Research Projects

Current Research Projects

Current research is focused on the role that diversity plays in providing ecological functions, understanding the dynamics and structure of channel catfish in Nebraska reservoirs, invasive species risk assessments and distribution modeling, the Nebraska Landowner Incentives Program, the occurrence of amphibians in Nebraska Rainwater Basin wetlands, documenting predator fish control on white perch populations, understanding how resilience is generated in ecological systems, assessing the value of grassland habitats songbird production in three national parks, understanding river otter home range and habitat, and the recruitment of walleye and white bass in irrigation reservoirs .

Scroll down through the page or click on one of the following links:

1. Amphibians Monitoring Techniques–Rainwater Basin Region
2. Assessing local and regional variability in productivity and fidelity of grassland birds on National Park Service units in the Great Plains
3. Cross-Scale Structure in Ecosystems
4. Diversity and Ecological Functions
5. Evaluation of Landowner Incentives Program (LIP)
6. Impact of White Perch on Walleye
7. Monitoring, Mapping and Risk Assessment for Non-Indigenous Invasive Species in Nebraska
8. Population Assessment of Channel Catfish in Nebraska
9. Predators of White Perch at Branched Oak and Pawnee Reservoirs
10. Southeast Prairies BUL and Sandstone Prairies BUL Research
11. Recruitment of Walleye and White Bass in Irrigation Reservoirs
12. Resilience in Ecosystems
13. River Otter Home Range and Habitats Use Pilot Study
14. Spatial Risk Assessment of Invasive Species Impacts on Native Species in Nebraska
15. Understanding Invasions and Extinctions

We developed a pilot program focused on the spatial distribution of wetlands in Nebraska’s Rainwater Basin landscape.  Results will help guide management activities in this ecologically important region and serve as a model for similar monitoring and study in other herpetologically rich areas.

GOALS: Our goal is to establish a program to monitor populations of amphibians in south central Nebraska's wetland complex in order to detect changes in presence in this region over time (if monitoring is continued). The acquired data will provide inferential insight into the presence or absence of amphibian species and changes in individual species presence and community composition. We expect that if our methodologies are proven usable by Nebraska Game and Parks Commission staff as a way to assess land management practices, they will readily translate to other regions where similar land management is being implemented.

CURRENT STATUS: We gathered data that can provide inferential insight into the presence, or absence, of amphibian species and changes in individual species presence and community composition 1) following ongoing restoration activities, 2) following ongoing anthropogenic landuse/landcover changes, 3) in relation to existing wetland-patch network characteristics, 4) in relation to adjacent upland landuse/landcover and, 5) in relation to environmental contaminants originating as runoff from adjacent farmed lands. Additionally, we assessed biases associated with amphibian call surveys and utilized methods to account for differences in detectability inherent in call survey techniques. Data collected will be provided to the national monitoring program as well. A manuscript was published in the February 2007 issue of the Journal of Wildlife Manage­ment, “Observer Bias in Anuran Call Surveys.” GIS spatial analysis continues

GRADUATE RESEARCH ASSISTANT: Aaron Lotz

FUNDING: The Nebraska Game and Parks Commission

PROJECT PI: Craig R. Allen, NE CFWRU

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Assessing local and regional variability in productivity and fidelity of grassland birds on National Park Service units in the Great Plains

Little is known about the relative value of grassland habitats in National Park Service (NPS) units to regional songbird production. This study will provide NPS managers with an assessment of habitat quality for breeding grassland birds at three study areas, and assess the success of the unique methods (stable isotope techniques) used in the study.

GOALS: Avian nest survival will be intensively monitored in three NPS units (Pipestone National Monument, MN; Homestead National Monument, NE; and Tallgrass Prairie National Preserve, KS). Stable isotope values will be determined for feather and blood samples taken from nestlings and breeding adults. The two target grassland bird species are meadowlarks (eastern and western), and dickcissels.

CURRENT STATUS: Researchers visited the three sites in preparation for field research. Graduate student, Sarah Rehme, joined the project in January 2008. Technicians were hired and trained and field research began in May 2008.

