Marine Dinoflagellate-Associated Human Poisoning 33.4 Algal Blooms and Red Tide Dinoflagellates 793
Part F | 33.4
which resulted in its name (night light), but the reaction is now known to occur in several marine species.
Many organisms in the ocean emit such light, although
dinoflagellates are the only photosynthetic organisms
capable of this behavior [33.33]. It is widely accepted
that dinoflagellates account for much of the planktonic
bioluminescence in the ocean [33.34]. The dinoflagellates begin to glow, which is often seen in the waves of
the ocean on a moonless night, but will brighten considerably when disturbed, such as in the wake of a ship.
33.3.5 Toxicity
As they are biochemically diverse, they vary in photosynthetic pigments and toxin production ability. The
taxonomy of harmful dinoflagellates was reviewed by
Taylor et al. [33.35]. A number of dinoflagellate species
are known to produce potent neurotoxins, which are often associated with the phenomena commonly called
red tide. These outbreaks are now called HABs. Documentation of HABs has expanded greatly over the
last few decades, and at present, nearly every country with marine waters is known to be affected by
these blooms [33.36]. HAB toxins can affect humans,
other mammals, seabirds, fish and many other animals and organisms. One major category of impact
occurs when toxic species are filtered from the water
as food by shellfish, which then accumulate the algal
toxins to levels that can be lethal to humans or other
consumers.
33.4 Algal Blooms and Red Tide Dinoflagellates
Of the 5000 marine algal species, 300 have a high
proliferation rate, resulting in high dense algal clouds
called blooms. Algal bloom is due to species that quite
innocently cause coloring of seawater. It is their photosynthetic pigments that can tint the water during
blooms. These blooms may discolor the sea to various shades of brown, orange, purple, yellow, or red.
Red tide gets its name from the phenomenon by which
pigmented phytoplankton reproduce to such a high concentration that it turns the water red or dark brown.
This can be misleading because nontoxic algae can also
cause this to happen. With the hope of clarifying this,
the scientific community has uses the term HAB for
toxic red tides. Dinoflagellate blooms (red tides) are
regular seasonal phenomena occurring in some part of
the world. Blooms of toxic algae are known as HABs.
The most common type of HAB is referred to as a red
Tide because the bloom discolors the water, making it
appear red. However, HABs may also be yellow, orange, brown, green, white, or pink, depending on which
one of the three primary types of phytoplankton is responsible for the problem; dinoflagellate, diatoms, or
blue-green algae.
Dinoflagellates are perhaps best known as causing HABs. Although the dinoflagellates responsible for
most red tides are comparatively simple organisms,
some have the ability to synthesize potent toxins as
by-products of metabolism. Among the most effective
poisons known, these toxins may affect nearby marine
life if ingested, or may even indirectly poison humans
through the food chain. The detrimental effects of HAB
can range from cell and tissue damage to organism
mortality, and can be caused by a number of mechanisms, including toxin production, predation, particle
irritation, induced starvation, and localized anoxic conditions. As a result, a bloom may affect many living
organisms of the coastal ecosystem, from zooplankton
to fish larvae to people. Other harmful algal blooms produce toxins with no identifiable effects on humans but
devastating impacts on coastal living resources. For example, the flagellate Heterosigma akashiwo is thought
to produce an ichthyotoxin that kills fish [33.37], resulting in significant threats to penned fish in mariculture
operations. Dinoflagellate blooms can also cause massive killing of fish and shellfish, often causing significant economic damage.
At least 90 species of marine microalgae are known
to produce toxins. Of these species, 70 are dinoflagellates [33.38]. The effects of HABs on aquatic organisms have been reviewed by [33.39]. Red tides
occur in all marine regions with a temperate or warmer
climate. Sometimes the dinoflagellates involved with
red tides synthesize toxic chemicals. Red tide is due
to certain species of dinoflagellates that contain neurotoxins. Toxic dinoflagellates (Pyrrhophyta, Desmophyceae, and Dinophyceae), for example, numbered 22
known species in 1984 [33.40], but increased to 59
species a little more than a decade later [33.41]. Blooms
of dinoflagellates produce red tides, which injure marine life. Dinoflagellates’ algal blooms create red tides,
which can release strong neurotoxins, such as STX,
which can be ingested by shellfish and passed on to
humans who eat the infected shellfish. These toxins
have been responsible for incidents of wide-scale death
Part F | 33.4
which resulted in its name (night light), but the reaction is now known to occur in several marine species.
