The nuisance species Didymosphenia geminata is thought to have been spread by humans across North and South America and New Zealand. This diatom is of interest for its ability to form thick benthic mats in streams, altering ecosystem properties. Little is known, however, about its historic distribution and the parameters that are associated with its growth in absence of human influence. Although it is considered to be native to Arctic regions, its status at lower latitudes is uncertain. We measured the concentration of D. geminata cells in a sediment core from Beauty Lake, WY, a record that dates back to the Late Pleistocene. From approximately 11,233–8750 years before present (ybp), a Didymosphenia maximum persisted, with peak concentrations of 3774±20 valves/mg dry sediment (9985 ybp). The period corresponded to low flux of Al, Fe, and P within the sediments, supporting the importance of low P in controlling distribution. Furthermore, we demonstrate that D. geminata arrived in Beauty Lake shortly after deglaciation of the watershed. This species arrived without the aid of human introduction, implying an inherent ability for dispersal. We also examined the sediment record of nearby Yellowstone Lake, WY for the presence of D. geminata during the same time interval, but cells were not detected. The Yellowstone caldera is composed of rhyolite, a rock rich in silica (Si) and modest amounts of P. We conclude that both watersheds were exposed to the potential colonization by D. geminata, but just as the North Island of New Zealand has not been able to support this diatom because of P concentrations exceeding a threshold, the Yellowstone watershed is not able to support it either.
Bibliographical noteFunding Information:
We thank Ian Bishop for discussions on the life history of Didymosphenia geminata. Anna Hermann and Genevieve Gaffigan provided laboratory preparation of slides and microscopic observations at INSTAAR, University of Colorado. Susan O?Ney, National Park Service, Grand Teton National Park encouraged the SAS to complete this work and the inclusion of the Yellowstone Lake record. Clive Devoy performed the Psenner extractions at the University of Maine Sawyer Environmental Chemistry Laboratory. Bailey Simmons-Brown performed the SEM and EDS analyses at the School of Earth and Climate Sciences, University of Maine. We thank Ed Theriot for archiving sediment from the Yellowstone Lake Core at the National Lacustrine Core Facility (LacCore), and LacCore for providing material.
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- Didymosphenia geminata
- Late Pleistocene
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