Species & Toxins
Of the over 2,000 known cyanobacteria species, about 40 genera produce various toxins.
☠️Toxin Categories
Hepatotoxins
Attack the liver
Neurotoxins
Attack the nervous system
Dermatotoxins
Irritate skin and mucous membranes
🔬Key Cyanotoxins
Microcystin
HepatotoxinInhibits protein phosphatases in the liver, leading to cell structure destruction.
- •Nausea, vomiting, diarrhea
- •Abdominal pain
- •Liver damage
- •Possibly carcinogenic
Anatoxin-a
NeurotoxinBinds to acetylcholine receptors, causing overstimulation then blockade.
- •Muscle tremors, cramps
- •Respiratory distress
- •Salivation
- •Rapid death possible
Cylindrospermopsin
Hepato-/CytotoxinInhibits protein synthesis, damages liver, kidneys and other organs.
- •Delayed onset
- •Liver and kidney damage
- •General malaise
Saxitoxin
NeurotoxinBlocks sodium channels, prevents nerve impulse transmission.
- •Numbness
- •Muscle weakness, paralysis
- •Respiratory arrest
📋Guidelines & Limits
| Toxin | Drinking Water (WHO) | Recreational Water | Source |
|---|---|---|---|
| Microcystin-LR | 1 µg/L | 10-20 µg/L | WHO 2020 |
| Cylindrospermopsin | 0.7 µg/L | 6 µg/L | WHO 2020 |
| Anatoxin-a | 30 µg/L | 60 µg/L | WHO 2020 |
| Saxitoxin | 3 µg/L | 30 µg/L | WHO 2020 |
WHO guidelines are recommendations. National limits may vary.
🦠Common Toxin-producing Genera
Microcystis aeruginosa
Freshwater, worldwide
- •Colonial aggregates
- •Floats via gas vesicles
- •Most common bloom former
Anabaena / Dolichospermum
Freshwater, temperate to tropical
- •Filamentous with heterocysts
- •Nitrogen-fixing
- •Multiple toxins
Planktothrix rubescens
Deep, cool lakes
- •Reddish color
- •Mid-depth habitat
- •Can bloom in winter
Nodularia spumigena
Brackish water, Baltic Sea
- •Baltic Sea specialist
- •Forms surface foam
- •Summer blooms
Cylindrospermopsis raciborskii
Originally tropical, spreading north
- •Climate change beneficiary
- •Invasive in Europe
- •Delayed toxicity
Aphanizomenon flos-aquae
Freshwater, worldwide
- •Grass-like flakes
- •Nitrogen-fixing
- •Not all strains toxic
📚 Sources & References
[1] WHO (2020). Cyanobacterial toxins: Microcystins.
[2] Chorus, I. & Welker, M. (2021). Toxic Cyanobacteria in Water, 2nd Edition.
[3] Buratti, F. M. et al. (2017). Cyanotoxins: producing organisms, occurrence, toxicity.