the status quo. We argue that a structured, collaborative approach to objective-setting is required to break the status quo. We collaborated with regional management authorities to develop monitoring objectives and implementation strategies to support AM of New Zealand's rivers. Our collaborative approach discouraged 'failure fearing' and encouraged reimagining 'what could be' as opposed to 'what is.' Seventeen monitoring objectives were identified based on the AM requirements of national policy and regional authorities. Several objectives-particularly those arising from national policy-stretch the limits of what environmental science can currently provide. There were also strong trade-offs among objectives. We offer practical implementation strategies for overcoming the technical challenges of, and reducing trade-offs among, monitoring objectives. These strategies point to a monitoring program that contrasts strongly with one aimed at surveillance. Monitoring for AM is more complex than monitoring for surveillance, so strong leadership is required for successful implementation.

Transcriptome analysis of Chinese sucker (Myxocyprinus asiaticus) head kidney and discovery of key immune-related genes to cold stress after swimming fatigue

For Chinese sucker (Myxocyprinus asiaticus), passing through a dam with fast flow and cold water are always unavoidable, and this process can cause stress, disease or even death. In this study, comparative transcriptome analysis was conducted to investigate the potential immune mechanism in head kidney of M. asiaticus with swimming fatigue stress and cold stress after fatigue. In general, a total of 181,781 unigenes were generated, and 38,545 differentially expressed genes (DEGs) were identified. In these DEGs, 22,593, 7286 and 8666 DEGs were identified among groups of fatigue vs. cold, control vs. cold, and control vs. fatigue, respectively. Enrichment analysis revealed these DEGs were involved in coagulation cascades and complement, natural killer cell mediated cytotoxicity, antigen processing and presentation, Toll-like receptor signaling pathways, and chemokine signaling pathway. Notably, immune genes including heat shock protein 4a (HSP4a), HSP70 and HSP90α genes were significantly up-regulated in fishes with cold stress after fatigue. Differently, more immune genes in control vs. cold compared with that in control vs. fatigue were significantly down-regulated expression, such as claudin-15-like, Toll-like receptor 13, antimicrobial peptide (hepcidin), immunoglobulin, CXCR4 chemokine receptor, T-cell receptor, complement factor B/C2-A3, and interleukin 8. In this study, the number of DEGs in the head kidney was less than that our previous study in the spleen, which we speculated was more sensitive to changes in water temperature than the head kidney. In summary, lots of immune-related genes in the head kidney were down-regulated under cold stress after fatigue, suggesting that M. asiaticus might have experienced severe immunosuppression in the process of passing through the dam.

Applying Optimization to Support Adaptive Water Management of Rivers

Adaptive water management is a promising management paradigm for rivers that addresses the uncertainty of decision consequences. However, its implementation into current practice is still a challenge. An optimization assessment can be framed within the adaptive management cycle allowing the definition of environmental flows (e-flows) in a suitable format for decision making. In this study, we demonstrate its suitability to mediate the incorporation of e-flows into diversion management planning, fostering the realization of an adaptive management approach. We used the case study of the Pas River, Northern Spain, as the setting for the optimization of surface water diversion. We considered e-flow requirements for three key river biological groups to reflect conditions that promote ecological conservation. By drawing from hydrological scenarios (i.e., dry, normal, and wet), our assessment showed that the overall target water demand can be met, whereas the daily volume of water available for diversion was not constant throughout the year. These results suggest that current the decision making needs to consider the seasonal time frame as the reference temporal scale for objectives adjustment and monitoring. The approach can be transferred to other study areas and can inform decision makers that aim to engage with all the stages of the adaptive water management cycle.

