Bob Sterner has had an outsized influence on limnology, aquatic sciences, and ecology more broadly. From his early research on consumer resource competition and nutrient regeneration to his classic tome with Elser on ecological stoichiometry, his insightful and creative perspectives have changed the way that we see ecological interactions in lakes, oceans, and indeed all ecosystems, including some that are not even wet! Bob has always been fascinated by phytoplankton and his early work focused on the reciprocal ways that phytoplankton affect herbivores via food quality and that herbivores influence phytoplankton via effects on the availability of nitrogen and phosphorus. That phytoplankton thread has continued to the work he is doing today to understand some of the drivers of increasing cyanobacterial blooms globally, paradoxically even in some of the least productive systems on the planet such as Lake Superior. Ecological stoichiometry has always been at the center of Bob’s work. Through the direct influence of Dave Tilman and Sue Kilham, as well the classic work of AC Redfield and GE Hutchinson, Bob has fundamentally changed our understanding of the role of organisms and stoichiometry in the ecological realm, whether it be via the impacts of stoichiometric food quality or the drivers that force elemental imbalance in ecological interactions and ecosystems. His work on the latter has been particularly relevant to our understanding of ongoing human influences on lakes.
So let’s hang out, talk about stoichiometry, Daphnia, large and small lakes, chemostats, and whatever but especially let’s share some stories about Bob, and celebrate what has been an impactful career!
Lead Organizer: Jim Elser, University of Montana (jim.elser@umontana.edu)
Co-organizers:
Jim Cotner, University of Minnesota (cotne002@umn.edu)
Presentations
02:00 PM
Sterner, Stoichiometry and Trains (8327)
Primary Presenter: James Cotner, University of Minnesota (cotne002@umn.edu)
It's been a good run, Bob, and I'm happy to have been a part of the Sterner Stoichiometry Express. In this talk I will discuss how we got here and some of the passengers, conductors and engineers that have brought us to this destination in our journey. We are not done yet. but this is a good opportunity to pause, look at where we have been and to consider where we want to go in the future.
02:15 PM
LIMNOLOGY LUMINARY: BOB STERNER'S TRAILBLAZING WORK AND MENTORSHIP IN AQUATIC ECOSYSTEMS (7762)
Primary Presenter: Kaitlin Reinl, Lake Superior National Estuarine Research Reserve (kreinl@wisc.edu)
Bob Sterner has had a significant impact on the field of limnology. His contributions in the area of stoichiometry have been critical to advancing our understanding of organismal interactions. Furthermore, his recent work on cyanobacterial blooms in Lake Superior has led to important science and management implications for the largest freshwater lake in the world. In addition to these admirable contributions to our understanding of aquatic ecosystems, Bob has also been an impactful teacher and adviser during his career. This talk will highlight insights and wisdom that Bob has passed down and celebrate his role as a mentor in addition to his impressive career as a limnologist.
02:30 PM
The role of phosphorus availability on nitrogen cycling: from Great Lakes to urban lakes (8057)
Primary Presenter: Gaston Small, University of St. Thomas (gaston.small@stthomas.edu)
“Phosphorus is the master element that controls the availability of the others.” This idea, first proposed by AC Redfield, has been explored and advanced by Bob Sterner throughout his career. Our previous work with Sterner helped elucidate how differences in phosphorus (P) availability across the Laurentian Great Lakes influenced rates of nitrification and denitrification, allowing for a century-long increase in nitrate in Lake Superior. More broadly, this work suggested that management-driven reductions in P availability can lead to increased accumulation and export of nitrogen (N) in large lakes. Here, we explore how this idea applies to smaller urban lakes, many of which have been actively managed for P at the watershed level (e.g., by lawn P fertilizer restrictions and green stormwater infrastructure) and within lakes (e.g., through alum treatments). We examined temporal trends in urban lakes in the Minneapolis-Saint Paul metropolitan area. Many of these managed lakes have experienced declines in both total P and, to a lesser extent, total Kjeldahl N, resulting in increased water column N:P ratios. Potential ecosystem effects of reduced P availability may include increased downstream N export and decreased N-fixation. Changes in urban lake water nutrient chemistry are mediated by complex interactions between specific management activities, physical properties of the lake and watershed, and climate, but in aggregate, these urban lakes provide a unique laboratory to test hypotheses around ecological stoichiometry and its ecosystem scale impacts in human dominated lakes.
