Cross-references
Adaptive Management
Ecosystem-Based Management
Estuarine Habitat Restoration
Fish Assemblages
CYANOBACTERIA
Monia El Bour
Marine Microbiology Unit, Department of Marine
Biotechnology and Biodiversity, National Institute of Sea
Sciences and Technologies (INSTM), Tunis, Tunisia
Synonyms
Blue-green algae
Definition
Cyanobacteria or cyanophyceae (initially known as bluegreen microalgae) are nonmotile and planktonic photosynthetic prokaryotes, belonging to the kingdom
Eubacteria, division of Cyanophyta. They are common
in some extreme environments and occasionally form
dense blooms harmful to estuarine environments.
Introduction
Cyanobacteria (photosynthetic prokaryotes) are the
Earth’s oldest known oxygenic photoautotrophs (Pearl
and Otten, 2013). The fossil records of Schopf et al.
(2000) suggest that cyanobacteria have been present on
earth for at least 3.5 billion years, being distributed
worldwide from polar to equatorial latitudes (Vincent,
2000; Wynn-Williams, 2000). Their proliferation during
the Precambrian era ($3.5 bya) dramatically altered the
previously anoxic biosphere which led to the evolution
of higher terrestrial plant and animal life (Schopf et al.,
2000). Thus, the cyanobacteria group constitutes a large
and morphologically diverse phylum with more than
4,000 isolates and 19 of the most important taxa
(species).
Many genera have the ability to fix atmospheric nitrogen (N 2 ) (through an anaerobic process), while they can
store phosphorus (P) and sequester iron (Fe) and a range
of essential trace metals (Whitton, 2012). These traits
enable them to exploit both nutrient-scarce and nutrientenriched, diverse terrestrial and aquatic environments
worldwide. The cyanobacteria present a range of attributes
that give them, in certain environmental conditions, a clear
competitive growth advantage over planktonic algae, and
therefore they thrive in all kinds of environments
(Gomes et al., 2012). Besides planktonic forms, benthic
cyanobacteria constitute the principal colonizers at the
interface between sediments and water, where they affect
fluid flow dynamics and structure formation (Whitton
and Potts, 2000). Once classified as microalgae, the
cyanobacteria
produce
photosynthetic
pigments
(chlorophyll a and/or other accessory pigments such as
phycocyanin, allophycocyanin, and phycoerythrin)
(Briand et al., 2003).
Here, the status of cyanobacteria in estuarine environments is reviewed, their biological and ecological features,
and roles in primary sedimentary structures. In addition,
the effects of anthropogenic and climate change on
cyanobacteria blooms and toxicities are examined.
Ecobiology of cyanobacteria
Cellular morphological features of cyanobacteria are very
diverse, including spherical, ovoid, and cylindrical unicellular species, as well as multicellular colonial and filamentous forms (Couté et al., 2001). Some species are able to
differentiate specialized cells: (1) heterocysts which are
able to fix nitrogen in water under N-limited conditions;
and (2) akinetes which tolerate stressful conditions such
as periods of high temperature or drought. Cyanobacterial
species are sometimes difficult to identify due to their high
phenotypic plasticity (Briand et al., 2003).
These organisms comprise a unique phylogenetic
group of bacteria that perform oxygenic photosynthesis
(Hackenberg et al., 2011). In addition, cyanobacteria
occupy diverse ecological niches and exhibit enormous
diversity in terms of their habitats, physiology, morphology, and metabolic capabilities (Beck et al., 2012). In fact,
cyanobacteria are able to establish competitive growth in
almost any environment where there is, at least temporarily, water and sunlight (Badger et al., 2006; EstevesFerreira et al., 2013).
The most recent taxonomic classification of
cyanobacteria is based on the so-called polyphasic
approach (Johansen and Casamatta, 2005). In this
approach, molecular phylogenetic analyses are the basic
criteria for classification of genera and species, with the
cytological and morphological markers (synapomorphic
and autapomorphic characters) and the ecology (habitat
preference, life strategy, and ecophysiology) considered
an integral part of the taxonomic definition, with additional important biochemical and molecular markers
(Komarek and Mares, 2012).
Two morphological types are distinguished within the
cyanobacteria group: (1) the filamentous species forming
elongated cell chains (trichomes) often bundled together
(multi-trichomous species); and (2) the coccoid species
forming spheroidal cells often arranged in cell clusters
(Staley et al., 1989; Whitton and Potts, 2000). In estuarine ecosystems, cyanobacteria are primary producers
that use light energy to synthesize organic matter from
mineral nutrients and CO 2 (photosynthesis). Their specific physiologic capabilities enable them to compete
very efficiently with other photosynthetic microorganisms and to regulate their buoyancy (by means of gas
vacuoles). Thus, they can colonize different depths in
the water column depending on the location of nutrients
and availability of light (Klemer et al., 1982; Walsby
et al., 2001).
