Sustaining aquatic ecosystems under global change requires scientific knowledge working in collaboration with ecosystem management and society. This session will focus on key areas of scientific knowledge and management collaboration driven forward by the career of noted aquatic ecologist Steve Carpenter. Each talk will focus on one research topic, and discuss how Carpenter’s work contributed to our current knowledge and explore key future directions for research in this area. Research areas will include: trophic cascades, aquatic food webs, freshwater fisheries management, ecosystem manipulations, eutrophication and phosphorus as a slow variable, scenario development, working with decision-makers, and resilience.
Note: We are requesting a longer-than-normal session to accommodate strong interest in this session and our desire to have invited speakers on particular topics while retaining space for those who wish to request to be included with contributed talks. Each talk will be 15 minutes in length.
We also have additional speakers who cannot be listed below due to limitations of the form. All are tentatively confirmed:
Garry Peterson, Stockholm Resilience Centre, Stockholm University. The Resilience of Aquatic Ecosystems: Thinking creatively about the future
Peter Leavitt, Department of Biology, University of Regina. Variance as an ecosystem property: Lessons learned from long-term data
Steve Carpenter, University of Wisconsin. Closing speaker: Models, Experiments, Scenarios and Resilience Thinking.
Lead Organizer: Elena M. Bennett, McGill University (elena.bennett@mcgill.ca)
Co-organizers:
Emily Stanley, University of Wisconsin (ehstanley@wisc.edu)
Jim Elser, Flathead Lake Biological Station, University of Montana (jim.elser@flbs.umt.edu)
Presentations
02:00 PM
Serious fun: The limnological legacy of SRC (8071)
Primary Presenter: Jim Elser, University of Montana (jim.elser@umontana.edu)
Among the many things we can thank Steve Carpenter for is his view that, whatever you are doing in science, it should be fun, at least most of the time. This talk will reflect on the several decades of science fun I have had with SRC in a saga that encompasses not just my junior-year biometry homework (not fun) but also a stint as a semi-clueless undergraduate researcher (pretty fun) and as a rookie technician as the Cascade Project got underway (super fun, including the generation of data that led me into the field of ecological stoichiometry). This was followed by the fun but challenging period during which I transitioned to independent researcher performing SRC-inspired whole-lake experiments in California and Canada. Later, as I began work on phosphorus sustainability, Steve’s innovative mind led me back for collaborations involving application of an autoregressive change point model and a general autoregressive conditional heteroskedasticity model (spoiler alert: not 100% fun). Such sustained observations lead to one conclusion, made with strong confidence: working with Steve is serious fun. (Note: some of the fun will also be reviewed.)
02:15 PM
MANAGING FOR RESILIENT FRESHWATER FISHERIES UNDER GLOBAL CHANGE (7752)
Primary Presenter: Gretchen Hansen, University of Minnesota (ghansen@umn.edu)
Freshwater ecosystems and fisheries are experiencing unprecedented rates of change from multiple stressors, including climate change and land-use change. Successful management under these conditions requires identification of key levers that can maintain fisheries within the safe operating space. Here, we provide a framework for managing freshwater fisheries for resilience under environmental change across multiple scales based on two examples. First, we describe a passive adaptive management experiment for understanding drivers of and potential management responses to ongoing walleye declines in northern Wisconsin lakes. We assess the evidence for management effectiveness in these lakes following multiple years of management interventions relative to reference systems. Second, we developed landscape models of resilience of coldwater fish habitat to climate change and watershed development under the safe operating space context. We describe the development and application of these models to prioritize protection of coldwater habitat under warming conditions. Local actions can influence freshwater fish responses to global change and facilitate adaptation and restoration of valued fisheries, but knowing how, when, and where management is likely to be effective requires a commitment to science-based management and resilience thinking. Collectively, these examples highlight the depth and breadth of the influence of Dr. Steve Carpenter’s approach to fisheries science and resilience thinking and the widespread influence of his career on freshwater fisheries management.
