Jake Vander Zanden, Ph.D. - US grants

Freshwater lakes around the world provide essential ecological and human benefits that range from aquatic habitat to sport and commercial fisheries to safe and reliable drinking water. The goal of the North Temperate Lakes (NTL) Long-Term Ecological Research Program is to understand how and why lakes change over time and to determine the consequences of these changes for these and other basic services. The research focuses on two sets of lakes and their surrounding landscapes. One set lies in the rural, forested, and tourist-dominated Northern Highland Lake District in northern Wisconsin and the other lies in the agricultural and urban landscape around Madison, Wisconsin's capitol. Studies of these contrasting settings provide insights into how individual lakes and groups of lakes across landscapes and regions are affected by phenomena such as shifting climate conditions, large storm events, invasive species, harmful algal blooms, urbanization, and changes in environmental policies. The project implements a number of different approaches to collect data over long time periods and to analyze these long-term observations. Results improve understanding of ecological change in lake districts that is important to anyone concerned with the future of a particular region, its freshwater resources, and the welfare of its residents. Results are also integrated into multiple educational and training activities. The NTL program is committed to supporting diversity in science, and to outreach efforts that communicate scientific findings and expertise to broad audiences, informing individuals, non-governmental organizations, academics, and local, state and federal agencies.

The project will address the overarching question of how biophysical setting, climate, and land use and cover interact to shape lake dynamics and organization in the past, present and future. Activities will be organized in thematic areas that involve (1) documenting, describing, and interpreting long term change in lakes and lake districts; (2) exploring how past and potential future climate conditions influence lake physical, chemical, and biological processes; (3) understanding how and why long-term changes vary spatially within and among lakes; and (4) examining how lakes and lake districts respond to sudden changes, extreme events, or interacting drivers. The work informs and is informed by concepts and models from landscape ecology, disturbance ecology, and multiple causation. Questions will be addressed across a range of scales and topics, including within-lake changes in thermal regime and fish habitat in response to climate, abundance-impact relationships for aquatic invasive species among lakes; watershed organic carbon and phosphorus dynamics, regional water clarity trends, and many others. Research approaches include generating and analyzing long-term observations, experiments, comparative studies of multiple lakes, and diverse modeling and statistical tools. The research group comprises an interdisciplinary team with expertise in biogeochemistry, climatology, paleolimnology, demography, ecology (landscape, ecosystem, community, population, and paleo- ecology), economics, education and outreach, hydrodynamics, hydrology, information management, and microbiology. The multi-scale, multi-faceted NTL research program is designed to detect patterns of long-term change, evaluate and advance concepts to understand causes and consequences of these changes, and build forward-looking models and hypotheses that will be tested using future long-term observations.

Collaborative Research: Putting the Lake Back Together: Integrating littoral productivity into lake food webs
Jake Vander Zanden
University of Wisconsin-Madison

Lake shore (littoral zone) habitats of lakes are highly sensitive to human disturbances and activities. Lake biologists have traditionally directed their studies towards open-water (pelagic) components of lake ecosystems. As a result, the contribution of littoral habitats to lake ecosystems remains poorly known. What is their role in supporting lake biodiversity? What is their role in supporting fish populations? This project will assess littoral zone productivity relative to pelagic zone productivity, and will assess how the relative importance of these two habitats change with lake size and nutrient levels. Second, it will test the hypothesis that littoral zone productivity is more efficiently channeled up the food chain to support fish production, thus indicating a higher importance to littoral habitats for supporting fisheries. Third, it will test whether littoral habitats support more biodiversity than pelagic habitats. This research will also investigate connections between food chains in littoral and pelagic zones, and in doing so, will provide a more holistic understanding of how natural lakes function. Importantly, this work will provide mangaement insights into how littoral habitat destruction and lake eutrophication (nutrient enrichment) affect littoral zone productivity. This research will improve our understanding of these habitat changes and the implications for the productivity of higher trophic levels. Graduate and undergraduate students will be trained in limnology and analytical chemistry.

