Diatoms of North AmericaEvelyn Gaiser, Florida International University
THIRTY-SIX YEARS OF THINKING LIKE A DIATOM: THE POWER OF PERSISTENT ATTACHMENTS
As an incoming master’s student at Iowa State in 1989, I tried to enroll in Lakeside’s summer Limnology course but it had already filled, so I was encouraged to take the diatom course instead. That twist of fate changed the course of my career and that of many students who have since come through my lab and the Lakeside course. In this presentation, I will reflect on my experience in Dr. Charlie Reimer’s last summer of teaching “Ecology and Systematics of Diatoms” and how it influenced my career. In teaching us how to “think like a diatom” Dr. Reimer encouraged us look at and draw living diatoms, exposing us not only to their incredibly diverse appearances but also the myriad of ways that diatoms associate with each other, their substrates, and other microbes. This approach caused me to notice epizoic diatoms on cladocerans in Lake West Okoboji, that became the subject of my M.S. thesis and continues to motivate my research on benthic mat-dwelling diatoms. Research in my lab has shown that mat-dwelling diatoms often produce copious mucilage that promotes facilitative interactions with bacteria to access limiting nutrients, protects them from harmful UV light, and provides moisture during drought. In essence, the mechanism that allows diatoms to attach themselves to others sustains them through stressful conditions. In a similar way, I’ve been attached to Lakeside Lab for 36 years through my own research on diatoms and through my students who have also trained and taught there. We have formed persistent attachments to the place of Iowa Lakeside Lab and to other diatomists that has provided career-sustaining expertise and inspiration and life-sustaining friendships and collaborations.
Jeffery Stone, Indiana State University
REVISITING THE DIATOM RECORD OF FOY LAKE, MONTANA
In 2001, we collected a ~14,000-year sediment core from the deepest basin of Foy Lake, Montana. From this record, we analyzed multiple paleolimnologic indicators, including diatoms, sediment chemistry, charcoal, stable isotopes, and pollen. Fossil diatom samples were analyzed from approximately 2,000 continuous intervals, making it one of the longest high-resolution diatom records ever collected. Over the past 20+ years, parts of this diatom record, which originally was the centerpiece of my dissertation have been published, but some aspects remain as untold stories. In this talk, I will explore some of the published highlights from this record and discuss elements have haven’t been presented before, along with some new ideas about how this record could be explored more completely based on things I have learned since I first learned to identify diatoms at the Iowa Lakeside Laboratory in 2000 – the final year that Gene Stoermer led the diatom summer course.
David Burge,
LAKESIDE DIATOMS – THE NEXT GENERATION
After many years of being a student, TA, researcher, and visiting lecturer, David co-taught the Lakeside Ecology and Systematics of Diatoms class in 2024. This talk will highlight his ideas and dreams for the next generation of Lakesiders.
Victoria Chraïbi, Tarlton College
FITTING FRUSTULES INTO THE FUTURE OF UNDERGRADUATE EDUCATION
Public undergraduate education in the United States is undergoing multiple concurrent transitions that present challenges and opportunities for the study of diatoms. Master’s programs are being phased out at many universities in preference for PhD programs, leading to a baccalaureate-to-PhD pipeline that requires students to fulfill heightened expectations for research and publication while an undergraduate. At the same time, the transition from face-to-face teaching to online and asynchronous learning limits hands-on experience in laboratory and field skills. Summer field courses that used to be a staple of environmental education programs compete with students completing core classes, holding full-time jobs, and providing familial support. To our benefit, diatoms present multifaceted research opportunities that span scientific disciplines, lab and field settings, technologies, budget sizes, and learned skills. Ensconcing undergraduate opportunities for research in coursework offers opportunities to include service-learning, community outreach, and collaborative investigation. How can we, the diatomist community, benefit from modern technologies that enable long-distance collaborations, produce diatom educational materials, remove barriers to participation, and mentor the new generation of diatom experts?
Jane Marks, University of Northern Arizona
ECOSYSTEM CONSEQUENCES OF A NITROGEN FIXING PROTO-ORGANELLE
Microscale symbioses can be critical to ecosystem functions, but the nutrient dynamics of these interactions in nature are often cryptic. We used stable isotopic tracers and nanoSIMS imaging to quantify the phenology of nitrogen (N) and carbon (C) dynamics of a three-member symbiosis that supports a salmon-bearing river food web within a naturally assembled epiphytic microbiome over its summertime succession. After winters with riverbed-scouring floods, the macroalga Cladophora glomerata uses nutrients in spring runoff to grow streamers >10 meters long. During summer flow recession, N inputs wane and Cladophora becomes densely epiphytized by three species of Epithemia, diatoms with N-fixing endosymbionts descended from a free-living cyanobacterium. During epiphyte succession on Cladophora, N fixation rates increased as Epithemia spp. became dominant, and total C fixation rates of assemblages declined. At the microscale, Cladophora C-fixation declined to near zero, while Epithemia C-fixation increased. The shift in C-fixation from Cladophora to Epithemia results in a tenfold increase in C transfer to grazing caddisflies. In response to demand for N, the diatom allocates high levels of newly fixed C to the endosymbiont. Consequently, these proto-organelles have the highest rate of C and N accumulation in this tripartite symbiosis during the biologically productive season, and one of the highest rates of N fixation reported for any river ecosystem.
Lowe, Rex, University of Wisconsin, Center for Limnology and Bowling Green State University
HOCHUNK BOILING SPRINGS AND STAR WARS
The boiling springs of Pheasant Branch Conservancy in Madison Wisconsin had sustained the Hochunk Indian nation for hundreds of years. The springs also support a diatom flora that is rich in numbers, but poor in species representation. In this report, I will discuss the importance of this ecosystem, both two native Americans, and of course to diatoms dominated by morphologically diverse Meridion circulare. What does this have to do with Star Wars? Stay tuned.
