Cyanobacterial Blooms in the Southeast: Understanding Their Distribution and Management

Abstract

Water is vital for life. The increased demand for freshwater resources dictates that current water practices must ensure access to and availability of high-quality water for future generations. Phytoplankton community structure is indicative of, and can influence, water quality. In freshwater systems, bloom-forming cyanobacteria are the primary group of phytoplankton that dominate nutrient-rich (eutrophic), aquatic habitats. Cyanobacteria can cause noxious blooms and have the potential to produce toxic secondary metabolites. Microcystin, a hepatotoxin associated with many cyanobacterial species, has been linked to the deaths of livestock, fishes and humans. Over 70% of the 89 sites sampled in Alabama during the 2008, 2009, and 2010 summers were classified as “eutrophic” based on chlorophyll concentration, and 90% of sites had detectable levels of the cyanotoxin, microcystin. Given the prevalence of cyanobacteria and their related toxin, microcystin predictive correlation and regression tree (CART) and multiple linear regression models were created for algal, cyanobacterial, and cyanotoxin abundances as a function of chlorophyll (µg/L), phycocyanin (µg/L), and microcystin (µg/L) respectively. The CART models created have the potential to become a powerful tool for both resource managers and citizen scientists. In an effort to understand the processes favoring toxic cyanobacterial blooms, scientists often examine the intraspecific variation of blooms through the use of molecular markers. In the case presented, detection sensitivity for unique isolates was compared using the well-established phycocyanin spacer and a newly described multilocus approach using housekeeping genes. In the population tested, the new approach was able to differentiate all isolates as unique strains.