GRADUATE RESEARCH ASSISTANT: Sarah Rehme
TECHNICIANS: Jenna Frank, Nathanei Haase, Mary Lugg, Ashton Mueller, Ryan Rezac, Sally Tucker

FUNDING: USGS Natural Resource Preservation Program (NRPP) and the National Park Service

PROJECT PI: Craig R. Allen, NE CFWRU; Larking Powell, University of Nebraska–Lincoln

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This research was motivated by the discovery of regular patterns of deviation from scaling laws and the continuous distributions of attributes of complex systems. These suggest that systems organize over discrete ranges of scale, and that organization abruptly shifts with changes in scale. If this is so, scaling laws serve only as the baseline from which to measure those departures, and those departures indicate “scale breaks” (transitions) between scales of structure in complex systems. Patterns of scale breaks from a scaling law baseline may provide clues of the processes that lead to the emergence of the scaling relationships themselves. At the minimum, investigating departures from scaling laws give us a clue into the nature of structure and process of the system in question and helps us understand and perhaps predict phenomena that have puzzled ecologists and other scientists, such as the generation of biological diversity and the emergence of resilience.

Complex behaviors such as migration and rapid adaptation leading to speciation may evolve most efficiently and commonly at scale breaks, where there is the greatest potential reward, although with the highest potential cost. This project specifically investigates cross-scale structure and its implications in ecosystems.

GOALS: We are conducting a series of empirical analyses to determine the distribution of functional groups within and across scales, the association of measures of biotic variability in vertebrates (e.g., invasions, extinctions, nomadism, migration) with discontinuities in body mass distributions, and cross-scale analyses of patterns in body mass distributions from local to hemispheric scales. Data sets examined so far include four different taxa in two different ecosystems.

CURRENT STATUS: Analysis of Mediterranean-climate data is complete and a report is in final revision.

GRADUATE RESEARCH ASSISTANT: Aaron Lotz and Don Wardwell (MS 2006)

FUNDING: The James S. McDonnell Foundation–Studying Complex Systems

PROJECT PI: Craig R. Allen, NE CFWRU

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GOALS: This project seeks to understand how the diversity of grasslands affects ecological services. The current focus is on herbivory.  

CURRENT STATUS: The pilot year of data collection (2005) focused on pollination and herbivory. Preliminary analysis indicates that pollinator diversity and visitation rates are greater over time on grassland sites having higher diversity, and that herbivory rates are lower on more diverse sites.

Field research in 2006 and 2007 focused on herbivory and invasion resistance. We identified high diversity restorations and low diversity remnant grasslands (pastures) as study sites.  Twenty-four 0.75-acre plots were established which are planted to six replicates each of four treatments: high diversity sites of ~100 species, high diversity sites at twice the normal seeding rates (to be similar with NRCS practices), and CP25 sites (15 species) at normal and half-normal seeding rates. These sites are being used to assess invasion resistance among the treatments, and to assess soil development and nematode populations. Large scale sites are being used to investigate differences in herbivory. We will also investigate the export of herbivory reduction to adjacent row crop agricultural fields.

Kristine Nemec focused on populations of economically-significant grasshoppers and the pest control provided by predatory invertebrates. She collected data for soil development and invasion resistance. Insect samples continue to be sorted and analyzed. Arachnid expert Hank Guarisco of Kansas is identifying the spider specimens to species. Data collections are nearly complete with data analyses to follow. Lindsey Reinarz finished three samples of herbivory rate and insect sweeps. She conducted vegetation sampling of her fields and an additional herbivory sampling and observation of which insects actually visit the plants. Insect analysis and identification are nearly complete; analysis of the floral quality at the research sites is next. Information and data will be collected to help explain emerging relationships.

GRADUATE RESEARCH ASSISTANT : Kristine Nemec, Ph.D. (also U.S. Army Corps of Engineers); Lindsey Reinarz (University of Nebraska at Omaha)
TECHNICIANS: Michelle Hellman, Katy Dornbos, Brian Franzone

FUNDING:  The James S. McDonnell Foundation–Studying Complex Systems, the Nebraska Game and Parks Commission. Additional collaborators include the Nature Conservancy, the University of Nebraska Omaha and the Natural Resources Conservation Service.