Assessing Effects of Flow Regulation and an Experimental Flow Pulse on Population Size Structure of Riverine Fish with Contrasting Biological Characteristics

Despite effects of dams and water extraction on river hydrology and consequences of aquatic ecosystems being broadly appreciated, empirical evidence is lacking for many regions (e.g. subtropics). Evidence is necessary to determine (i) the circumstances where environmental flows are necessary to protect or improve ecological processes and (ii) what hydrological events are required to achieve those ecological characteristics. Here, temporal variation in the size structure of two small-bodied fish species with contrasting ecological characteristics (Australian smelt, Cox's gudgeon) was compared between two pairs of unregulated and regulated rivers in subtropical Australia. Frequency of in-channel flow pulses in each regulated river was lower compared to paired unregulated rivers. An experimental flow pulse was delivered to one regulated river to assess the ecological outcomes of in-channel flow pulses and inform future decisions about the use of environmental water allocations. Temporal changes in the population size structure of both species were similar between unregulated and regulated rivers and showed no response to the experimental pulse. While the experimental flow briefly suppressed in-stream temperature, changes in temperature were not beyond the thresholds at which spawning occurs or the thermal tolerances for either species. Similar population structure between unregulated and regulated rivers can be attributed to the magnitude of flow regulation being insufficient to alter the physico-chemical conditions, habitat and trophic mechanisms supporting population dynamics during the study period. This suggests current regulated hydrology is protective of local populations of Australian smelt and Cox's gudgeon in these study rivers.

Is there enough water? How bearish and bullish outlooks are linked to decision maker perspectives on environmental flows

Policies that mandate environmental flows (e-flows) can be powerful tools for freshwater conservation, but implementation of these policies faces many hurdles. To better understand these challenges, we explored two key questions: (1) What additional data are needed to implement e-flows? and (2) What are the major socio-political barriers to implementing e-flows? We surveyed water and natural resource decision makers in the semi-arid Red River basin, Texas-Oklahoma, USA, and used social network analysis to analyze their communication patterns. Most respondents agreed that e-flows can provide important benefits and identified the same data needs. However, respondents sharply in their beliefs on other issues, and a clustering analysis revealed two distinct groups of decision makers. One cluster of decision makers tended to be bearish, or pessimistic, and believed that: current flow conditions are not adequate, there are many serious socio-political barriers to implementation, water conflicts will likely increase in the future, and climate change is likely to exacerbate these issues. The other cluster of respondents was bullish, or optimistic: they foresaw fewer future water conflicts and fewer socio-political barriers to implementation. Despite these differences, both clusters largely identified the same data needs and barriers to e-flows implementation. Our social network analysis revealed that the frequency of communication between clusters was not significantly different than the frequency of communication within clusters. Overall, our results suggest that the different perspectives of decision-makers could complicate efforts to implement e-flows and proactively plan for climate change. However, there are opportunities for collaboration on addressing common data needs and barriers to implementation. Overall, our study provides a key socio-environmental perspective on e-flows implementation from a semi-arid and socio-politically complex river basin and contextualizes the many challenges facing e-flows implementation in river basins globally.

Assessing the Establishment and Implementation of Environmental Flows in Spain

The alteration of natural flows due to water withdrawals and the presence of hydraulic infrastructure poses significant threats to the integrity of riverine ecosystems. The establishment of environmental flows (EF) has been conceived as a water management tool to mitigate the impact of in-stream flows alteration. To date, a large body of literature has focused on methods to define EF, but less attention has been paid to documenting and assessing their actual implementation on the ground. This article provides a framework to describe and assess the process of design, application, and monitoring of EF at a river basin level. The framework is applied to Spain, where significant efforts have been made during the past decade to define and implement EF across the country. The goal of the paper is to identify strengths and opportunities for improving the implementation of EF at country level. The Spanish legislation establishes that EF should contribute to the achievement of the good ecological status of surface water bodies as required by the European Union Water Framework Directive. Several pitfalls in the design, application, and monitoring of this important river management measure constrain the ability of the existing EF to deliver that fundamental outcome.