CYANOBACTERIA
169
Adaptive Management
Ecosystem-Based Management
Estuarine Habitat Restoration
Fish Assemblages
CYANOBACTERIA
Monia El Bour
Marine Microbiology Unit, Department of Marine
Biotechnology and Biodiversity, National Institute of Sea
Sciences and Technologies (INSTM), Tunis, Tunisia
Synonyms
Blue-green algae
Definition
Cyanobacteria or cyanophyceae (initially known as bluegreen microalgae) are nonmotile and planktonic photosynthetic prokaryotes, belonging to the kingdom
Eubacteria, division of Cyanophyta. They are common
in some extreme environments and occasionally form
dense blooms harmful to estuarine environments.
Introduction
Cyanobacteria (photosynthetic prokaryotes) are the
Earth’s oldest known oxygenic photoautotrophs (Pearl
and Otten, 2013). The fossil records of Schopf et al.
(2000) suggest that cyanobacteria have been present on
earth for at least 3.5 billion years, being distributed
worldwide from polar to equatorial latitudes (Vincent,
2000; Wynn-Williams, 2000). Their proliferation during
the Precambrian era ($3.5 bya) dramatically altered the
previously anoxic biosphere which led to the evolution
of higher terrestrial plant and animal life (Schopf et al.,
2000). Thus, the cyanobacteria group constitutes a large
and morphologically diverse phylum with more than
4,000 isolates and 19 of the most important taxa
(species).
Many genera have the ability to fix atmospheric nitrogen (N 2 ) (through an anaerobic process), while they can
store phosphorus (P) and sequester iron (Fe) and a range
of essential trace metals (Whitton, 2012). These traits
enable them to exploit both nutrient-scarce and nutrientenriched, diverse terrestrial and aquatic environments
worldwide. The cyanobacteria present a range of attributes
that give them, in certain environmental conditions, a clear
competitive growth advantage over planktonic algae, and
therefore they thrive in all kinds of environments
(Gomes et al., 2012). Besides planktonic forms, benthic
cyanobacteria constitute the principal colonizers at the
interface between sediments and water, where they affect
fluid flow dynamics and structure formation (Whitton
and Potts, 2000). Once classified as microalgae, the
cyanobacteria
produce
photosynthetic
pigments
(chlorophyll a and/or other accessory pigments such as
phycocyanin, allophycocyanin, and phycoerythrin)
(Briand et al., 2003).
Here, the status of cyanobacteria in estuarine environments is reviewed, their biological and ecological features,
and roles in primary sedimentary structures. In addition,
the effects of anthropogenic and climate change on
cyanobacteria blooms and toxicities are examined.
Ecobiology of cyanobacteria
Cellular morphological features of cyanobacteria are very
diverse, including spherical, ovoid, and cylindrical unicellular species, as well as multicellular colonial and filamentous forms (Couté et al., 2001). Some species are able to
differentiate specialized cells: (1) heterocysts which are
able to fix nitrogen in water under N-limited conditions;
and (2) akinetes which tolerate stressful conditions such
as periods of high temperature or drought. Cyanobacterial
species are sometimes difficult to identify due to their high
phenotypic plasticity (Briand et al., 2003).
These organisms comprise a unique phylogenetic
group of bacteria that perform oxygenic photosynthesis
(Hackenberg et al., 2011). In addition, cyanobacteria
occupy diverse ecological niches and exhibit enormous
diversity in terms of their habitats, physiology, morphology, and metabolic capabilities (Beck et al., 2012). In fact,
cyanobacteria are able to establish competitive growth in
almost any environment where there is, at least temporarily, water and sunlight (Badger et al., 2006; EstevesFerreira et al., 2013).
The most recent taxonomic classification of
cyanobacteria is based on the so-called polyphasic
approach (Johansen and Casamatta, 2005). In this
approach, molecular phylogenetic analyses are the basic
criteria for classification of genera and species, with the
cytological and morphological markers (synapomorphic
and autapomorphic characters) and the ecology (habitat
preference, life strategy, and ecophysiology) considered
an integral part of the taxonomic definition, with additional important biochemical and molecular markers
(Komarek and Mares, 2012).
Two morphological types are distinguished within the
cyanobacteria group: (1) the filamentous species forming
elongated cell chains (trichomes) often bundled together
(multi-trichomous species); and (2) the coccoid species
forming spheroidal cells often arranged in cell clusters
(Staley et al., 1989; Whitton and Potts, 2000). In estuarine ecosystems, cyanobacteria are primary producers
that use light energy to synthesize organic matter from
mineral nutrients and CO 2 (photosynthesis). Their specific physiologic capabilities enable them to compete
very efficiently with other photosynthetic microorganisms and to regulate their buoyancy (by means of gas
vacuoles). Thus, they can colonize different depths in
the water column depending on the location of nutrients
and availability of light (Klemer et al., 1982; Walsby
et al., 2001).
CYANOBACTERIA
169