Cherie J. Westbrook

An approach for assessing cumulative effects in a model river, the Athabasca River basin

Novel approaches addressing aquatic cumulative effects over broad temporal and spatial scales are required to track changes and assist with sustainable watershed management. Cumulative effects assessment (CEA) requires the assessment of changes due to multiple stressors both spatially and temporally. The province of Alberta, Canada, is currently experiencing significant economic growth as well as increasing awareness of water dependencies. There has been an increasing level of industrial, urban, and other land-use related development (pulp and paper mills, oil sands developments, agriculture, and urban development) within the Athabasca River basin. Much of the historical water quantity and quality data for this basin have not been integrated or analyzed from headwaters to mouth, which affects development of a holistic, watershed-scale CEA. The main objectives of this study were 1) to quantify spatial and temporal changes in water quantity and quality over the entire Athabasca River mainstem across historical (1966–1976) and current day (1996–2006) time periods and 2) to evaluate the significance of any changes relative to existing benchmarks (e.g., water quality guidelines). Data were collected from several federal, provincial, and nongovernment sources. A 14% to 30% decrease in discharge was observed during the low flow period in the second time period in the lower 3 river reaches with the greatest decrease occurring at the mouth of the river. Dissolved Na, sulfate, chloride, and total P concentrations in the second time period were greater than, and in some cases double, the 90th percentiles calculated from the first time period in the lower part of the river. Our results show that significant changes have occurred in both water quantity and quality between the historical and current day Athabasca River basin. It is known that, in addition to climatic changes, rivers which undergo increased agricultural, urban, and industrial development can experience significant changes in water quantity and quality due to increased water use, discharge of effluents, and surface run-off. Using the results from this study, we can begin to quantify dominant natural and man-made stressors affecting the Athabasca River basin as well as place the magnitude of any local changes into an appropriate context relative to trends in temporal and spatial variability.

Assessing large spatial scale landscape change effects on water quality and quantity response in the lower Athabasca River basin.

Increased land use intensity has been shown to adversely affect aquatic ecosystems. Multiple landscape stressors interact over space and time, producing cumulative effects. Cumulative Effects Assessment (CEA) is the process of evaluating the impact a development project may have on the ecological surroundings, but several challenges exist that make current approaches to cumulative effects assessment ineffective. The main objective of this study was to compare results of different methods used to link landscape stressors with stream responses in a highly developed watershed, where past work has shown that the river has experienced significant water quality and quantity changes to improve approaches to CEA. The study site was the lower reaches of the Athabasca River, Canada that have been subjected to a diverse range of intense anthropogenic developments since the late 1960s. Linkages between landscape change and river response were evaluated using correlation analyses, stepwise, multiple regression, and regression trees. Notable landscape changes include increased industrial development and forest cut-blocks, made evident from satellite imagery and supporting ancillary data sets. Simple regression analyses showed water use was closely associated with total phosphorus (TP) and Na(+) concentrations, as well as specific conductance. The regression trees for total organic carbon (TOC), TP, and Na(+) showed that the landscape variables that appear as the first characteristic were the same variables that showed significant relations for their respective simple regression models. Simple, stepwise, and multiple regressions in conjunction with regression trees were useful in this study for capturing the strongest associations between landscape stressors and river response variables. The results highlight the need for improved scaling methods and monitoring strategies crucial to managing cumulative effects to river systems.

Science requisites for cumulative effects assessment for wetlands

Wetland habitat continues to be lost to cumulative effects of development on the landscape. Part of the problem is that there currently exists only limited guidance as to how to use the existing scientific tools, conceptual frameworks and guidance documents to advance cumulative effects assessment (CEA) from the project scale to the broader regional scale at which land-use planning occurs. To strengthen CEA science for wetlands there are three minimum requirements: (1) understand the baseline science of wetland functions; (2) delineate the primary drivers (anthropogenic and natural) of disturbance; and (3) develop the science to link drivers to changes in wetland function in an interactive, synergistic and cumulative way. The paper concludes by identifying ways in which the state of CEA science and management of wetlands could be improved.

Alteration of hydrogeomorphic processes by invasive beavers in southern South America.

The North American beaver (Castor canadensis) is an invasive species in southern Patagonia, introduced in 1946 as part of a program by the Argentine government to augment furbearers. Research focus has turned from inventorying the beavers population and ecosystem impacts toward eradicating it from the region and restoring degraded areas. Successful restoration, however, requires a fuller determination of how beavers have altered physical landscape characteristics, and of what landscape features and biota need to be restored. Our goal was to identify changes to the physical landscape by invasive beaver. We analyzed channel and valley morphology in detail at one site in each of the three major forest zones occurring on the Argentine side of Tierra del Fuegos main island. We also assessed 48 additional sites across the three forest biomes on the island to identify a broader range of aquatic habitat occupied and modified by beaver. Beaver build dams with Nothofagus tree branches on streams, which triggered mineral sediment accretion processes in the riparian zone, but not in ways consistent with the beaver meadow theory and only at a few sites. At the majority of sites, beavers actively excavated peat and mineral sediment, moved thousands of cubic meters of sediment within their occupied landscapes and used it to build dams. Beaver were also common in fen ecosystems where pond formation inundated and drowned peat forming mosses and sedges, and triggered a massive invasion of exotic plant species. Results highlight that restoration of fen ecosystems is a previously unrecognized but pressing and challenging restoration need in addition to reforestation of Nothofagus riparian forests. We recommend that decision-makers include the full ecosystem diversity of the Fuegian landscape in their beaver eradiation and ecosystem restoration plans.