This award provides partial support for construction of a new, 1400 sq.ft., 4-bedroom housing unit that will increase housing capacity of the University of Wisconsin's Trout Lake Station by 20% and, in addition, provide needed small-group meeting space. The institution is providing additional funding to support the project. Trout Lake Station is located in the Northern Highland Lake District of Wisconsin, where it provides access to a wide variety of aquatic ecosystems and their surrounding landscapes. More than 2500 lakes are within 50km of the station. The station has a long history of aquatic research that continues to the present day. Recent research activity is reflected in 182 peer-reviewed publications and 28 graduate student theses attributed to projects conducted at the station since 2000. These are in addition to more than 800 publications and theses published prior to 2000. In addition to fostering research, the Trout Lake Station is used regularly for field trips by undergraduate and graduate courses from universities throughout the Midwest. Use of the station has grown to a level where housing capacity severely restricts both current activities and development of new research, teaching, and outreach programs. Use of the station has averaged about 9100 user-days/year over the last three years, a record high. The limited overnight housing at the station has begun to prevent the station prevent the station from welcoming visiting scholars, and impeded the ability of supervising faculty members to oversee the work of graduate and undergraduate students spending the summer at the station. Besides hosting research leading to new knowledge of the long-term dynamics of lakes, the impact of exotic species, and the impact of human activities, the station provides opportunities for student training, and outreach to the general public, including community participation in developing scenarios for the future of the Northern Highland Lake District, and presentations to community groups by local and visiting experts.

Food webs can be supported both by organic matter produced within an ecosystem and by organic matter produced elsewhere. In many lakes, for instance, inputs of terrestrial detritus substantially contribute to available organic matter. Recent research has quantified the extent to which these terrestrial subsidies are incorporated into the food web. However, these studies have been limited to very few lakes, making it difficult to understand the magnitude or drivers or variation in the importance of subsidies. This study seeks to overcome these limitations by testing an emerging new approach for quantifying terrestrial subsidies to aquatic consumers, and applying this approach across a suite of lakes. The investigators will combine laboratory experiments, field experiments, and comparative field surveys in order to refine the hydrogen stable isotope approach and provide new insights into cross-ecosystem subsidies.

As ecosystem management embraces landscape scales, measurements of cross-ecosystem flows assume greater importance in environmental assessments. This project will provide new measurements of cross-ecosystem flows while developing a powerful new method for measuring terrestrial-aquatic subsidies.

Non-Technical Abstract: C.Gratton
Proposal Number: DEB-0717148
Proposal Title: Linking Lakes to Land: Understanding the Spatial and Temporal Aspects of Allochthonous Subsidies


Our understanding of how lakes and land are linked is poor, despite the fact that lakes are important components of many terrestrial landscapes. Most research to this point has focused on how watershed characteristics or land use affect downstream surface waters, but we know little about reverse interactions. This study will investigate lake-to-land linkages at Lake Mývatn, a nutrient-rich lake in Northern Iceland with exceptional, natural, large-scale midge (aquatic insect) outbreaks that occur every 5-7 yr. During these outbreaks, millions of midges enter surrounding terrestrial ecosystems, where they affect everything from plant productivity to herbivorous insects and their spider predators. Through a series of manipulative experiments, remote sensing analyses, and empirical modeling, this system will serve as a model to study ecological linkages at the landscape scale and will address the fundamental question of how food webs on land are influenced by energy, materials, and organisms originating from separate and distinct lake ecosystems. Broadening our studies of terrestrial communities to explicitly include interactions with other elements of the landscape will allow us to better understand and manage our environment by considering multiple habitats simultaneously. Landscapes are being altered via both natural (e.g., invasive species) and anthropogenic forces (e.g., urbanization or agriculture). Determining how these dynamic patchworks of habitats affect each other will be essential to understanding how disturbances propagate through landscapes and to better managing our terrestrial ecosystems.