PROJECT PI: Craig R. Allen, NE CFWRU

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The size of the Landowner Incentive Programs and Partnerships in terms of funding, cooperation and stakeholder involvement requires an assessment of program success. Such an assessment should be an adaptive process that will continue throughout the implementation of the program.  During this early stage of the Landowner Incentives Program, the assessment needs to proceed on two fronts: landowner involvement and the response of species at risk.

GOALS:  This research project focuses on the response of species at risk. Assessment has focused on elements that are likely to respond rapidly, such as vegetation structure (which are directly manipulated in the LIP), insect communities (which have short generation times), and bird communities (which respond to vegetative structure).   

CURRENT STATUS: In 2005, pretreatment, base-line data were collected and followed by the removal of invasive trees such as red cedar. This data included assessment of vegetation using the Floristic Quality Index, and estimation of bird densities. Herpetofauna data was collected using coverboards, but was sparse and discontinued for 2006. The second, 2006, season of data collection focused on bird species using transect methods, and is currently being analyzed. 

This project is complete with results compiled into a master’s thesis. Changes in bird species and populations resulting from tree removal did not reflect a basic shift from woodland to grassland species. In some cases, large piles of unburned trees continue to provide cover or nesting habitat for woodland species within a grassland environment.

GRADUATE RESEARCH ASSISTANT: Beth Forbus (MS 2007)
TECHNICIANS: Meghan Halabisky, Ryan Rezac, Chad Brock, Lizette Peters

FUNDING: The U.S. Geological Survey, and the Nebraska Game and Parks Commission Landowner Incentives Program (LIP)

PROJECT PI: Craig R. Allen, NE CFWRU

Impact of White Perch on Walleye and

Predators of White Perch at Branched Oak and Pawnee Reservoirs

Habitat alterations and accidental introduction of white perch into Branched Oak Lake have shifted the fish community from one dominated by littoral (near-shore) species (e.g., largemouth bass and bluegill) to one dominated by pelagic (open-water) species (e.g., white perch and gizzard shad). Along with the change in the fish community, angler trips to Branched Oak Reservoir have declined by 85% over the last two decades. Further, the white perch population has become stunted (high density of slow growing individuals that mature at a small size). Like Branched Oak Lake, Pawnee Lakehistoricallysupported an active and diverse fishery, and has experienced similar habitat alterations and accidental introduction of white perch. However, unlike Branched Oak Lake, stunting has not yet occurred for the white perch population in Pawnee Lake.

These two companion projects are an opportunity to examine whiteperch interactions with other fishes in two similar Nebraska reservoirs having different white perch population stages (i.e., stunted and non-stunted). Food habits and diet overlap among white perch, crappie, walleye, white bass, and channel catfish are being evaluated.

GOALS: This project will help document potential competition bottlenecks that exist between white perch and other fish species of importance in the hopes ofdeveloping a management program to eliminate stunted status for the white perch population in Branched Oak Lake and to prevent stunting of the whiteperch population in Pawnee Lake.

CURRENT STATUS: Fish stomachs are pumped and the contents are analyzed to understand which fish species prey on white perch. All stomach content samples have been analyzed and data synthesized. Stable isotope analyses of stomach contents were conducted and confirmed results. A master’s thesis is being written.

FUNDING: U.S. Geological Survey, and the Nebraska Game and Parks Commission

GRADUATE RESEARCH ASSISTANT: Nathan Gosch
UNDERGRADUATE ASSISTANTS: Landon Pierce, Jeff Stittle and John Walrath

PROJECT PI: Kevin Pope, NE CFWRU

Click here to read the Lincoln Journal Star article about the white perch study.

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Biological invasions are a growing threat to both human enterprise and ecological systems. This project provides resources to the public and private sector on 1) the potential spread and impact of non-indigenous species in Nebraska, 2) actual and potential maps of non-indigenous species range (habitat specific maps at high resolution), 3) information regarding identification and management of potential invaders, 4) centralized information on management and impacts and potential spread of currently established non-indigenous species (a Web portal), 5) outreach within Nebraska to county-level governments and individual stakeholders regarding the management, surveillance and control of non-indigenous species, and 6) an organizational and informational Nebraska conference on non-indigenous species impacts—their spread and management—focusing on state-of-our-knowledge, and coordination of disparate management and information-provisioning efforts with a goal towards unifying disparate efforts.

