Temporal Dynamics of Cyanobacterial Bloom Community Composition and Toxin Production from Urban Lakes

With a long evolutionary history and a need to adapt to a changing environment, cyanobacteria in freshwater systems use specialized metabolites for communication, defense, and physiological processes. Furthermore, many cyanobacterial specialized metabolites and toxins present significant human health concerns due to their liver toxicity and their potential impact to drinking water. Gaps in knowledge exist with respect to changes in species diversity and toxin production during a cyanobacterial bloom (cyanoHAB) event; addressing these gaps will improve understanding of impacts to public and ecological health. In the current report we detail community and toxin composition dynamics during a late bloom period. Species diversity decreased at all study sites over the course of the bloom event, and toxin production reached a maximum at the midpoint of the event. We also isolated three new microcystins from a Microcystis dominated bloom (1-3), two of which contained unusual doubly homologated tyrosine residues (1 and 2). This work provokes intriguing questions with respect to the use of allelopathy by organisms in these systems and the presence of emerging toxic compounds that can impact public health.