Part F | 33.2
790 Part F Marine Derived Metabolites
ters. Dinoflagellates mostly fall prey to small animals,
such as small crustaceans and fish larvae, and to other
protists, including other dinoflagellates. Dinoflagellates
are common and widespread. As they are so plentiful, they cover a large size range and fulfill so many
different ecological roles. They are a very important
source of food for many other marine organisms. Both
nontoxic and toxin-producing species of dinoflagellates
are present. Algae include cyanobacteria, dinoflagellates, diatoms, raphidophytes, haptophytes, and various
other species, many of which produce potent toxins.
The primary sources of toxins have been identified as
dinoflagellates, bacteria, and blue-green algae. About
7580% of toxic phytoplankton species are dinoflagellates [33.4]. The high abundance blooms of these toxic
phytoplankton species are named harmful algal blooms
(HABs). HABs causing red discoloration of water are
commonly known as red tides [33.5, 6]. It is known
that certain HAB species can produce potent toxins
that impact human health through the consumption of
contaminated shellfish, coral reef fish, and finfish, or
through water or aerosol exposure [33.7]. Around the
world, marine algal toxins cause more than 60 000 poisoning events annually with an associated mortality
rate of 1:5%. It is reported that algal toxins result in
more than 50 000500 000 intoxication incidents per
year, with an overall mortality rate of 1:5% on a global
basis [33.8]. Poisoning caused by the ingestion of
toxin-containing foods has been a part of mankind’s existence and concern for centuries. Most harmful species
have a restricted distribution pattern but some harmful
species have a worldwide distribution [33.5, 6].
Dinoflagellates are the major group producing toxins in the marine ecosystem that impact humans [33.7,
9]. Under specific circumstances more than 40 species
of dinoflagellates and diatoms are known to produce
phycotoxins (marine toxins) [33.10]. Dinoflagellates
are responsible for producing a wide variety of toxins
that accumulate through marine food chains. The biogenetic process by which the toxins accumulate in fish
and shellfish was explained by the food chain. Marine
biotoxins, usually produced by phytoplanktons during
harmful algal blooms, are some of the most potent toxins in the world and are extremely dangerous. For some
toxins, doses at a microgram per kilogram level are
more than sufficient to kill a human. When enough toxins are accumulated in fish or shellfish, small amounts
of cooked or raw tissue can kill a human. For example,
recorded harmful algal blooms have produced enough
PSP toxin in mussels that the consumption of one or
two small mussels could killed a normal, healthy adult
human. While some toxins are very potent, i. e., only
small amounts are required to produce illness or to
bring death, other less potent toxins may accumulate to
such high levels that they can still cause harm. Some dinoflagellates produce compounds that cause death only
when they are extracted and injected into laboratory animals, usually mice.
In the past few decades, extensive studies have
been devoted to the toxicology and pharmacology of
dinoflagellate toxins [33.11]. Dinoflagellate toxins are
structurally and functionally diverse, and many show
unique biological activities. Phycotoxins can accumulate in various marine species such as fish, crabs, or
filter feeding bivalves (shellfish) such as mussels, oysters, scallops, and clams. In shellfish, toxins mainly
accumulate in the digestive glands without causing adverse effects on the shellfish itself. However, when
substantial amounts of contaminated shellfish are consumed by humans, this may cause severe intoxication
of the consumer. The human intoxications known so
far have been associated with mollusc consumption.
The toxic manifestation that develops after ingestion
of seafood contaminated with toxic dinoflagellates is
best known of all due to their most violent form of
poisoning.
This chapter concentrates on the dinoflagellate
species found in marine waters, whose toxins can cause
human poisoning. The major seafood poisoning syndromes caused by toxins have been identified to come
from the dinoflagellates: paralytic shellfish poisoning
(PSP), neurotoxic shellfish poisoning (NSP), diarrheic
shellfish poisoning (DSP), and ciguatera fish poisoning
(CFP). Besides these well-known types of poisoning,
several new poisoning syndromes resulting from newly
appearing dinoflagellate toxins, such as AZAs, YTX,
and PTX have been reported and characterized recently (Table 33.1), and this has increased global public
concerns regarding dinoflagellate associated toxins. Dinoflagellate toxins can be functionally categorized as
neurotoxins and hepatotoxins, according to their clinical symptoms.
