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Several genera of Cyanobacteria live in Iowa’s surface waters. Based on more than a decade of lake monitoring by the Iowa Department of Natural Resources and the Iowa State University Limnology Laboratory, the most common genera of Cyanobacteria found in Iowa lakes are Anabaena, Aphanizomenon, Microcystis, and Oscillatoria. Anabaena forms linear colonies of circular cells that resemble a strand of pearls. Aphanizomenon also forms linear colonies but individual cells are not as well defined. Colonies can gather into mats that have a “hairy” appearance. Microcystis clusters into irregularly shaped colonies of small circular cells. Microcystis can form very dense blooms. Oscillatoria forms linear colonies that appear flat and smooth and that are arranged in large mats. (Descriptions from Komárek 2003; Komárek et al. 2003).

Toxins can be produced by several genera of Cyanobacteria commonly found in Iowa (see table below). All Cyanobacteria can produce compounds, known as lipopolysaccharides, that irritate the skin and cause rashes. Anatoxins and saxitoxins target the nervous systems and cause rapid death (within 30 minutes of exposure) by respiratory arrest in mouse bioassays. Saxitoxins are responsible for paralytic shellfish poisoning resulting from consumption of contaminated shellfish. Cylindrospermopsin causes liver damage by blocking protein synthesis. Cylindrospermopsis, one genus that produces this toxin, is an invasive species in Iowa. Different varieties of microcystin can be produced by many of the Cyanobacteria commonly found in Iowa. Microcystins bind to protein enzymes resulting in liver damage. Liver-damaging toxins, such as microcystin, are more commonly produced worldwide than neurotoxins. (Toxin information from Domingos et al. 1999; Sivonen and Jones 1999; Oudra et al. 2001; Carey et al. 2007; Lindon and Heiskary 2009).

Toxin1 Target organ in mammals Cyanobacterial genera commonly found in Iowa2
Anatoxin-a Nervous system Anabaena, Aphanizomenon, and Oscillatoria
Cylindrospermopsins Liver3 Aphanizomenon and Cylindrospermopsis
Lipopolysaccharides (LPS) Potential irritant; affects any exposed tissue All genera
Microcystins Liver Anabaena, Aphanocapsa, Coelosphaerium, Gloeotrichia, Microcystis, Oscillatoria, and Psuedoanabaena
Saxitoxins Nervous system Anabaena, Aphanizomenon, Cylindrospermopsis, and Lyngbya
  1. Each toxin can have several structural variants
  2. Not produced by all species of the particular genus
  3. Cells of toxic species can cause widespread tissue damage, including kidney and lymphoid tissue damage

Source: Domingos et al. 1999; Sivonen and Jones 1999; Oudra et al. 2001; Carey et al. 2007; Lindon and Heiskary 2009