Poisonous Plants, Fungi, and Algae

1. Poisonous Plants, Fungi, and Algae Algal Toxins

2. Algal Blooms and Harmful Algal Blooms

3. Kingdom Monera • Cyanobacteria- blue green algae • Used as a food source: Nostoc, Spirulina (since ancient times - today protein additive) • Toxins produced by several species can cause problems during blooms

4. Kingdom Protista • Six divisions of algae: • Division Pyrrophyta - dinoflagellates • Division Chrysophyta - diatoms • Division Euglenophyta - euglenoids • Division Chlorophyta - green algae • Division Rhodophyta - red algae • Division Phaeophyta - brown algae

5. Toxic Cyanobacteria • Normally algal cells only release the toxins when the cells die or when they age and become leaky • Poisoning typically occurs when animals ingest whole cells • If water is treated to break up a bloom, it is possible for fatal levels of the toxin to be released • 12 genera of cyanobacteria known to be toxin-producers. • Two of the most toxic - Anabaena and Microcystis.

6. Types of toxins • Two groups of deadly toxins in the cyanobacteria • Neurotoxins - alkaloids - nervous systems • Anatoxins - Very Fast Death Factor – 4 min – bind to acetylchone receptors and cause respiratory paralysis • Saxitoxins – neurological dysfunction and paralysis – block sodium channels on neurons – (also in some dinoflagellates) • Hepatotoxins - cyclopeptides - target the liver • Microcystins – disrupt cytoskeleton in liver cause liver cells to collapse – blood pools in liver causing fatalities – may also be carcinogenic • Other less deadly toxins – swimmers itch

7. Anabaena • Anabaena - a genus of filamentous N2-fixing cyanobacteria • Known for producing a suite of cyanotoxins which range from the neurotoxic anatoxins and saxitoxins to the hepatotoxic microcystins. • Genus can be found throughout the world

8. Anabaena

9. Microcystis • Microcystis spp. are single-celled, colonial, freshwater cyanobacteria • World-wide distribution • Microcystins (hepatotoxins) are main toxin type • M. aeruginosa and M. viridis appear to be the most common microcystin-prodcuing species.

10. Microcystis

11. Dinoflagellates • Unicellular algae covered with cellulose plates giving an armored appearance • Important to the food chain in marine and fresh water • Some marine species cause Red Tides • Bloom conditions • Color the water “red” • Produce powerful toxins • Pfiesteria newly recognized problem

12. Dinoflagellates

13. Dinoflagellates and Red Tides • Several species of dinoflagellates, especially Gymnodinium breve, Alexandrium spp, produce powerful toxins that can cause massive fish kills • As schools of fish swim through a bloom, the dinoflagellates may be disrupted or killed, releasing neurotoxins into the water • The toxins damage the gills or suppress heart rate and result in asphyxiation - hundred or thousands of dead fish wash up on beaches

14. Other Problems • In other instances, the toxins accumulate in various filter feeding shellfish • When the shellfish are eaten the toxins can affect humans • Cause various syndromes depending on the dinoflagellate and type of toxin

15. Dinoflagellate Poisonings • Paralytic Shellfish Poisoning (PSP) – saxitoxin • Diarrhetic Shellfish Poisoning (DSP) • Neurotoxic Shellfish Poisoning (NSP) – usually only fish kills • Ciguatera Fish Poisoning (CFP) – GI, neurological, and cardiovascular symptoms from eating contaminated fish (fish not affected) • Pfiesteria piscicida – recently identified problem

16. Pfiesteria piscicida • Pfiesteria piscicida implicated as the organism responsible for recent fish kills and fish disease • Since the early 1990s toxins produced by Pfiesteria may have killed over one billion fish in North Carolina alone with other outbreaks along east coast • Toxins not identified yet • People exposed to toxins have developed skin and neurological problems

17. Pfiesteria • Complex life cycle • Appears to be around 24 different stages in the life cycle – with flagellated, amoeboid, and encysted stages • Only 3 stages appear to form toxins