790 Part F Marine Derived Metabolites
ters. Dinoflagellates mostly fall prey to small animals,
such as small crustaceans and fish larvae, and to other
protists, including other dinoflagellates. Dinoflagellates
are common and widespread. As they are so plentiful, they cover a large size range and fulfill so many
different ecological roles. They are a very important
source of food for many other marine organisms. Both
nontoxic and toxin-producing species of dinoflagellates
are present. Algae include cyanobacteria, dinoflagellates, diatoms, raphidophytes, haptophytes, and various
other species, many of which produce potent toxins.
The primary sources of toxins have been identified as
dinoflagellates, bacteria, and blue-green algae. About
7580% of toxic phytoplankton species are dinoflagellates [33.4]. The high abundance blooms of these toxic
phytoplankton species are named harmful algal blooms
(HABs). HABs causing red discoloration of water are
commonly known as red tides [33.5, 6]. It is known
that certain HAB species can produce potent toxins
that impact human health through the consumption of
contaminated shellfish, coral reef fish, and finfish, or
through water or aerosol exposure [33.7]. Around the
world, marine algal toxins cause more than 60 000 poisoning events annually with an associated mortality
rate of 1:5%. It is reported that algal toxins result in
more than 50 000500 000 intoxication incidents per
year, with an overall mortality rate of 1:5% on a global
basis [33.8]. Poisoning caused by the ingestion of
toxin-containing foods has been a part of mankind’s existence and concern for centuries. Most harmful species
have a restricted distribution pattern but some harmful
species have a worldwide distribution [33.5, 6].
Dinoflagellates are the major group producing toxins in the marine ecosystem that impact humans [33.7,
9]. Under specific circumstances more than 40 species
of dinoflagellates and diatoms are known to produce
phycotoxins (marine toxins) [33.10]. Dinoflagellates
are responsible for producing a wide variety of toxins
that accumulate through marine food chains. The biogenetic process by which the toxins accumulate in fish
and shellfish was explained by the food chain. Marine
biotoxins, usually produced by phytoplanktons during
harmful algal blooms, are some of the most potent toxins in the world and are extremely dangerous. For some
toxins, doses at a microgram per kilogram level are
more than sufficient to kill a human. When enough toxins are accumulated in fish or shellfish, small amounts
of cooked or raw tissue can kill a human. For example,
recorded harmful algal blooms have produced enough
PSP toxin in mussels that the consumption of one or
two small mussels could killed a normal, healthy adult
human. While some toxins are very potent, i. e., only
small amounts are required to produce illness or to
bring death, other less potent toxins may accumulate to
such high levels that they can still cause harm. Some dinoflagellates produce compounds that cause death only
when they are extracted and injected into laboratory animals, usually mice.
In the past few decades, extensive studies have
been devoted to the toxicology and pharmacology of
dinoflagellate toxins [33.11]. Dinoflagellate toxins are
structurally and functionally diverse, and many show
unique biological activities. Phycotoxins can accumulate in various marine species such as fish, crabs, or
filter feeding bivalves (shellfish) such as mussels, oysters, scallops, and clams. In shellfish, toxins mainly
accumulate in the digestive glands without causing adverse effects on the shellfish itself. However, when
substantial amounts of contaminated shellfish are consumed by humans, this may cause severe intoxication
of the consumer. The human intoxications known so
far have been associated with mollusc consumption.
The toxic manifestation that develops after ingestion
of seafood contaminated with toxic dinoflagellates is
best known of all due to their most violent form of
poisoning.
This chapter concentrates on the dinoflagellate
species found in marine waters, whose toxins can cause
human poisoning. The major seafood poisoning syndromes caused by toxins have been identified to come
from the dinoflagellates: paralytic shellfish poisoning
(PSP), neurotoxic shellfish poisoning (NSP), diarrheic
shellfish poisoning (DSP), and ciguatera fish poisoning
(CFP). Besides these well-known types of poisoning,
several new poisoning syndromes resulting from newly
appearing dinoflagellate toxins, such as AZAs, YTX,
and PTX have been reported and characterized recently (Table 33.1), and this has increased global public
concerns regarding dinoflagellate associated toxins. Dinoflagellate toxins can be functionally categorized as
neurotoxins and hepatotoxins, according to their clinical symptoms.