A Review of the Flood Risk Management Governance and Resilience Literature

The environmental management literature suggests that resilience is key to managing complex systems and reducing vulnerability resulting from uncertainty and unexpected change. Yet, flood risk management (FRM) has emerged largely from a culture of resistance. This paper takes the pulse of the current state of FRM research, with a focus on how the scholarly community has approached governance for flood resilience. Our analysis of the FRM journal literature identified 258 articles addressing governance and flooding, resilience and adaptation. Five main research themes emerged from these articles, addressing a variety of issues, but mostly lacking the degree of integration needed to address the social-ecological complexity of FRM. Overall, research supporting the governance of FRM for resilience lacks integration, and methods of mitigating this lack of integration are poorly studied. We conclude with a discussion about the nature and scope of FRM research for resilience, and identify opportunities for more integrative FRM research that is more tightly coupled with policy and practice.

Effects of in‐channel beaver impoundments on mercury bioaccumulation in Rocky Mountain stream food webs

Beavers (Castor spp.) are ecosystem engineers and important modifiers of freshwater ecosystems. They create impoundments that flood the surrounding landscape and modify the flow of materials through streams, thus potentially increasing nutrients, productivity and the availability of toxic methyl mercury (MeHg) to downstream food webs. Here we quantify food web-available MeHg in water, periphyton, and invertebrates collected from 15 streams up- and down-stream from beaver impoundments in the Rocky Mountain foothills of Western Canada. While nutrients, algal biomass, and total invertebrate standing stock were not significantly elevated below ponds, MeHg concentrations (average increase of 1.7×) and percent of total Hg that was MeHg (average increase of 1.3×) showed a trend of higher values in all compartments downstream and the difference was significant in predatory invertebrates. This suggests that beaver impoundments can increase the availability and subsequent uptake of MeHg by basal food web organisms even if their immediate influence on nutrients and resources is limited. As beaver populations continue to rebound, more research is needed to fully characterise the effects of beavers on nutrient and contaminant cycling under different biogeochemical conditions.

Wetlands of the Hudson Bay Lowland: An Ontario Overview

Riley’s Wetlands of the Hudson Bay Lowland: An Ontario Overview is a comprehensive catalogue of the ecological variation across one of the largest wetland complexes in the world. Undertaking a regional assessment of wetland variation that includes insight into the environmental factors regulating the variation is a formidable task, considering the remoteness, inaccessibility and harsh working conditions of the Hudson Bay Lowland. This compilation of 30 years of field data is not only essential, but timely, given that there are new resource developments (Whittington and Price 2013) and rapidly changing climate conditions (Rühland et al. 2013) in the Lowland. The book is divided into five main sections that build off of one another, which are followed by a chapter outlining a wetland classification scheme for the region, and several data archives. The “Regional Overview” chapter does an excellent job of contextualizing the major habitats, geology and climate of the Lowland. It goes further to describe the global importance of the region as a carbon store, albeit using mostly older references, and speculates on how climate warming could impact the ecological functioning of wetlands in the region. The “Regional Wetland Variability” chapter first defines the term “wetland” and then describes the history of its classification, which is important because of the changing approach to classification over the time in which the field data were collected. The chapter ends with a useful description of the six main wetland formations that occur in the region. It was thoughtful to add a tidbit on the origin of the names given to each formation, and a field key (Appendix A). The “Sampling Methods” chapter documents, with transparency, how and where field data were collected. Included was an example of the data collection sheets used, and a wonderful map (Fig. 5) that depicts the location of all wetlands visited over the 18 years of field work. Although summary data from each sampled wetland are given in Appendix C, making it an important catalogue, it would have been helpful to also include their approximate geographic location. Summary data from all sampled wetlands are presented in the “Environmental Variability” chapter. Variations in plant communities that occur across the Lowland are depicted with multivariate ordinations, and are related to environmental variables. The types of analyses presented are simple, yet effective for showing broadscale patterns. The provision of key indicator plant species for the different wetland formations should prove handy to those conducting future work in the region. The chapter was not overly technical, and is thus appropriate for an environmental assessment and land use planning audience. Researchers should also be able to use these data, as scientific names of all plant species are provided. The first four chapters culminate in one entitled “Wetland Succession,” which provides a broad-scale description of both temporal and lateral wetland succession of the Lowland. The strength of this chapter is that it offers a hypothesis of how the region is likely to evolve as it continues to grow in areal extent as it isostatically rebounds. Throughout the book, there are numerous colour photographs, which not only enhance its appeal but are critical in helping the reader visualize the complexity and remoteness of the landscape. There are, however, a few things missing from the book that would have been nice to see. For example, most of the work cited was completed more than a decade ago, despite there being a flurry of research activity in the region in the last few years. Also, I found it a bit odd that scientific names were used for plant species, but that wildlife are referred to exclusively by their common names. Overall, though, the Wetlands of the Hudson Bay Lowland: An Ontario Overview is an excellent sourcebook for anyone looking for natural resource knowledge of the Hudson Bay Lowland. It is a valuable manual that provides essential information that should be used to support sound environmental assessments and informed land use planning decisions in the North.