GOALS: This new research project will help build a cohesive non-indigenous species biosecurity and management system in Nebraska that is integrated and relatively seamless across institutional boundaries. This project will also map the potential spread of many invasive species in Nebraska.

CURRENT STATUS:  A Web site has been developed which serves as a centralized clearinghouse on identification, management, impact and potential spread of currently and potentially established non-indigenous species. A Nebraska invasive species conference was hosted in Lincoln, Nebraska on February 7 - 8, 2008. It was attended by about 150 people from across Nebraska who represented a broad array of agencies and organizations. Additional conference information can be found at the project's Web site.

The following article, authoried by Annabel Major and Craig Allen, appears in the April 2008 edition of Prairie Fire. It describes the threat of invasive species and what it means to Nebraskans, Invasive species in Nebraska: The battle for Nebraska's natural legacy. The article can be found at: http://prairiefirenewspaper.com/ Do a Search for "invasive species" to bring up the article title.

WEB SITE: http://snr.unl.edu/invasives

GRADUATE RESEARCH ASSISTANT: Justin Williams
PROGRAM COORDINATOR: Annabel Major

FUNDING: Nebraska Environmental Trust

PROJECT PI: Craig R. Allen, NE CFWRU

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Population Assessment of Channel Catfish in Nebraska

To aid in the management of channel catfish populations in Nebraska—a fish highly desired by anglers—the Nebraska Game and Parks Commssion (NGPC) currently samples catfish in reservoirs using gill nets set during autumn. The NGPC fisheries management would like to shift to a new methodology for standard catfish sampling that has been used by a number of midwest states: tandem, baited hoop-net series for lentic catfish sampling. This project will provide baseline information on channel catfish populations in Nebraska's lentic systems as measured using tandem-bated hoop nets, describe differences in population charateristics among water-body types, and stocking protocols. Further, we will compare indices of population characteristics derivwed from two different sampling methods—the gill net method, and the tandem-bated hoop nets method.

GOALS: The purpose of the project is to gain an understanding of the present variability in the dynamics (recruitment, growth and mortality) and structure (abundance, size- and age-structure, and condition) of channel catfish populations found in reservoirs throughout Nebraska. This information will help managers determine the need for future stockings and harvest regulations of channel catfish.

CURRENT STATUS: The project was just recently funded with a start date of January 2008. Lindsey Richters will provide graduate student research support. Research equipment has been procured and technicians hired for the first field season which began in May 2008.

GRADUATE RESEARCH ASSISTANT: Lindsey Richters
TECHNICIANS: Chad Dobesh and Nick Dobesh

FUNDING: Nebraska Game and Parks Commission

PROJECT PI: Kevin Pope, NE CFWRU

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Southeast Prairies BUL and Sandstone Prairies BUL Research

In 2007 the Southeast Prairies Biological Unique Landscape (BUL) and Sandstone Prairies BUL were included in a Flagship Initiative approved by the Nebraska Natural Legacy Project’s Partnership Team. In the flagship proposal, The Nature Conservancy (TNC) was designated as the lead agency to conduct the research and monitoring portion of the project. The Northern Prairies Land Trust (NPLT), Nebraska Game and Parks Commission (NGPC), Nebraska Cooperative Fish & Wildlife Research Unit at the University of Nebraska–Lincoln, and the University of Nebraska at Omaha were designated as partners in the research and monitoring component of the project. Those partners and others will work together to design and implement a range of research and evaluation projects, which will help drive conservation work within the Southeast Prairies and Sandstone Prairies BULs. The fragmented nature of the landscape within the BULs creates challenges for conservation. Little is known about how habitat patch size and connectivity between patches influences at-risk species and natural communities.