02:30 PM
Steve Carpenter and The Cascade Project (7729)
Primary Presenter: Michael Pace, University of Virginia (mlp5fy@virginia.edu)
Since the early 1980s Steve Carpenter has a led team of researchers in a series of whole lake manipulation studies collectively called the Cascade Project. Important contributions from this work include the findings that: 1) strong predatory-prey interactions propagate through food webs and influence primary productivity, 2) food web structure can limit production across a wide nutrient loading gradient, 3) terrestrial organic carbon supports lake foods, 4) ecosystems approaching thresholds exhibit warnings, and 5) ecological resilience is measurable by the duration of states. Carpenter employed two primary research strategies in conducting this work. The first involved creating whole lake experiments to set up sharp contrasts. Manipulations included top-predator removals, plantivorous fish additions, curtaining of lakes, additions of inorganic nutrients, additions of carbon stable isotopes, and lake darkening. These ambitious manipulations mostly worked but occasionally went awry with unintended consequences for which Carpenter coined the term “expect surprise!” A second research strategy was developing models related to the lake manipulations. These models informed: hypotheses, experimental design, data analysis, and syntheses of key ideas. Carpenter’s models were rarely just the elaboration of equations but instead were tightly strung to data. The Cascade Project was successful because the program addressed important, general questions and because of strong collaborations. Team members shared common goals, worked hard, spent time together, and felt their contribution to the enterprise. The effectiveness of these teams was not an accident but part of Carpenter’s ability to, not only see scientific frontiers, but also motivate others and help them succeed.
02:45 PM
Analysis of long-term data to understand food web dynamics - Carpenter's cascade and the spring clear water phase (8198)
Primary Presenter: Lars Rudstam, Cornell University (lgr1@cornell.edu)
Long term data and their analyses are critical for understanding ecosystem dynamics and importance of invasive species. Many years ago, I was a postdoc with Steve Carpenter on the Lake Mendota biomanipulation project. The analysis of these data showed the importance of the specific Daphnia species on the seasonality of the spring clear-water phase which in turn depended on fish abundance. Since then, I have studied similar phenomena using another long-term data set from Oneida Lake, New York, studies heavily influenced by Carpenter. Although clear-water phase in the past was also the result of fish-Daphnia-phytoplankton dynamics, the clear water phase was primarily affected by zebra and quagga mussels after their invasion in early 1990s. Further, the replacement of zebra with quagga mussels by 2009 changed the seasonality and extent of the clear water phase as quagga mussels are active at lower temperature and build up higher biomass than zebra mussels. For this polymictic lake, benthic grazers dominate and species-specific difference in the two dominant benthic grazers matters. Generalizing among lakes need to include benthic grazers and their ability to access the water column which is affected by temperature stratification. Fro example, although zebra mussels are now in one of Steve’s favorite lakes – Lake Mendota – they are likely to be less important compared to Oneida Lake due to summer stratification and low oxygen conditions. In a stratified lake in New York with low summer oxygen, Daphnia remained the main driver of clear water phase even after the invasion of zebra and quagga mussels.
03:00 PM
WHAT DOES RESILIENCE LOOK LIKE IN WORKING AQUATIC LANDSCAPES? (8299)
Primary Presenter: Daniel Schindler, University of Washington (deschind@uw.edu)
Resilience has become a foundational concept in efforts to understand how ecosystems respond to stressors and maintain flows of goods and services to people. A principal goal of modern conservation and restoration is often to protect and restore resilience. Despite its broad conceptual appeal, it is not clear that ecologists know what resilience looks like in objective and practical terms. I will provide a series of case studies from the salmon-producing rivers of western Alaska to highlight the remarkable diversity of space and time scales at which ecological variation is expressed in response to changes in climate. It is the complexity associated with the hierarchical expression of spatial and temporal variation that is ultimately critical for sustaining commercial and subsistence fisheries, and maintaining fish-wildlife interactions. A major challenge for watershed management and restoration is to develop robust strategies for dealing with ongoing climate change and its effects on aquatic ecosystems. A common approach is to advance prescriptive management plans based on specific forecasts of future ecosystem states or environmental conditions. This approach is likely prone to failure as our ability to forecast future responses of ecosystems is distinctly limited, particularly when considering the complexity associated with the hierarchical structure of ecosystems. An alternative approach is to focus on protecting and restoring the processes that generate heterogeneity in watersheds and ultimately produce the ‘options’ rivers and their biota have for reorganizing and adapting to ongoing climate change and other regional stressors.
TR02A - From Phosphorus to Fish: Celebrating the Free-ranging Career of Steve Carpenter
Description
Time: 2:00 PM
Date: 5/6/2024
Room: Lecture Hall