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