Flow alteration-ecology relationships in Ozark Highland streams: Consequences for fish, crayfish and macroinvertebrate assemblages

We examined flow alteration-ecology relationships in benthic macroinvertebrate, fish, and crayfish assemblages in Ozark Highland streams, USA, over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013). We hypothesized that: 1) there would be temporal variation in flow alteration-ecology relationships between the two years, 2) flow alteration-ecology relationships would be stronger during the drought year vs the flood year, and 3) fish assemblages would show the strongest relationships with flow alteration. We used a quantitative richest-targeted habitat (RTH) method and a qualitative multi-habitat (QMH) method to collect macroinvertebrates at 16 USGS gaged sites during both years. We used backpack electrofishing to sample fish and crayfish at 17 sites in 2012 and 11 sites in 2013. We used redundancy analysis to relate biological response metrics, including richness, diversity, density, and community-based metrics, to flow alteration. We found temporal variation in flow alteration-ecology relationships for all taxa, and that relationships differed greatly between assemblages. We found relationships were stronger for macroinvertebrates during the drought year but not for other assemblages, and that fish assemblage relationships were not stronger than the invertebrate taxa. Magnitude of average flow, frequency of high flow, magnitude of high flow, and duration of high flow were the most important categories of flow alteration metrics across taxa. Alteration of high and average flows was more important than alteration of low flows. Of 32 important flow alteration metrics across years and assemblages, 19 were significantly altered relative to expected values. Ecological responses differed substantially between drought and flood years, and this is likely to be exacerbated with predicted climate change scenarios. Differences in flow alteration-ecology relationships among taxonomic groups and temporal variation in relationships illustrate that a complex suite of variables should be considered for effective conservation of stream communities related to flow alteration.

Environmental Flow Assessment Considering Inter- and Intra-Annual Streamflow Variability under the Context of Non-Stationarity

A key challenge to environmental flow assessment in many rivers is to evaluate how much of the discharge flow should be retained in the river in order to maintain the integrity and valued features of riverine ecosystems. With the increasing impact of climate change and human activities on riverine ecosystems, the natural flow regime paradigm in many rivers has become non-stationary conditions, which is a new challenge to the assessment of environmental flow. This study presents a useful framework to (1) detect change points in runoff time series using two statistical methods (Mann-Kendall test method and heuristic segmentation method), (2) adjust data of the changed period against the original flow series into a stationary condition using a procedure of reconstruction; and (3) incorporate inter- and intra-annual streamflow variability with adjusted streamflow to evaluate environmental flow. The Jialing to Han inter-basin water transfer project was selected as the case study. Results indicate that a change point of 1994 was identified, revealing that the stationarity of annual streamflow series is invalid. The variations of reconstructed streamflow series are roughly consistent with original streamflow series, especially in the maximum/minimum values and rise/fall rates, but the mean value of reconstructed streamflow series is increased. The reconstructed streamflow series would further serve to eliminate the non-stationary of original streamflow, and incorporating the inter- and intra-annual variability would upgrade the ecosystem fitness. Selecting different criteria for the conservation of riverine ecosystems can have significantly different consequences, and we should not focus on the protection of specific objectives that will inevitably affect other aspects. This study provides a useful framework for environmental flow assessment and can be applied to a wide range of instream flow management approaches to protect the riverine ecosystem.

Hydrologic Characteristics of Streamflow in the Southeast Atlantic and Gulf Coast Hydrologic Region during 1939–2016 and Conceptual Map of Potential Impacts