GOALS: The goal of the initial data collection is to sample native prairies of various size, quality, and isolation to determine these factors impact on tallgrass prairie biodiversity. The initial portion of the study for which data is being collected in 2008 is to determine if these factors affect insect populations. Results from this summer’s work will guide development of future research efforts. Understanding more about these issues will help make informed decisions regarding project size, priority landscapes, and project design in eastern Nebraska landscapes.

CURRENT STATUS: Preliminary data collections were started in summer 2008. FQA data were collected on 16 research sites. Following this, insect seep netting took place on the same sites. Data analysis will continue through fall 2008.

GRADUATE RESEARCH ASSISTANTS: none
TECHNICIAN: Chris Wood
BOTANIST: Alicia Admiraal

FUNDING: The Nebraska Game and Parks Commission

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The five reservoirs within the Republican River watershed in southwest Nebraska (Swanson, Enders, Red Willow [also referred to as Hugh Butler], Medicine Creek [Harry D. Strunk], and Harlan County) were built primarily for flood control and irrigation, resulting in large water-level fluctuations within and between years. These reservoirs also provide important fisheries for anglers in southwest Nebraska; walleye and white bass are of particular importance in these reservoirs. However, continued annual stockings of walleye have been necessitated because of low natural reproduction and recruitment of young. In contrast, white bass populations are self-sustaining within these reservoirs, although recruitment is extremely erratic (i.e., weak or missing year-classes are common) in all but Harlan County Reservoir. We believe that a “recruitment bottleneck” could exist for walleye and perhaps white bass in these irrigation reservoirs. Click here for map and additional information on these four southwest Nebraska reservoirs.

GOALS: The purpose of this project is to gain an understanding of the factors affecting recruitment of walleye and white bass in Enders, Medicine Creek, Red Willow, and Swanson Reservoirs. The primary focus will be documenting the relative importance of spawning habitats and determining when the suspected recruitment bottleneck for walleye and white bass occurs in southwest Nebraska irrigation reservoirs. This information is vital for understanding reservoir fish ecology in semiarid regions. 

CURRENT STATUS:  In September and October 2006, 30 walleye and 30 white bass were implanted with transmitters. The fish were located in Swanson, Enders, Medicine Creek Reservoir, Red Willow Reservoirs. The 2006-07 season of field sampling included collections of larval and juvenile fishes. Acoustic telemetry, electrofishing, egg mats, and larval light traps were used to assess relative importance of spawning habitats. In fall 2008, an additional 30 walleye and 30 white bass were implanted with transmitters to facilitate tracking during spawning.

The second field season is underway. Adult walleye and white bass are being tracked with telemetry to identify spawning sites and assess associated habitats. 2008 is the second and final year for the telemetry portion of this study. Collections of larval fish began in April 2008. Creel surveys for 2008 began in April and will continue through October to gather data on species of fish being caught by anglers. Preliminary models describing walleye recruitment were developed; recruitment appears to be positively related to stocking events and negatively related to water withdrawals associated with irrigation

GRADUATE RESEARCH ASSISTANT: Christopher Lewis, Dustin Martin
UNDERGRADUATE ASSISTANTS: Ted Ehly, John Walrath
CREEL CLERKS: Greg Hoffman, Marlin D. Miller

FUNDING: Nebraska Game and Parks Commission

PROJECT PI: Kevin Pope, NE CFWRU

In 1998, the model of cross-scale resilience was proposed. One prediction following from that model is that birds of different body size respond differently to resources as they “scale up” and aggregate in larger concentrations. An example of this occurs with pest outbreaks—when larger volumes of trees are infested with insects such as spruce budworm, larger bird species begin to exploit the pest, and are drawn from broader areas to do so. This provides a robust check on outbreaks over a broad range of spatial and temporal scales.

GOALS: We are conducting experimental and empirical tests of the model of cross-scale resilience.

CURRENT STATUS:  We have conducted simulations comparing actual distributions of function across animal size classes against simulated distributions, and found that the richness of function across size classes in real ecological systems is more constant than expected. Field research began in May 2006 to measure the difference in spatial response of birds of different body size to resources aggregated at different levels in row crop agricultural fields. Analysis of that data is currently underway.

