Introduction to the Marine Algae: Overview 11
cellulose plates. In the typical dinoflagellates, these plates generally form a bi-partite armor, consisting of
an upper anterior half and a posterior half, separated by a grove known as cingulum where the transversal
flagellum is located (Barsanti and Gualtieri 2014).
The organisms of this phylum are important components of the microplankton of marine and
freshwater systems. Some are parasites in invertebrates; others are endosymbiotic (zooxanthellae)
of typical corals. Some are notorious for nuisance blooms and toxin production and many exhibit
bioluminescence (Graham et al. 2009).
The Miozoa possess chlorophyll a, b, and c, α carotene, and various xanthophylls and phycobilins.
The principal reserve polysaccharide is starch granules, but some genera also have oil droplets. These
organisms have a haplontic sexual life cycle and some produce resting stages, called dinoflagellate cysts
or dinocysts (Bold and Wynne 1985).
Cercozoa (Chlorarachniophyceae)
The members of this phylum are naked uninucleated cells that form a net-like plasmodium. Cercozoa is
a small group of algae that occur in temperate and tropical marine waters, growing among sand grains,
on mud, in tidepools, on seaweeds, or in plankton. They are typically mixotrophic, ingesting bacteria and
smaller protists as well as conducting photosynthesis (Graham et al. 2009).
The Cercozoa only include few genera. They possess chlorophyll a and b. The reserve polysaccharide
is paramylon, β-1,3-glucan. The reproduction is predominately asexual by cell divisions or zoospore
formation. Sexual reproduction is reported for two species. The basic life cycle comprises ameboid,
coccoid, and flagellate cell stages (Barsanti and Gualtieri 2014).
Distribution and major communities
Algae are very important organisms, especially in aquatic ecosystems constituents of both, planktonic
and benthonic systems.
Phytoplankton
The phytoplankton is composed of autotrophic and auxothrophic organisms that float freely and
let themselves be carried by water movement. It is widely distributed in the marine and freshwater
environments and is probably the best studied and known group of algae that can be even studied with
satellite images. It plays a key role in the primary production and marine food chains (Whittaker and Likens
1975) and is crucially dependent on minerals such as nitrate, phosphate or silicic acid, whose availability
is governed by the proximity of land and rivers and the balance between the so-called biological pump
and the upwelling of deep, nutrient-rich waters. Many phytoplankton species also depend on organic
water-soluble molecules that they can’t synthesize like vitamin B. Since large areas of the world ocean
are devoid of B vitamins, this limitation could be important for phytoplankton growth and for efficiency
of carbon and nitrogen fixation in those regions (Sañudo-Wilhelmy et al. 2014; Bertrand et al. 2015).
The phytoplankton is dominated by unicellular forms but also includes some colonial and filamentous
organisms (South and Whittick 1987), ranging in size from the smaller forms named picoplankton
0,2–2 µm, to nanoplankton 2–20 µm and up to macrophytoplankton, of 2 mm (Sournia 2008). The
Sargasso Sea, which covers an area of about 4,000 km in diameter, is the only situation in which relatively
large macroalgae, similar in everything to their benthic counterparts, have a planktonic life. Important
constituents of phytoplankton are the coccolithophores (Haptophyta), the cyanobacteria, the euglenoids
(Euglenophyta), the diatoms (Bacillariophyceae), the dinoflagellates (Dinophyceae), and reproductive
stages of Chlorophyceae and Phaeophyceae.
Smayda (1980) reviewed the distribution and succession of phytoplankton species in the marine
environment and concluded that, in general, the cold, nutrient rich (eutrophic) waters are dominated by
diatoms and cyanophytes (Bacillariophyceae and Cyanophyceae), while in warm and oligotrophic waters
cellulose plates. In the typical dinoflagellates, these plates generally form a bi-partite armor, consisting of
an upper anterior half and a posterior half, separated by a grove known as cingulum where the transversal
flagellum is located (Barsanti and Gualtieri 2014).
The organisms of this phylum are important components of the microplankton of marine and
freshwater systems. Some are parasites in invertebrates; others are endosymbiotic (zooxanthellae)
of typical corals. Some are notorious for nuisance blooms and toxin production and many exhibit
bioluminescence (Graham et al. 2009).
The Miozoa possess chlorophyll a, b, and c, α carotene, and various xanthophylls and phycobilins.
The principal reserve polysaccharide is starch granules, but some genera also have oil droplets. These
organisms have a haplontic sexual life cycle and some produce resting stages, called dinoflagellate cysts
or dinocysts (Bold and Wynne 1985).
Cercozoa (Chlorarachniophyceae)
The members of this phylum are naked uninucleated cells that form a net-like plasmodium. Cercozoa is
a small group of algae that occur in temperate and tropical marine waters, growing among sand grains,
on mud, in tidepools, on seaweeds, or in plankton. They are typically mixotrophic, ingesting bacteria and
smaller protists as well as conducting photosynthesis (Graham et al. 2009).
The Cercozoa only include few genera. They possess chlorophyll a and b. The reserve polysaccharide
is paramylon, β-1,3-glucan. The reproduction is predominately asexual by cell divisions or zoospore
formation. Sexual reproduction is reported for two species. The basic life cycle comprises ameboid,
coccoid, and flagellate cell stages (Barsanti and Gualtieri 2014).
Distribution and major communities
Algae are very important organisms, especially in aquatic ecosystems constituents of both, planktonic
and benthonic systems.
Phytoplankton
The phytoplankton is composed of autotrophic and auxothrophic organisms that float freely and
let themselves be carried by water movement. It is widely distributed in the marine and freshwater
environments and is probably the best studied and known group of algae that can be even studied with
satellite images. It plays a key role in the primary production and marine food chains (Whittaker and Likens
1975) and is crucially dependent on minerals such as nitrate, phosphate or silicic acid, whose availability
is governed by the proximity of land and rivers and the balance between the so-called biological pump
and the upwelling of deep, nutrient-rich waters. Many phytoplankton species also depend on organic
water-soluble molecules that they can’t synthesize like vitamin B. Since large areas of the world ocean
are devoid of B vitamins, this limitation could be important for phytoplankton growth and for efficiency
of carbon and nitrogen fixation in those regions (Sañudo-Wilhelmy et al. 2014; Bertrand et al. 2015).
The phytoplankton is dominated by unicellular forms but also includes some colonial and filamentous
organisms (South and Whittick 1987), ranging in size from the smaller forms named picoplankton
0,2–2 µm, to nanoplankton 2–20 µm and up to macrophytoplankton, of 2 mm (Sournia 2008). The
Sargasso Sea, which covers an area of about 4,000 km in diameter, is the only situation in which relatively
large macroalgae, similar in everything to their benthic counterparts, have a planktonic life. Important
constituents of phytoplankton are the coccolithophores (Haptophyta), the cyanobacteria, the euglenoids
(Euglenophyta), the diatoms (Bacillariophyceae), the dinoflagellates (Dinophyceae), and reproductive
stages of Chlorophyceae and Phaeophyceae.
Smayda (1980) reviewed the distribution and succession of phytoplankton species in the marine
environment and concluded that, in general, the cold, nutrient rich (eutrophic) waters are dominated by
diatoms and cyanophytes (Bacillariophyceae and Cyanophyceae), while in warm and oligotrophic waters