Streamflow is one the most important variables controlling and maintaining aquatic ecosystem integrity, diversity, and sustainability. This study identified and quantified changes in 34 hydrologic characteristics and parameters at 30 long term (1939–2016) discharge stations in the Southeast Atlantic and Gulf Coast Hydrologic Region (Region 3) using Indicators of Hydrologic Alteration (IHA) variables. The southeastern United States (SEUS) is a biodiversity hotspot, and the region has experienced a number of rapid land use/land cover changes with multiple primary drivers. Studies in the SEUS have been mostly localized on specific rivers, reservoir catchments and/or species, but the overall region has not been assessed for the long-term period of 1939–2016 for multiple hydrologic characteristic parameters. The objectives of the study were to provide an overview of multiple river basins and 31 hydrologic characteristic parameters of streamflow in Region 3 for a longer period and to develop a conceptual map of impacts of selected stressors and changes in hydrology and climate in the SEUS. A seven step procedure was used to accomplish these objectively: Step 1: Download data from the 30 USGS gauging stations. Steps 2 and 3: Select and analyze the 31 IHA parameters using boxplots, scatter plots, and PDFs. Steps 4 and 5: Synthesize the drivers of changes and alterations and the various change points in streamflow in the literature. Step 6: Synthesize the climate of the SEUS in terms of temperature and precipitation changes. Step 7: Develop a conceptual map of impacts of selected stressors on hydrology using Driver–Pressure–State-Impact–Response (DPSIR) framework and IHA parameters. The 31 IHA parameters were analyzed. The meta-analysis of literature in the SEUS revealed the precipitation changes observed ranged from −30% to +35% and temperature changes from −2 °C to 6 °C by 2099. The fiftieth percentile of the Global Climate Models (GCM) predict no precipitation change and an increase in the temperature of 2.5 °C in the region by 2099. Among the GCMs, the 5th and 95th percentile of precipitation changes range between −40% and 110% and temperature changes between −2 °C and 6 °C by 2099. Meta-analysis of land use/land cover show the region has experienced changes. A number of rapid land use/land cover changes in 1957, 1970, and 1998 are some of the change points documented in the literature for precipitation and streamflow in the region. A conceptual map was developed to represent the impacts of selected drivers and the changes in hydrology and climate in the study region for three land use/land cover categories in three different periods.

Predicting the Influence of Streamflow on Migration and Spawning of a Threatened Diadromous Fish, the Australian Grayling Prototroctes Maraena

The development of effective strategies to restore the biological functioning of aquatic ecosystems with altered flow regimes requires a detailed understanding of flow-ecology requirements, which is unfortunately lacking in many cases. By understanding the flow conditions required to initiate critical life history events such as migration and spawning, it is possible to mitigate the threats posed by regulated river flow by providing targeted environmental flow releases from impoundments. In this study, we examined the influence of hydrological variables (e.g., flow magnitude), temporal variables (e.g., day of year) and spatial variables (e.g., longitudinal position of fish) on two key life history events (migration to spawning grounds and spawning activity) for a threatened diadromous fish (Australian grayling Prototroctes maraena) using data collected from 2008 to 2015 in the Bunyip-Tarago river system in Victoria. Our analyses revealed that flow changes act as a cue to downstream migration, but movement responses differed spatially: fish in the upper catchment showed a more specific requirement for rising discharge to initiate migration than fish in the lower catchment. Egg concentrations peaked in May when weekly flows increased relative to the median flow during a given spawning period. This information has recently been incorporated into the development of targeted environmental flows to facilitate migration and spawning by Australian grayling in the Bunyip-Tarago river system and other coastal systems in Victoria.

Benthic macroinvertebrates response to water management in a lowland river: effects of hydro-power vs irrigation off-stream diversions

An eco-hydraulic survey of the highly regulated Adda River (northern Italy) was carried out to highlight the ecological implications of the current water management, including minimum flows (MFs) set as environmental protection measures. Macroinvertebrates, flows, and other main physico-chemical parameters were monitored from 2010 to 2012 at seven sites located in two river reaches characterized by different water abstraction schemes. In the upper part of the river, water is mainly diverted for hydro-power, and, in water-depleted reaches, discharges equalled MF for more than 100 days y^-1, mainly during winter. In the downstream river reach, where irrigation use prevails, discharges were on average three times higher than in the upper part of the river, and flow values similar to MF were detected only for short periods during summer. The two resulting streamflow patterns seem to have shaped different benthic communities, superimposing to the natural downstream variation. The upper reach is characterized by univoltine taxa, while the lower reach by multivoltine taxa adapted to a more disturbed environment. Chironomidae, a well-known tolerant benthic family, dominated at a site affected by point-source pollution, which turned out to be another determinant of macroinvertebrate community. Despite these differences among sites in the benthic community structure, the current water management seems to allow, for all of the investigated river sites, the achievement of the good ecological status as defined by the local law set in accomplishment of the Water Framework Directive.

