Diatom Ecology and Evolution
Diatoms, single celled eukaryotic algae, are prolific in almost all bodies of water – from the smallest puddle to the oceans. Aside from being prolific, their silica cell wall allows for them to be preserved in sediments that collect in lake and ocean basins. I study ancient and modern diatoms from the level of populations up to how they fit into ecosystems at large. At the population level, I am interested in how diatoms are dispersed, their sexual cycle, and how they evolve; at the community level, I am interested in the interplay of community assembly and extirpation; and, at the ecosystem level, I am interested in what diatoms can tell us about long-term ecosystem dynamics and landscape evolution.
Scanning electron micrograph of a diatom. Micrograph by Trisha Spanbauer & Jeffery Stone.
Testing the pH of Lago Umayo. Photo by Joe Holmquist.
Ecological Resilience Theory
My interests in long-term ecosystem dynamics led to my participation in an NSF IGERT group on resilience and adaptive management. Often, in the paleoecological record we see abrupt community reorganization driven by environmental change. This led me to use sedimentary diatom records to test ecological resilience theory, generally the quantitative analysis of early warning signals. These studies have shed light on rapid community reorganization prior to regime shifts. This work has led to collaborations with wildlife managers, federal agencies, and scientists at international universities. Moving forward, I have been collaborating with ecologists, geoscientists, and physicists on novel ways of characterizing stability, transients, and chaos in ecological records.
Novel Approaches in Paleolimnology
Being committed to understanding ecological processes over periods of time often not captured in the historical record, I have interests in how lakes operate as archives of biological and chemical changes within the catchment. Further, I am interested in new theoretical and methodological approaches to the study of paleolimnology. For instance, I have begun a new project using ancient DNA (aDNA) and next-generation molecular analysis to understand the rapid evolution of an endemic diatom. In addition, advances in the application of aDNA will allow paleolimnologists to reconstruct communities of organisms that leave no visually identifiable remains within sediments.
Collecting a plankton tow from Lake Titicaca. Photo by Joe Holmquist.