A modelling framework to simulate field-scale nitrate release and transport during snowmelt: the WINTRA model

Modeling nutrient transport during snowmelt in cold regions remains a major scientific challenge. A key limitation of existing nutrient models for application in cold regions is the inadequate representation of snowmelt, including hydrological and biogeochemical processes. This brief period can account for more than 80% of the total annual surface runoff in the Canadian Prairies and Northern Canada and processes such as atmospheric deposition, over-winter redistribution of snow, ion exclusion from snow crystals, frozen soils, and snowcovered area depletion during melt influence the distribution and release of snow and soil nutrients, thus affecting the timing and magnitude of snowmelt runoff nutrient concentrations. Research in cold regions suggests that nitrate (NO3) runoff at the field scale can be divided into five phases during snowmelt. In the first phase, water and ions originating from ion-rich snow layers travel and diffuse through the snowpack. This process causes ion concentrations in runoff to gradually increase. The second phase occurs when this snow ion meltwater front has reached the bottom of the snowpack and forms runoff to the edge-of-the-field (EOF). During the third and fourth phases, the main source of NO3 transitions from the snowpack to the soil. Finally, the fifth and last phase occurs when the snow has completely melted, and the thawing soil becomes the main source of NO3 to the stream. In this research, a process-based model was developed to simulate hourly export based on this five-phase approach. Results from an application in the Red River Basin of southern Manitoba, Canada shows that the model can adequately capture the dynamics and rapid changes of NO3 concentrations during this period at relevant temporal resolutions. This is a significant achievement to advance the current nutrient modeling paradigm in cold climates, which is generally limited to satisfactory results at monthly or annual resolutions. The approach can inform catchment-scale nutrient models to improve simulation of this critical snowmelt period. Nutrient exports Winter Snow Nitrate Agriculture Nutrient model

Beaver-mediated water table dynamics in a Rocky Mountain fen

Beaver dams are known to raise water tables in mineral soil environments but very little is known about their impact in wetlands, such as peatlands. Peatlands tend to have shallow water tables, and the position and tendency of the water table to fluctuate (i.e. stability) is a factor controlling the systems ability to store carbon and water. Many peatland environments, especially fens, offer ideal habitat for beaver and the potential for beaver dams to influence this link by manipulating water table dynamics requires investigation. Our objective was to determine the influence of beaver dams on water table dynamics of a Rocky Mountain fen. We monitored water tables in the peatland for four years while beaver dams were intact and two years after they were breached by an extreme flood event. We found that, because of the unique way in which dams were built, they connected the peatland to the stream and raised and stabilized already high water tables within a 150-m radius. Beaver-mediated changes to peatland water table regimes have the potential to enhance carbon sequestration and the peatlands ability to respond to external pressures such as climate change. Furthermore, beaver dams increased surface and groundwater storage, which has implications for regional water balances, especially in times of drought.

Flood risk management in the Canadian prairie provinces: Defaulting towards flood resistance and recovery versus resilience

Major flood events are likely to happen more frequently and be more severe under changing land use and climatic conditions. Adapting to floods using resilience-based flood risk management (FRM) policies and initiatives is a more appropriate solution than relying solely on flood defence structures or disaster recovery programmes. The primary authority for FRM in Canada is the provinces, but in practice, the policies and responsibilities are distributed across complex, multi-departmental, multi-scalar systems of government. To examine the extent to which institutional arrangements for FRM facilitate or constrain FRM resilience, this paper uses a case study of FRM policies, instruments and practices in the three Canadian prairie provinces where floods have been particularly severe in recent years. Document analysis provided insights into current FRM policies and instruments while semi-structured interviews with 34 individuals working in an FRM capacity informed the roles and responsibilities for FRM implementation. Results indicate that the current FRM policies and instruments across the prairie region have the basic requirements for flood resilience. However, flood resilience is inherently challenged by institutional fragmentation, lack of clarity of FRM roles and responsibilities, and policy layering and competing mandates, which biases FRM towards resistance and recovery solutions. To go beyond solely coordinating flood emergency response and recovery, the paper suggests an overarching regional or national FRM strategy and boundary organisation to coordinate roles and responsibilities for the specific purpose of flood resilience. This requires an agency with the mandate to manage FRM policy instruments, and clearly allocate decision authority amongst the multiple levels and layers of FRM governance.