The effect of public policy on ecosystem services is complex, not only for the obvious reason that ecosystems are complex, but also because a policy's effect is filtered by the private decisions of individuals and households, often with unintended ecological consequences. An important example is public policy to control aquatic species invasions, which are often a major threat to native species and biodiversity, and consequently to the social value of aquatic ecosystems. This project investigates how policy interventions intended to control or prevent harmful aquatic species invasions affect the decisions and economic welfare of individuals using the aquatic system, and consequently the spatial dynamics of invasions. This question will be addressed for aquatic invasive species (AIS) now present in the lake district of northern Wisconsin, such as Eurasian water-milfoil, rusty crayfish, and zebra mussel. The analysis uses a variety of new data and methods, including an econometric model of boater behavior estimated with data from a two-year, web-based survey of boaters, novel experiments and analyses concerning propagule uptake by boats leaving infected lakes and propagule survival during transport, and a statistical model of the lake characteristics affecting propagule establishment and colonization.

As well as advancing understanding of aquatic species invasions, results will generally inform human-environment studies through the development of innovative models that incorporate uncertainties in human behaviors. On a practical level, the project will have broad impacts via its insights into basic management questions about AIS. For example, historically, management resources have been directed primarily towards invasive species control, possibly because of the political economy of invasions. But in reality, the appropriate management action is likely to be a mix of control and prevention; and methods falling into each of these categories need further investigation. Multiple graduate students and undergraduates will be trained and mentored in this interdisciplinary research project. Project personnel will work in Wisconsin with the North Temperate Lakes Long-Term Ecological Research site's Schoolyard program to educate K-12 teachers and students about the ecology and economics of such invasions.

The University of Wisconsin Trout Lake Station is awarded a grant to add a new conference room facility onto the existing main laboratory building. The 1500 square-foot wing will contain a 1050 sq. ft. multipurpose assembly room, restroom facilities, a kitchenette, and a multiple use basement. The assembly room will have a rated capacity of 70 people (chairs and tables) or 150 people (chairs only). This addition will allow the Trout Lake Station to host meetings, workshops, outreach events, and classes. Researchers at Trout Lake have been leaders in various regional, national, and international research groups including GLEON, NEON, and LTER. The new facility at Trout Lake will benefit these programs by providing adequate on site meeting space. The new addition will similarly enhance the Station's ability to conduct outreach activities for K-12 and the general public.

The Trout Lake Station benefits science and society by 1) creating new knowledge, including policy-relevant research such as that on long-term dynamics of lakes, impacts and removal of aquatic invasive species, and human-lake interactions, 2) providing opportunity and training for students, including more than 100 undergraduates spending significant time at the station (e.g., publication of 21 graduate student theses, and direct contact with more than 1250 elementary school students - including more than 200 Native Americans - since 2004) and 3) providing outreach to the general public, including community participation in developing scenarios of the future of the Northern Highland Lake District, presentations to community groups, and a strong presence in the local, state, and national print, radio, and television media. The addition of this new facility will allow the Station to continue to serve as a national and international resource for research and outreach on aquatic resources and their interactions with terrestrial systems and society.

Understanding populations that undergo fluctuations in abundance from one year to the next continues to challenge ecologists. This study will investigate midges in Lake Mývatn, Iceland, to determine why their abundance fluctuates over 5 orders of magnitude in irregular cycles lasting 4-7 years. Juvenile midges feed on algae at the bottom of the lake, and experiments that encompass a full peak-to-peak midge cycle will be initiated to test the hypothesis that the extreme midge fluctuations are caused when the larvae consume all the algae. The research will also investigate the consequences of the midge cycles. During high midge years, over 300 metric tons of midges are deposited in the surrounding heathland, providing food for predators and nutrients for plants. This provides a natural experiment to test hypotheses about how the lake and shoreline ecosystems interact by observing how the pulses of midges ramify through the ecosystem networks.

The research will strengthen international collaborations with scientists in Iceland. It will train US graduate and undergraduate students doing work at Mývatn, providing them exposure to challenging scientific questions whose answers require expertise from several disciplines. Students will work in both aquatic and terrestrial habitats under the tutelage of an interdisciplinary and international research group.