A framework for evaluating food-web responses to hydrological manipulations in riverine systems

Environmental flows are used to restore elements of the hydrological regime altered by human use of water. One of the primary justifications and purposes for environmental flows is the maintenance of target species populations but, paradoxically, there has been little emphasis on incorporating the food-web and trophic dynamics that determine population-level responses into the monitoring and evaluation of environmental flow programs. We develop a generic framework for incorporating trophic dynamics into monitoring programs to identify the food-web linkages between hydrological regimes and population-level objectives of environmental flows. These linkages form the basis for objective setting, ecological targets and indicator selection that are necessary for planning monitoring programs with a rigorous scientific basis. Because there are multiple facets of trophic dynamics that influence energy production and transfer through food webs, the specific objectives of environmental flows need to be defined during the development of monitoring programs. A multitude of analytical methods exist that each quantify distinct aspects of food webs (e.g. energy production, prey selection, energy assimilation), but no single method can provide a basis for holistic understanding of food webs. Our paper critiques a range of analytical methods for quantifying attributes of food webs to inform the setting, monitoring and evaluation of trophic outcomes of environmental flows and advance the conceptual understanding of trophic dynamics in river-floodplain systems.

Creating institutional flexibility for adaptive water management: insights from two management agencies

Adaptive management is an experimental approach used by water management agencies around the world to manage and restore aquatic ecosystems. The effectiveness of the approach can often be constrained by inflexible institutional arrangements. In this paper we compare two cases where agencies have implemented adaptive management to manage and restore aquatic ecosystems. Our aim was to understand practitioners' perceptions of how institutional flexibility can be created for adaptive management. We interviewed 14 adaptive management practitioners working in the Murray-Darling Basin, Australia and 14 practitioners in Southern Florida, United States of America. We found that in both cases, just enough flexibility was created to enable experimentation, but informal institutional arrangements tended to constrain adaptive management. We also found that adaptive management was effective when an agency adopted collaborative and distributed leadership, but these leadership styles were difficult to sustain, and not always appropriate when attempting to create institutional flexibility. Our results illustrate how agencies, stakeholders and researchers can develop a shared understanding of how to manage and restore aquatic ecosystems, which in turn, helps create institutional flexibility for an agency to manage adaptively.

Assessment of the natural flow regime in a Mediterranean river impacted from irrigated agriculture

Over the last few decades, the natural flow regime of most rivers has been significantly altered influencing the ecological integrity and functioning of river ecosystems. Especially in the Mediterranean region, irrigated agriculture is considered one of the most important drivers of hydro-morphological modifications in river systems. In this study we employ the Indicators of Hydrologic Alteration (IHA) methodology for the Pinios River and its tributaries, located in a Mediterranean catchment in central Greece, with the purpose to assess the natural flow regime under a simulated no-agriculture scenario and compare with the current situation. The work is based on the use of the SWAT (Soil Water Assessment Tool) model for the simulation of long time series of daily stream flows, which were analyzed under the actual conditions (baseline), and the hypothetical scenario. The key characteristics of the flow regime projected under each model run were assessed through the implementation of the IHA methodology that utilizes a number of indicators to characterize the intra- and inter-annual variability in the hydrologic conditions. The results of this study revealed that without agricultural activities in the catchment, annual and monthly flows would increase, with significant alterations in the flow characteristics of the winter months, and much smaller in summer. However, the analysis showed that the frequency of droughts and low flow summer events would be smaller. The article provides a comprehensive and easy-to-implement methodology that can facilitate the impact assessment of agricultural human activities on river flow variability under the typical Mediterranean conditions, allowing experimentation on setting river flow thresholds required for a good ecological status within the context of the European Water Framework Directive.