Scientific Assessment of Freshwater Harmful Algal Blooms.
Lopez, CB et al. (2008) Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health of the Joint Subcommittee on Ocean Science and Technology. Washington, DC.
Freshwater harmful algal blooms (HABs) are comprised of algae that either create health hazards for humans or animals through the production of toxins or bioactive compounds or that cause deterioration of water quality through the build-up of high biomass, which degrades aesthetic, ecological, and recreational values. While freshwater HABs occur naturally, human actions that disturb ecosystems in the form of increased nutrient loadings and pollution, modified hydrology, and introduced species have been linked to the increased occurrence of some freshwater HABs. The majority of the freshwater HAB problems reported in the United States and worldwide are due to one group of algae, the cyanobacteria HABs (CyanoHABs), but other groups of algae can also be harmful. CyanoHABs are not a new phenomenon, but the frequency and geographic distribution of documented CyanoHABs seem to have dramatically increased in recent decades in the United States and globally. The issue of freshwater HABs has received more attention outside the United States in the past, but, as most U.S. states now experience freshwater HABs, the issue is of growing national concern.
Freshwater HAB toxins can have a broad range of negative impacts on humans, animals, and aquatic ecosystems. Many cyanobacteria can produce neurotoxic, hepatotoxic, dermatotoxic, or other bioactive compounds, and blooms of toxigenic cyanobacteria pose a particular threat if they occur in drinking water sources. The World Health Organization has issued an advisory limit for drinking water of 1 μg L-1 for microcystin-LR, one of the most common cyanobacterial toxins, but no Federal regulations exist in the United States. The U.S. Environmental Protection Agency (EPA) has listed selected cyanobacteria and their associated toxins on the Contaminant Candidate List. EPA will use this process to determine whether it should regulate these contaminants in the future.