Dramatic 'outbreaks' of organisms - locusts, lemmings, insects - draw public attention to the natural world, in part because scientists do not completely understand the causes for these population surges. This study will investigate midges in Lake Mývatn, Iceland, and why their abundance fluctuates over 4 orders of magnitude in irregular cycles lasting 4-7 years. Adult midges that emerge from the lake die on shore. During high-midge years, the weight of midges that are deposited in the surrounding heathland is equivalent to 10 humpback whales, providing food for predators and scavengers, nutrients for plants, and the basis for local agriculture. By synthesizing results from field samples and experiments over several population cycles, this project promises new insights into fundamental scientific questions about the causes and consequences of population outbreaks. The project will engage graduate and undergraduate students who will work at Mývatn each summer, providing them exposure to extreme biology as well as to educational diversity, as they work in both the lake and on the shoreline under the tutelage of an interdisciplinary group of scientists. The public will learn more about midge outbreaks through an ongoing 'Smidge of Midge' blog.

Ecosystems that show huge changes through time can reveal the ecological forces that stabilize or destabilize natural dynamics. This project involves both long-term data collection in aquatic and terrestrial systems and targeted experiments to test specific hypotheses. The aquatic data collection will build and expand on an existing database that dates back to the 1970s. The project has added weekly monitoring of many additional variables, including midge larvae density, benthic primary production, and pelagic nutrients. The collection of terrestrial data has continued with the monitoring of midge infall and arthropod communities along transects around the lake that were established in 2008. A suite of targeted experiments will address a wide range of research questions such as (i) the role that midges play as ecosystem engineers, changing benthic conditions to favor large-bodied epibenthic cladocerans over small-bodied infaunal species, (ii) the mutualistic effect that midge larvae have on algal growth, and (iii) the importance of midge adults for the flowering of carnivorous plants. These experimental projects are led by graduate students as part of their PhD theses, and by undergraduate interns as independent projects. This combination of aquatic and terrestrial experiments together with regular sampling will test hypotheses about how the lake and shoreline ecosystems are linked together. The research will examine whether the instability of the lake ecosystem could drive instability of the surrounding ecosystem on land.

Researchers at the University of Wisconsin Trout Lake Station conduct year-round research on lakes in northern Wisconsin, sampling frozen or near freezing waterbodies for at least six months out of the year. Trout Lake Station is a long-time contributor and leader of winter lake research efforts internationally and prides itself on providing an inclusive size selection of high-quality winter safety gear and hands-on training to researchers entering the field. While the expertise and equipment at Trout Lake Station can accommodate additional winter research, training, and outreach; the station lacks a heated workspace where people can escape the freezing temperatures, work to develop new lake sampling technologies, and where existing gear can be properly stored and serviced. Through the construction of a heated year-round research workshop, Trout Lake Station will increase its research and outreach capacity both seasonally and spatially.

The Winter Instrumentation Limnology Laboratory (WILL) is a ~3,600 sq ft heated multifunctional research outbuilding composed of three main sections: 1) an active gear staging area, 2) a large workshop/toolshop, and 3) a sensor, buoy platform, and limnological gear makerspace. The building will be a stick and frame design with shop heating that maintains workable temperatures throughout all seasons in a north temperate climate. The WILL is proposed to replace an existing 1,200 sqft non-heated tool workshop. It will triple the outbuilding research workspace and complement the existing 11,200 sqft laboratory and conference building. The winter research user base for TLS stretches beyond the UW-Madison campus, and includes the Wisconsin Department of Natural Resources (WDNR), the National Ecological Observatory Network (NEON) staff and scientists, Global Lakes Ecological Observatory Network (GLEON) researchers, Lake Superior National Estuary Research Reserve (LSNERR), and regional universities. Trout Lake Station aims to become a hub that connects water interest groups in the region. Increasing year-round capacity and providing heated workshop space will strengthen links and collaborations between regional partners. For more information, see https://limnology.wisc.edu/trout-lake-station-welcome/.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.