Threats to Great Lakes ecosystems are expected to increase as human populations grow and demand on natural resources intensifies. To protect Great Lakes resources, the USGS-GLSC is anticipating emerging threats and developing approaches to study rapid ecological change. One of the most widely-recognized emerging issues is global climate change. The USGS-GLSC is completing research to understand the physical phenomenon of changing climate and document and predict the ecological responses to that change. Current USGS-GLSC research focuses on understanding how climate change affects animal communities and fish production, and long-term effects on aquatic processes, such as temperature stratification in Lake Superior. In addition, the potential effects of climate change (e.g., lower water levels in the Great Lakes) are integrated into research efforts to promote analysis that will remain relevant over time.
What are the climatic and species characteristics that make animal populations, species, and communities vulnerable to decline and redistribution as climate changes?
- Predict the response of the Karner blue butterfly to likely changes in climate and provide the National Park Service with possible management responses to mitigate negative effects of climate change on this endangered species.
- Predict continental scale responses of breeding bird community characteristics to 21st century projected climate change.
- Describe differences in native bee communities between geographically limited climate-sensitive habitats and less vulnerable habitats across a range of national parks. Climate vulnerable habitats are landscapes in which escape from negative effects of climate may be most limited -- for example, high elevation habitats in which species movements upslope to escape rising temperatures are terminated at mountain tops.
Background & Justification
Justification for selected objectives: Our understanding of the response of animal communities to climate and climate change is influenced by scale and methodology -- geographic scale of modeling, statistical modeling versus process based modeling that predicts species' distributions based on species' biophysical tolerances. Animals' response to climate change is influenced by life history and dispersal ability -- susceptibility of different life stages, ability to move across the landscape. The objectives below examine animal response to climate change along these dimensions -- statistical models that examine the effects of climate on bird distribution and process based models that rely on detailed information gathered at a local level for the Karner blue butterfly and that show how subtle the effects of climate on the entire species life cycle can be. While the statistical model approach allows us to examine broad scale changes that are important to guide and inspire conservation and political action, the process based approach drills down to mechanisms of local adaptation and may well be more reliable and, perhaps, even more globally informative despite the more limited geographic domain examined. The search for generality and principles guides the projects selected. The topics studied, the Karner blue, birds, bees, are important in their own right according to our DOI mission -- assisting recovery of endangered and trust species, assigning a leading role to USGS in the assessment and management of pollinator populations -- but the combination of approaches increases the ability to contrast results and understand strengths of each approach.
A. Karner blue butterfly
One of the few remaining populations of the federally endangered Karner blue butterfly (Lycaeides melissa samuelis) resides at Indiana Dunes National Lakeshore (INDU). Overall, Karner blue population counts at INDU have declined since the late 1990s despite ongoing habitat management. Recent studies (Fuller 2008) suggest that microclimate and climate change might play a role in this decline. Understanding possible effects of climate change has been identified as a priority need in the recovery of the Karner blue (U.S. Fish and Wildlife Service 2003) because climate change might create conditions to which the species is poorly adapted, either physiologically or ecologically. Therefore, modeling how climate change might affect the future of the Karner blue at Indiana Dunes (INDU), and translating those predictions into management recommendations for increasing ecosystem resiliency in the face of changing climate, is important if the National Park Service is to improve the chances of adequately managing the landscape for this species at INDU over the next several decades.
B. Continental Response of Bird Communities to Climate Change
Characteristics of animal or plant communities, such as diversity, can serve as a metric for setting management and conservation goals for landscapes the communities inhabit. However, choosing a specific metric as the measure of management or conservation success can be difficult because multiple characteristics of the managed community may be suitable goals. If it is possible to enhance several desirable characteristics concurrently at a given location, management goal-setting or site prioritization for conservation, conceptually, is easier. However, management actions that improve the condition of one desirable community characteristic can degrade another desirable characteristic. Typically, we do not know how these characteristics co-vary and, hence, we do not understand what tradeoffs might arise from management or ecosystem perturbation emerging from human activities. Our lack of understanding of co-variation of multiple conservation relevant attributes is true even for well-studied taxa, such as land birds in the U.S. for which detailed, large scale conservation plans exist. Although conservation-planning goals are often expressed in terms of biodiversity, other goals may be set. Maintenance of historic habitat structure or historic ecological processes, conservation of endemic species, and helping threatened species are examples of alternative conservation goals. In this project, I examine several characteristics associated with U.S. bird communities that might form the basis of a conservation goal metric, including bird abundance, community richness, retention of the most threatened bird species in a community, frequency of landscape use by birds, and maintenance of the ecological gradient along which birds in the U.S. are distributed and examine how changing climate might affect both distribution and co-variation of these characteristics.
C. Response of native bee populations to climate change
Worldwide, native bees provide hundreds of billions of dollars of ecological services annually through pollination of plants. Approximately 4000 native bee species are known in the U.S. and are critical for pollinating many native plant species and agricultural crops. Significant declines of managed honeybee populations and frequent extirpations of native bumblebee populations in the U.S. indicate that some species, and their associated functions, are in jeopardy of decline or loss. These declines are likely related to global change including climate change. The nature of native bee distribution and loss is not well documented due to lack of systematic evaluation of native bee communities. In a USGS sponsored report, the National Research Council (2007) recommended the USGS take the national lead in organizing such large scale evaluations of pollinator distribution and trends. In this job, native bees are being inventoried in more than 60 national parks spanning the continental U.S. in coastal, high elevation, high latitude, and arid landscapes that have been identified as of special concern due to limits on retention of species in these habitats with changing climate. This project compares bee communities in these landscapes of special concern to paired landscapes of opposite quality to understand habitat specificity of native bees and to evaluate climate sensitivity of these native bee species.
Great Lakes fishery managers have little information regarding how proposed climate change arising from rising greenhouse gas emissions will affect the management and conservation of fish populations (including those of high recreational and commercial value). To that end, our work aims to provide knowledge to aid managers in their planning and anticipation of coming changes. First, we will update a regional climate model to provide more accurate estimate of predicted water level changes, as well as depth-specific water temperature and % ice cover data for 50-75 years into the future. Second, we will use satellite data to explore the linkage between annual primary productivity and winter and spring warming rates. Third, we will use time series models to explore how these important climate-related variables (in addition to other important biotic factors) explain variability in fish recruitment using long-term data sets. Fourth, we will use parameters derived from these analyses and predicted climate variables to forecast fish recruitment over the next 50-75 years. Finally, we will use bioenergetics modeling to explore how warmer water temperatures will influence the growth and consumption rates of several managed fish species.