aspects of chemical intermediates, target reaction, and target signals; and interfering factors and the ecological consequences of this process.
Cyanobacteria produce and excrete a variety of allelopathic compounds that
affect other Cyanophyta, eukaryotic algae, bacteria, zooplankton, higher plants,
and fish and mammalian cells. These effects are regulated by various abiotic and
biotic conditions, such as nutrient availability, temperature, and light intensity but
also cell density and growth phase of the source cyanobacterial community. The
bioactive metabolites include cyclic peptides, alkaloids, terpenoids, and others
which can have a variety of inhibitory effects on the different target organisms.
Ecological consequences such as declines in biodiversity and accumulation of
toxins in the food chain have been shown. However, most of these compounds
have not yet been fully tested regarding their full range of effects on natural
phytoplankton communities. A detailed elucidation of the influence of
cyanobacterial allelochemicals is of key importance for understanding and managing the succession of natural phytoplankton communities.
Keywords
Cyanobacteria · Allelopathy · Secondary metabolites · Phytoplankton
succession · Chemical ecology
1
Introduction
The seasonal succession of phytoplankton is an annually repeated process of
community assembly in freshwater and marine ecosystems shaped by external
factors and internal interactions. While the role of physical factors, grazing, and
nutrient limitation has been known for long, several ecological interactions have
become research foci more recently, such as overwintering of key organisms, the
microbial food web, parasitism, and higher-order predators. These novel interactions revealed strong effects on species replacements as summarized in a review by
Sommer et al. [1]. One mechanism affecting phytoplankton succession, however,
has still been neglected despite early studies [2, 3] indicating its potential relevance: allelopathy.
The term allelopathy was first introduced by Molisch [4] to describe the process
of ethylene accelerating fruit ripening, as an effect that one plant impacted another
[4]. Rice [5] redefined this term as any direct or indirect effects of compounds
produced and released by plants and microorganisms on other plants (microbes) in
the negative or positive way. In 1996, the International Allelopathy Society (IAS)
further developed this definition into a process involving secondary metabolites
produced by bacteria, fungi, algae, and plants secondary metabolites that impact
biological systems. Allelochemicals are the compounds produced and released by
one organism that directly influences others [6]. Studies investigating allelopathic
effects of terrestrial plants are abundant in the field of agriculture and forestry [7, 8].
However, allelopathic autotrophs are also a well-known phenomenon in aquatic
ecosystems [9].
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Y. Pei et al.
Cyanobacteria produce and excrete a variety of allelopathic compounds that
affect other Cyanophyta, eukaryotic algae, bacteria, zooplankton, higher plants,
and fish and mammalian cells. These effects are regulated by various abiotic and
biotic conditions, such as nutrient availability, temperature, and light intensity but
also cell density and growth phase of the source cyanobacterial community. The
bioactive metabolites include cyclic peptides, alkaloids, terpenoids, and others
which can have a variety of inhibitory effects on the different target organisms.
Ecological consequences such as declines in biodiversity and accumulation of
toxins in the food chain have been shown. However, most of these compounds
have not yet been fully tested regarding their full range of effects on natural
phytoplankton communities. A detailed elucidation of the influence of
cyanobacterial allelochemicals is of key importance for understanding and managing the succession of natural phytoplankton communities.
Keywords
Cyanobacteria · Allelopathy · Secondary metabolites · Phytoplankton
succession · Chemical ecology
1
Introduction
The seasonal succession of phytoplankton is an annually repeated process of
community assembly in freshwater and marine ecosystems shaped by external
factors and internal interactions. While the role of physical factors, grazing, and
nutrient limitation has been known for long, several ecological interactions have
become research foci more recently, such as overwintering of key organisms, the
microbial food web, parasitism, and higher-order predators. These novel interactions revealed strong effects on species replacements as summarized in a review by
Sommer et al. [1]. One mechanism affecting phytoplankton succession, however,
has still been neglected despite early studies [2, 3] indicating its potential relevance: allelopathy.
The term allelopathy was first introduced by Molisch [4] to describe the process
of ethylene accelerating fruit ripening, as an effect that one plant impacted another
[4]. Rice [5] redefined this term as any direct or indirect effects of compounds
produced and released by plants and microorganisms on other plants (microbes) in
the negative or positive way. In 1996, the International Allelopathy Society (IAS)
further developed this definition into a process involving secondary metabolites
produced by bacteria, fungi, algae, and plants secondary metabolites that impact
biological systems. Allelochemicals are the compounds produced and released by
one organism that directly influences others [6]. Studies investigating allelopathic
effects of terrestrial plants are abundant in the field of agriculture and forestry [7, 8].
However, allelopathic autotrophs are also a well-known phenomenon in aquatic
ecosystems [9].
324
Y. Pei et al.