02:45 PM
Hi Bob, is it real? (7876)
Primary Presenter: Jotaro Urabe, Tohoku University (urabe@tohoku.ac.jp)
Thirty years ago, Bob and I did a simple experiment to investigate how the LIGHT-NUTRIENT BALANCE affects secondary production by changing the chemical quality of the primary producers. In that experiment, we found that when the supply of nutrients such as phosphorus was low, high light conditions reduced the growth rate of Daphnia species despite an increase in algal food abundance. We hypothesized that high light and low nutrient supply would reduce daphnia growth rate because the amount of phosphorus relative to carbon in the algal food was low compared to the requirements of daphnia for healthy growth. But was daphnia growth really reduced by a lack of phosphorus? Bob and I wondered if there was a “smart” way to answer this question. One day I learned that Daphnia are good animals because they have the ability to drink water from their anus! So, Bob and I decided that we would use this ability to confirm that the low growth rate of daphnia was due to phosphorus deficiency. Bob and I, along with Jessica Clasen who was a summer student in the Sterner labs at the time, set up experiments in which we immersed daphnia individuals in a solution of highly concentrated phosphorus for a few hours a day to allow them to enjoy anal drink. Here I will talk about how that experiment went and what happened afterwards with some eipsodes on Bob Sterner.
03:00 PM
AN ODE TO BIVARIATE COUPLING: SOME REFLECTIONS ON WHAT I LEARNED FROM BOB STERNER (8303)
Primary Presenter: James Hood, Ohio State University (hood.211@osu.edu)
In celebration of Bob Sterner’s retirement, this talk will summarize some of my reflections on how Bob shaped the way I conduct and teach science. I spent much of the 2000s at the University of Minnesota – Twin Cities under Bob Sterner’s supervision; first as a technician, then as a graduate student. If I learned anything during that period, it was how to plot one variable against another – a bivariate plot. There are examples of these bivariate plots throughout Bob’s publications; scatterplots of the relationship between seston carbon and phosphorus, organismal phosphorus content and body size, even spatial and temporal scales. Bob never stopped at calculating a correlation coefficient or fitting a regression equation. Instead he would encourage us to ponder what the intercept, slope, or even that weird cluster of points off to the right told us about the fundamental processes and rules governing ecological dynamics. For example, if the relationship between log seston carbon and log seston phosphorus has a slope less than one, what can that tell us about how carbon and phosphorus cycles change across productivity gradients? Bob was not the first to use these approaches. As a student of ecological history, he knew how his research built on that of Alfred Redfield, Robert Peters, Jim Brown, and many others. However, the cautious and thoughtful way in which he queried bivariant datasets and combined different approaches (e.g., fieldwork, experiments, and theory) advanced ecology and shaped how I and likely many others conduct and teach science.
03:15 PM
A whistle-stop tour of ecological stoichiometry (8215)
Primary Presenter: Elena Litchman, Carnegie Institution (elitchman@carnegiescience.edu)
Bob Sterner’s ecological stoichiometric thinking has provided fundamental insights into many areas of ecology and evolutionary biology and inspired countless environmental scientists. I will present several vignettes on applying stoichiometric thinking to diverse problems, from ecology to human health, and how we can combine ecological stoichiometry with other disciplines to advance the field. I will also share my favorite pieces of life and career advice from Bob.
TR01A - Bob Sterner: Celebrating A Career Full of Stoichiometry, Lakes of Many Sizes, and Thoughtful Science
Description
Time: 2:00 PM
Date: 3/6/2024
Room: Lecture Hall