Hi all…in a follow-up study on the Toledo Ohio 2014 Microcystis bloom event which led to a “do not drink advisory” for more than 400,000 residents,researchers have reported that a virus may have been involved in the crisis and they warn that for utilities prone to experiencing such blooms that more stringent raw water monitoring may be necessary. Cell bound cyanotoxins (at least in the case of microcystins and anatoxin-a) usually aren’t released until the cells experience stress or die. As with other bacteria, there exist viruses which can attack cyanobacteria (cyanophage) leading to the release of toxin and if within range of a drinking water intake can be problematic. The study authors documented the viral infection by sequencing RNA from the Toledo water samples and they used computer models to simulate how the cyanobacterial blooms moved through water. They also warn that this scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future.
Bill
Ecophysiological Examination of the Lake Erie Microcystis Bloom in 2014: Linkages between Biology and the Water Supply Shutdown of Toledo
Steffen et al
http://pubs.acs.org/doi/abs/10.1021/acs.est.7b00856
Environ. Sci. Technol. 2017, 51(12), 6745−6755
ABSTRACT: “Annual cyanobacterial blooms dominated by Microcystis have occurred in western Lake Erie (U.S./Canada) during summer months since 1995. The production of toxins by bloom-forming cyanobacteria can lead to drinking water crises, such as the one experienced by the city of Toledo in August of 2014, when the city was rendered without drinking water for >2 days. It is important to understand the conditions and environmental cues that were driving this specific bloom to provide a scientific framework for management of future bloom events. To this end, samples were collected and metatranscriptomes generated coincident with the collection of environmental metrics for eight sites located in the western basin of Lake Erie, including a station proximal to the water intake for the city of Toledo. These data were used to generate a basin-wide ecophysiological fingerprint of Lake Erie Microcystis populations in August 2014 for comparison to previous bloom communities. Our observations and analyses indicate that, at the time of sample collection, Microcystis populations were under dual nitrogen (N) and phosphorus (P) stress, as genes involved in scavenging of these nutrients were being actively transcribed. Targeted analysis of urea transport and hydrolysis suggests a potentially important role for exogenous urea as a nitrogen source during the 2014 event. Finally, simulation data suggest a wind event caused microcystin-rich water from Maumee Bay to be transported east along the southern shoreline past the Toledo water intake. Coupled with a significant cyanophage infection, these results reveal that a combination of biological and environmental factors led to the disruption of the Toledo water supply. This scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future.”
