Cyanobacterial harmful algal blooms (CHABs) are a growing problem worldwide due to inadequate protections for freshwater resources, poor land management, and in some cases global climate change. Toxins and biomass produced by CHABs present challenges for drinking water production, inhibits use of lakes and rivers for recreation, and alters food web dynamics. This is problematic since in the United States more than 60% of drinking water is produced from freshwaters while recent studies show an increasing number of lakes and rivers are becoming eutrophic, thus capable of supporting CHABs.CHAB species produce a fascinating number of secondary metabolites that display various activities in eukaryotic cells. While some are explored for their medicinal purposes others are acutely toxic affecting multiple organs including liver, kidney, reproductive, central and peripheral nervous systems. In particular, cyanobacteria produce a variety of linear and circular peptides that vary widely in their potency and physiological effects. Among these, microcystins and nodularin are well known inhibitors of protein phosphatases causing acute and chronic effects in the liver. Other cyanopeptides including anabaenopeptins, cyanopeptolins, microginins, and aeruginosins inhibit multiple enzymes in eukaryotic cells, primarily serine/threonine proteases. Originally considered non-toxic recent studies indicate some of these are potent neurotoxins. The temporal and spatial distribution of cyanopeptide mixtures in CHABs is relatively unknown. CHAB forming species are known to produce multiple cyanopeptide classes in laboratory cultures. Thus it is likely that CHAB events involve multiple toxic and/or bioactive compounds rather than a single toxin. This has important implications for human and environmental health as well as public health monitoring strategies. We have described the spatial and temporal dynamics of cyanopeptides in lakes distributed globally and their removal during drinking water treatment processes. Our results challenge the notion that CHAB events involve a single toxin, but rather involve a complex mixture of compounds whose effects on mammalian cells is relatively unexplored.

Todd Miller holds a doctorate in Marine Estuarine Environmental Science from the University of Maryland - College Park where he studied organic sulfur metabolizing bacteria (Roseobacter species) associated with marine algae (dinoflagellates). Following graduate school Dr. Miller was a post- doctoral fellow at Johns Hopkins Bloomberg School of Public Health where he studied the fate of antibacterial compounds Triclosan and Triclocarban in estuarine sediments, biodegradation of anthropogenic compounds by bacteria, and genomics of the dioxin degrading bacterium Sphingomonas wittichii. Following Johns Hopkins he did a second post- doctoral fellowship at the University of Wisconsin - Madison at the Center for Limnology and Department of Bacteriology where he studied the ecology of toxic cyanobacteria in freshwater lakes. He is currently an associate professor in the Joseph J. Zilber School of Public Health at the University of Wisconsin - Milwaukee and an affiliate with the School of Freshwater Sciences. His laboratory studies microbial ecology, and environmental chemistry of hazardous bacteria, chemicals, and natural products in aquatic environments.