Accelerating changes and transformations in western mountain lakes

Science Center Objects

While research into eutrophication has been a cornerstone of limnology for more than 100 years, only recently has it become a topic for the remote alpine lakes that are icons of protected national parks and wilderness areas. National park lakes in the western U.S. are threatened by global change, specifically air pollution, warming, and their interactions, and the problem is quickly worsening. Algal blooms may indicate a major state change and have ramifications for lake food webs and human health. Using monitoring, surveys, paleolimnology, remote sensing and experiments, we are studying this unwelcome progression toward eutrophication while testing management opportunities that may slow or reverse greening.

Statement of Problem:

Western mountains are increasingly subject to accelerating and transformative changes in lake and watershed processes driven by alterations in water and ecosystem dynamics from warming and nutrient inputs. Warming temperatures West-wide are driving earlier snowmelt, glacier retreat, and trends in lake warming. Nutrient inputs from wet and dry deposition, including dust, and increasing recreational use contribute to trends in eutrophication of iconic mountain lakes that are important biodiversity reservoirs and tourist destinations. Park visitors who return to favorite lakes year after year report changes such as pond scum where it wasn’t before. Our research addresses the causes, consequences, and possible remedies for mountain lakes throughout the western United States, including those in national parks and wilderness regions.

                                                                 

Why this Research is Important

This 2019-2023 project addresses emergent changes in lake and watershed patterns and processes in response to climate variability and nutrient inputs in western landscapes. This project continues development of intensive, place-based, long-term ecological datasets, which are scaled-up through participation in more extensive networks to conduct regional and West-wide analyses and syntheses.  We are a part of the Western Mountain Initiative, which explores the effects of climate drivers on forest vegetation, ecological disturbance processes, mountain hydrology, and the coupled ecohydrological responses that determine vulnerability of western US mountain landscapes to change (see Figure below).

WMI Diagram

Figure credit: J. Baron

The importance of our research is underscored by several federal priorities and directives including the FY19 Presidential priorities to 1) utilize remote sensing to develop efficient methods for evaluating lake algal biomass across all western mountain lakes and 2) provide assessments and deliver the research, tools, and data that will enable managers of the National Park Service and other public lands to understand, track, and monitor changes in the condition of mountain lake ecosystems at scales relevant to decision-making. Further, our research directly aligns with the Department of Interior Mission Area of “Conserving our Land and Water” and facilitates the successful realization of several subordinate goals such as conducting science to inform land, water and species management for national parks. By increasing understanding of how and when interacting drivers of change influence lake trophic state, we help inform resource managers of western mountain national parks of the potential for harmful algal blooms, some of which have already been documented in western lakes.

 

Objective(s)

The objectives of our research are to understand and identify the multiple causes of changes in mountain lakes throughout the western United States, quantify the rate and extent of these changes, and explore possible remedies for these changes with an emphasis on lakes in national parks and wildernesses. Our goals are to inform resource managers about the history, current state, and rates of changes in mountain lake trophic state (oligotrophic, mesotrophic, eutrophic), frame results in terms of threats to park resources and human health, and to identify management actions that might help avoid undesirable outcomes.

To achieve these goals, we conduct research and monitoring founded on the following:

1. Continue long-term monitoring and research in Loch Vale watershed, Rocky Mountain National Park, to identify high resolution temporal patterns, causality, and ecological response. The 36-year continuous record is highly valued by the National Park Service and other federal agencies with similar natural resources under their protection (FY19-FY23).

2. Coordinate a community of mountain lakes scientists, including those from nine national parks and the Pecos Wilderness, to develop models based on first principles, experiments, and observations that explain current lake conditions and potential future trajectories (FY19-FY23).

3. Develop a proof of concept that remote sensing can be used to assess the extent of lake greening across high elevation western mountain lakes.

4. Assess the efficacy of top-down ecological management of alpine lake food webs as an effective adaptive management approach. We will work with Rocky Mountain and Sequoia National Parks to select certain lakes for fish removal to test whether there is potential to achieve multiple goals, from restoration of native food webs to eutrophication abatement (FY21-FY23).

 

Methods:

To achieve our objectives, we integrate a host of methods including continued long-term monitoring in Loch Vale watershed, Rocky Mountain National Park that measures precipitation and water chemistry, meteorology, hydrology and limnology. Additionally, remote sensing, experiments, and paleolimnological reconstructions of algal assemblages through stable isotopes, pigment and eDNA analyses are used.