You’ve probably seen it – slimy mats of brownish green clinging to rocks in streams or on lake beds – and perhaps not given it another thought. But thankfully for the sake of our environment; George Mason University’s College of Science Assistant Professor Rosalina Stancheva Christova has.

Christova has been researching Microcoleus, a common mat-forming cyanobacterium found in streams and lakes worldwide, for more than 20 years. The troublesome thing about Microcoleus is, that while some strains pose a risk to human, animal, and aquatic ecosystem health ; curiously, others do not. Christova wanted to learn more about Microcoleus in George Mason University’s backyard – the Shenandoah River. To do so, she reached out to a colleague at UVA Wise, A. Bruce Cahoon, who shared her interest in the same research. Together, Christova and Cahoon aimed to study the species diversity, distribution, and toxicity of this cyanobacterium in the Shenandoah.
4-VA approved their Collaborative Research Grant proposal, Integrative Characterization of the Anatoxin-a-Producing Benthic Cyanobacterial Genus Microcoleus in the Shenandoah River, and Christova and Cahoon got to work. The research was protracted and laborious, but proved successful and surprising – revealing a stunning breakthrough in identification of Microcoleus collected from the river.
Explains Christova, “The genome of the common and abundant mat-forming taxon, morphologically most similar to Microcoleus lacustris, was sequenced by our team from field material. Phylogenomic evidence demonstrates that this taxon represents a species new to science and should be classified within the genus Limnofasciculus.”
In all, they identified six species and isolated two monoclonal strains, one non-toxic and one producing anatoxin-a. “Phylogenetic analyses based on 16S rRNA gene sequences confirmed that both strains belong to the genus Microcoleus. The toxic strain was most closely related to M. anatoxicus from California, confirming the wide distribution of this problematic cyanobacterium,” says Christova.
The breakthrough and all the associated research didn’t come easily, beginning with the collection of the benthic mats over a two-year period from 11 sites in the North and South Forks of the Shenandoah River.

Samples from field sites

Christova credits her large team for doing the good, yet, difficult work. She was supported by Benoit Van Aken (who as her co-PI) and Pat Gillevet, both of George Mason University. Involved in the project were graduate student Jacob Mormando – who collected a sample with novel Limnofasciculus species for genome analysis and conducted temperature experiments with the toxic Microcoleus strain; Sydney Brown – who handled molecular and morphological studies of the species, field work collecting benthic cyanobacteria from the river, molecular work and cyanobacteria culturing; and Rwan Alsaadi – who developed distributional and ecological data and field work collecting benthic cyanobacteria from the river.
Undergraduate students also played a role in the effort – Armon Ghaffari did data analysis of Microcoleus distribution in the river samples and Emma Boyden oversaw the laboratory maintenance of cyanobacterial cultures. Two undergrads at UVA Wise, Amelia Clark and Matthew Sullivan, prepared molecular work.
Additionally, Janice Lawrence and Cecilio Valadez-Cano, of the University of New Brunswick, Canada, helped with the molecular studies.
Another important collaborator on the project was Gordon M. Selckmann, Associate Director for Aquatic Habitats at Interstate Commission on The Potomac River Basin (ICPRB). The 4-VA team used some of the field material Selckmann collected as part of an ongoing investigation of the benthic harmful algal blooms in the Shenandoah River funded by the Virginia Department of Environmental Quality and ICPRB.

In the Lab: L to R, Alsaadi, Brown, Mormando, Cahoon and Christova
With the groundbreaking work behind them, they are now sharing their findings, including at the Society for Freshwater Science Annual Meeting, the Southeastern Phycological Colloquy, the Potomac River Conference, and the Biennial Coastal & Estuarine Research Federation Meeting, organized by Selckmann.

Concludes Christova, “The 4-VA@Mason funding was very important to me, as it supported the establishment of my research lab, fostered the development of regional and international research collaborations, and provided funding for undergraduate and graduate students interested in aquatic and cyanobacterial research.”

























