Flow Imaging Microscopy Blog

INSTAAR, University of Colorado

University_of_Colorado_1Investigation of diatoms: population dynamics and life cycles using the FlowCAM®
Submitted by: Sarah Spaulding , INSTAAR, University of Colorado

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One of our projects at INSTAAR, University of Colorado, is the investigation of the life cycle of diatoms, especially of the species Didymosphenia geminata. Diatoms are unique organisms for their external silica cell wall and their unusual life cycle. As diatom cells divide through vegetative division, they get smaller over time. At some point, usually at about 40% of their maximum size, an environmental factor (light, temperature or nutrient concentration) can trigger sexual reproduction, with formation of gametes and then expansion of an auxospore. The auxospore results in restoring the maximum size of the population – so they can get small again.

Ian Bishop, M.S. student in Environmental Studies at CU, is gaining new insight into the diatom life cycle for his research. Ian collects D. geminata colonies at monthly intervals from South Boulder Creek and measures thousands of cells using the FlowCAM. He is able to compare the shape of the cell sizes of a large population against model expectations. The results of this work are showing not only the timing of size regeneration in natural populations, but the differences between mainstem river and spring habitats. Ultimately, we expect to understand how the life cycle of D. geminata is related to its success as a nuisance and invasive species.

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Hannaea

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Ian Bishop collects D. geminata from S. Boulder Creek

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Ian collecting D. geminata covered rocks from under winter ice

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Ian explaining methods for size series analysis using the FlowCAM to INSTAAR graduate students

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Plot showing the valve length and frequency of A. minutissimum, H. baicalensis and D. geminata using the FlowCAM from Spaulding et al. 2012. Automated measurement of diatom size. Limnology and Oceanography Methods 10: 882-890

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Topics: Freshwater Research, Marine Research, Aquatic Research, User Spotlight