Many organisms in the ocean emit such light, although
dinoflagellates are the only photosynthetic organisms
capable of this behavior [33.33]. It is widely accepted
that dinoflagellates account for much of the planktonic
bioluminescence in the ocean [33.34]. The dinoflagellates begin to glow, which is often seen in the waves of
the ocean on a moonless night, but will brighten considerably when disturbed, such as in the wake of a ship.
33.3.5 Toxicity
As they are biochemically diverse, they vary in photosynthetic pigments and toxin production ability. The
taxonomy of harmful dinoflagellates was reviewed by
Taylor et al. [33.35]. A number of dinoflagellate species
are known to produce potent neurotoxins, which are often associated with the phenomena commonly called
red tide. These outbreaks are now called HABs. Documentation of HABs has expanded greatly over the
last few decades, and at present, nearly every country with marine waters is known to be affected by
these blooms [33.36]. HAB toxins can affect humans,
other mammals, seabirds, fish and many other animals and organisms. One major category of impact
occurs when toxic species are filtered from the water
as food by shellfish, which then accumulate the algal
toxins to levels that can be lethal to humans or other
consumers.
33.4 Algal Blooms and Red Tide Dinoflagellates
Of the 5000 marine algal species, 300 have a high
proliferation rate, resulting in high dense algal clouds
called blooms. Algal bloom is due to species that quite
innocently cause coloring of seawater. It is their photosynthetic pigments that can tint the water during
blooms. These blooms may discolor the sea to various shades of brown, orange, purple, yellow, or red.
Red tide gets its name from the phenomenon by which
pigmented phytoplankton reproduce to such a high concentration that it turns the water red or dark brown.
This can be misleading because nontoxic algae can also
cause this to happen. With the hope of clarifying this,
the scientific community has uses the term HAB for
toxic red tides. Dinoflagellate blooms (red tides) are
regular seasonal phenomena occurring in some part of
the world. Blooms of toxic algae are known as HABs.
The most common type of HAB is referred to as a red
Tide because the bloom discolors the water, making it
appear red. However, HABs may also be yellow, orange, brown, green, white, or pink, depending on which
one of the three primary types of phytoplankton is responsible for the problem; dinoflagellate, diatoms, or
blue-green algae.
Dinoflagellates are perhaps best known as causing HABs. Although the dinoflagellates responsible for
most red tides are comparatively simple organisms,
some have the ability to synthesize potent toxins as
by-products of metabolism. Among the most effective
poisons known, these toxins may affect nearby marine
life if ingested, or may even indirectly poison humans
through the food chain. The detrimental effects of HAB
can range from cell and tissue damage to organism
mortality, and can be caused by a number of mechanisms, including toxin production, predation, particle
irritation, induced starvation, and localized anoxic conditions. As a result, a bloom may affect many living
organisms of the coastal ecosystem, from zooplankton
to fish larvae to people. Other harmful algal blooms produce toxins with no identifiable effects on humans but
devastating impacts on coastal living resources. For example, the flagellate Heterosigma akashiwo is thought
to produce an ichthyotoxin that kills fish [33.37], resulting in significant threats to penned fish in mariculture
operations. Dinoflagellate blooms can also cause massive killing of fish and shellfish, often causing significant economic damage.
At least 90 species of marine microalgae are known
to produce toxins. Of these species, 70 are dinoflagellates [33.38]. The effects of HABs on aquatic organisms have been reviewed by [33.39]. Red tides
occur in all marine regions with a temperate or warmer
climate. Sometimes the dinoflagellates involved with
red tides synthesize toxic chemicals. Red tide is due
to certain species of dinoflagellates that contain neurotoxins. Toxic dinoflagellates (Pyrrhophyta, Desmophyceae, and Dinophyceae), for example, numbered 22
known species in 1984 [33.40], but increased to 59
species a little more than a decade later [33.41]. Blooms
of dinoflagellates produce red tides, which injure marine life. Dinoflagellates’ algal blooms create red tides,
which can release strong neurotoxins, such as STX,
which can be ingested by shellfish and passed on to
humans who eat the infected shellfish. These toxins
have been responsible for incidents of wide-scale death