Didymosphenia geminata (Rock Snot) in the City Watershed – Factors that Affect the Growth, Spatial Distribution, and Timing of the Didymo Bloom in the (2010-2012) Isabella Oleksy1; Amalia Handler2; David Richardson2; Cathy A. Gibson3, Timothy J. Hoellein4, David B. Arscott5, Laura Achterberg6, Emily Bialowas7, Amalia M. Handler8, Andrea Miller9, Molly Redfield10 University of , Durham, NH1; State University of New York at New Paltz, New Paltz, NY2, Skidmore College, Saratoga Springs, NY3; Loyola University, Chicago, IL4; Stroud Water Research Center, Avondale, PA5, University of Nebraska, Lincoln, NE6; Cornell University, Ithaca, NY7; Franklin & Marshall College, Lancaster, PA8; Unity College, Unity, ME9; Mount Holyoke College, South Hadley, MA10 What is didymo? Spatial, Longitudinal, and Temporal Patterns • Single-celled Figure 1. Conductivity is • When in bloom, grows in thick mats significantly lower at UP1 Figure 2. Didymo % coverage of the with large amounts of extra-cellular than at all other sites along stream bottom for 2010-2012 polysaccharide stalks stream (a). Nitrate compared to didymo cell densities • Native to northern hemisphere in concentrations were highest for 2011 & 2012. Maximum cell low nutrient, mountainous streams at UP1 and fairly stable at densities in 2012 were at least 2 • Recent nuisance blooms in northern downstream locations (b). orders of magnitude higher in 2012 hemisphere, and an invasive species in This is interesting because than in 2011. The blooms in 2010 Didymo mats in Esopus, 2012. New Zealand UP1 was the only site across were comparable in distribution all 3 years to be free of and magnitude to 2012. In 2011 How does it spread? didymo. Sulfate the peak of the bloom occurred at •Fishing (esp. felt •Tubing concentrations were similar UP2 while in 2012 the bloom grew soled waders) • In the Catskills: in 2010 and 2011, but longitudinally. •Hiking Hurricane Irene significantly lower in 2012 •Boating stream (c). remediation Didymo diatom magnified 100x. Figure 3. The relationships between Figure 4. Flashy flow total P (TDP + particulate P), AFDM conditions in 2011 (F(1,93) = 384.5, p < 0.001), AFDM.P kept didymo in check, Study Questions: (F(1,93) = 71.7, p < 0.001)and Dry but even a week Mass and cell density (F = 342.5, 1. What is the extent of the bloom in Ashokan Reservoir watershed? (1,93) without rain caused a p = 0.001) for all 2011 and 2012 spike in cell densities. 2. What causes differences in cell densities along Esopus Creek? data. Although P in the water Steady flow conditions 3. What locations may be vulnerable to didymo blooms in the future? column is scarce, these figures in 2012 allowed the suggests that didymo extracts and blooms grow thicker. bioaccumulates P, most likely They experienced a Methods through a mechanism in the stalk natural die-back in late • Weekly sampling at 7 sites on the material of the mats . summer. upper Esopus creek • Water chemistry analysis Conclusions (conductivity, pH, temp) • Frequent flood events kept didymo blooms in check during Summer 2011 • Hydrology (discharge, velocity) • Birch creek high conductivity could account for large bloom above the Shandaken tunnel. This sudden rise in conductivity is most likely • Rock scrapings and % coverage caused by a wastewater treatment plant and ski mountain located upstream. • • H O cell counting method Anthropogenic activity is still the main driver of the spread of didymo in the Catskills Figure. 1. Three sites located above (UP1-3) and 2 2 • All Esopus tributaries except Birch Creek were didymo-free in 2011; in 2012 it was found in Warner Creek and Stony Clove Creek. Further four sites below (DOWN2-3,5-6) “the portal,” • Total Dissolved Phosphorus (Murphey an inflow of water from a tunnel connected to education for the public and government agencies is necessary. Informational sign posts needed near popular recreation spots in tributaries the Schoharie Reservoir and Riley 1962) to prevent further spread. Left: Rock • Continued monitoring is necessary to gain a better understanding of the nuisance alga. scraping at field Acknowledgements: We thank National Science Foundation Research Experience for Undergraduates grants to site. SUNY New Paltz for funding assistance, and the University of New Hampshire. We thank Nate Rigolino, Michael Sandstrom, Andrew Jacobs, and Michelle Webber for field assistance. We thank Don Hodder for help with Right: Estimating printing and field logistics. Lastly we thank Ashokan Watershed Stream Management Program for funding, discharge in Esopus Creek. providing valuable information and assistance the past three summers and for organizing the Catskill Environmental Research and Monitoring conference.