Poisonous Plants,
Fungi, and Algae
Algal Toxins
Algal Blooms and Harmful Algal Blooms
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
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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
Toxic Cyanobacteria
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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 toxinproducers.
Two of the most toxic - Anabaena and Microcystis.
Types of toxins
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Two groups of deadly toxins in the cyanobacteria
 Neurotoxins
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- 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
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- 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
Anabaena
Anabaena - a genus of filamentous N2fixing 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
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Anabaena
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.
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Microcystis
Dinoflagellates
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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
Dinoflagellates
Dinoflagellates and Red Tides
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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
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
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Dinoflagellate Poisonings
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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
Pfiesteria piscicida
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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
Pfiesteria
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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