GRADUATE RESEARCH ASSISTANT:  Don Wardwell (graduated December 2007)

FUNDING: The James S. McDonnell Foundation–Studying Complex Systems

PROJECT PI: Craig R. Allen, NE CFWRU

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River Otter Home Range and Habitats Use Pilot Study

River otters have become reestablished in Nebraska after their reintroduction in the mid 1980s and early 1990s. The species is currently listed as threatened in Nebraska (S2). Despite the high profile of the reintroduction and the otters’ role as a flagship species, relatively little is known about river otter ecology in Nebraska. The Nebraska Cooperative Fish and Wildlife Research Unit with the Nebraska Game and Parks Commission initiated this project in October 2006 with the objective of collecting home range and habitat use information on river otters along the big bend area of the Platte River using remote sensing (radio telemetry).

GOALS: This project is collecting home range and habitat use information on river otters along the big bend area of the Platte River using radio telemetry. Data collected, in conjunction with the results of an ongoing river otter health and reproductive survey and results from NGPC’s annual otter bridge survey, will help to close existing information gaps and contribute to the creation of the Nebraska River Otter Management Plan and the Statewide Comprehensive Conservation Plan.

CURRENT STATUS:  River otters were implanted with transmitters: five in fall 2006 and an additional eight in fall/winter 2007. Tracking found two females that set up natal dens in spring 2007. One otter was found to have traveled about sixty miles downstream. Tracking of the thirteen implanted otters continues. The final trapping/implanting season will begin in September of 2008.

GRADUATE RESEARCH ASSISTANT:  Sam Wilson (also Nebraska Game and Parks Commission)
TECHNICIAN: Kent Fricke

FUNDING: Nebraska Game and Parks Commission

PROJECT PI: Craig R. Allen, NE CFWRU

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This project conducts spatially-based risk analyses for species and communities identified as at-risk. This project focuses on assessments of the risk to native species from non-native invasive species in Nebraska. It will also conduct community-level risk assessments to evaluate the risk faced by those communities identified as “at-risk” by the Nebraska Game and Parks Commission Legacy Project. Modeling of both stressors and targets will be based on species-habitat associations with the use of relevant auxiliary data, as per Gap Analysis protocols. Several different GIS landcovers are available for the State of Nebraska and we will likely have to make use of several of them, as all have different strengths and weaknesses. Where possible, we will utilize the methods described in Allen et al. (2001) to incorporate minimum viable population modeling based on minimum critical areas for vertebrate models. Products will include spatial models of stressors and targets, models of spatial overlap, hazard indices, and relative risk indices for each target. Stressors (invasive species on the Nebraska Watch List) and targets have been identified and modeling is currently underway.

GOALS: This project conducts spatially-based risk analyses for species and communities identified as at-risk by the Nebraska Legacy Project. Stressors are invasive species on the Nebraska noxious weed watch list. Results may provide guidance for invasive species surveillance and monitoring, and prioritize research and management needs regarding specifics of impacts.

CURRENT STATUS: Stressors (invasive species on the Nebraska Watch List) and targets have been identified and modeling is currently underway.

GRADUATE RESEARCH ASSISTANT: Thad Miller

FUNDING:  Nebraska Game and Parks Commission, and the U.S. Geological Survey

PROJECT PI: Craig R. Allen, NE CFWRU

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Mediterranean-climate regions support large human populations resulting in extensive, and outside the Mediterranean Basin proper, rapid, anthropogenic transformation. Compared to other continental areas, Mediterranean regions have been invaded by a large number of non-indigenous organisms, including vertebrates. Concomitant with invasions, declines and extinctions have transformed the faunas of Mediterranean ecoregions.

Goal: Project objectives are to 1) compare the vertebrate body mass structures of Mediterranean-climate ecosystems, and 2) examine the effects of invasions and extinctions in Mediterranean-climate ecosystems on body mass structure and alpha, beta and gamma diversity.

CURRENT STATUS: Analysis is complete and a report is in final revision.

GRADUATE RESEARCH ASSISTANT: Aaron Lotz

FUNDING: U.S. Geological Survey

PROJECT PI: Craig R. Allen, NE CFWRU  

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