12 Marine Macro- and Microalgae: An Overview
(poor in nutrients), the coccolithophores predominate. Dinoflagellates are abundant in both situations.
The cyanobacteria are most commonly found in tropical and/or subtropical environments (Round 1981).
Benthic algae
The benthic algae comprise micro- and macroalgae and both groups are more abundant on rocky shores.
In general, the multicellular benthic macroalgae are commonly called seaweeds because of their size,
construction, and attachment to firm substrata (Dawes 1988). Because they require a stable substrate for
attachment and light, they are confined to marginal areas of continents and islands, where they occupy a
relatively narrow range and some seamounts with tops near the surface (Ramos et al. 2016).
The macroalgae comprise the largest and most complex group of algae on rocky shores encompassing
organisms which are phylogenetically distinct but morphologically similar and adapted to the same type
of habitat. The morphological parallelism displayed by macroalgae of different phyla appears to be an
adaptation to life in similar conditions (Norton et al. 1981).
Macroalgae contribute to primary production and oxygen release, as well as to the formation
of siliceous and calcareous deposits. Some are small, forming productive turfs on coral reefs, while
others, such as kelps can form large marine forests. Benthic Cyanobacteria are widespread on temperate
rocky and sandy shores (Whitton and Potts 1982) and in the tropics, can form large macroscopic tufts
(for example, Oscillatoriaceae) and smaller but abundant nitrogen-fixing Nostocaceae that are major
components of the reef flora (Charpy et al. 2012). Most of the macroalgal biomass enters the food chains
in the form of debris (Fenchel and Jörgensen 1977), and is consumed by scavengers (bacteria and fungi),
which are considered structuring bodies in coastal communities (especially at the subtidal level). Other
rocky shore organisms feed on macroalgal debris in suspension.
Seaweeds can also have a major role in carbon sequestration (Krause-Jensen and Duarte 2016). The
fate of seaweed net primary productivity and export to the deep sea, is still not well known. But some
studies (Krause-Jensen and Duarte 2016 and references therein) help to provide a first estimate of the
contribution of seaweeds to carbon sequestration and export to the deep sea (> 1,000 m depth), where
the carbon is precluded from exchanging with the atmosphere over long periods of time even after being
remineralized.
Seaweeds offer a habitat for many different species of animals and their morphology influences the
composition of the macrofauna community (Veiga et al. 2014; Matias et al. 2015; Torres et al. 2015).
Most benthic algae display seasonal differences in growth in response to environmental changes
in factors such as radiation, photoperiod, temperature, nutrient availability, and herbivory (Little and
Kitching 1996).Temperature is an important factor in the distribution of algae so that, for the same type
of substrate, rocky shorelines located at different latitudes exhibit distinct communities. Usually, with
increased latitude there is an increase in the abundance of brown algae and a reduction in the red algae
(Lüning 1990). The tropical flora is devoid of large fronds and dominated by calcareous forms, including
crusts, which are more resistant to the high herbivory typical of the tropics (Lubchenco and Gaines 1981).
In tropical waters the predominant leafy forms are Dictyotales and Siphonales, while in northern Europe
dominate the large Fucales and Laminariales.
Benthic communities in temperate and cold waters
The European temperate and cold water intertidal algal communities are dominated by brown algae,
notably Ascophyllum nodosum, Fucus, and Laminaria. Less abundant taxa are Porphyra and Ulva
at higher levels, and Mastocarpus stellatus, Palmaria palmata, and Chondrus crispus lower in the
shore. Other species usually present under the Laminariales canopies include crustose coralline algae,
Polysiphonia spp., Dilsea carnosa, Ulvaria urceolata, Ahnfeltia plicata, and Rhodomela confervoides
(Dawes 1998).
The typical intertidal zonation at these latitudes is characterized by the presence of three distinct
zones. The upper zone (high shore) is dominated by lichens (e.g., Verrucaria maura), littorinids (e.g.,
Littorina), cyanophytes (e.g., Calothrix crustacea), some Chlorophyta (e.g., Prasiola), and some red
(poor in nutrients), the coccolithophores predominate. Dinoflagellates are abundant in both situations.
The cyanobacteria are most commonly found in tropical and/or subtropical environments (Round 1981).
Benthic algae
The benthic algae comprise micro- and macroalgae and both groups are more abundant on rocky shores.
In general, the multicellular benthic macroalgae are commonly called seaweeds because of their size,
construction, and attachment to firm substrata (Dawes 1988). Because they require a stable substrate for
attachment and light, they are confined to marginal areas of continents and islands, where they occupy a
relatively narrow range and some seamounts with tops near the surface (Ramos et al. 2016).
The macroalgae comprise the largest and most complex group of algae on rocky shores encompassing
organisms which are phylogenetically distinct but morphologically similar and adapted to the same type
of habitat. The morphological parallelism displayed by macroalgae of different phyla appears to be an
adaptation to life in similar conditions (Norton et al. 1981).
Macroalgae contribute to primary production and oxygen release, as well as to the formation
of siliceous and calcareous deposits. Some are small, forming productive turfs on coral reefs, while
others, such as kelps can form large marine forests. Benthic Cyanobacteria are widespread on temperate
rocky and sandy shores (Whitton and Potts 1982) and in the tropics, can form large macroscopic tufts
(for example, Oscillatoriaceae) and smaller but abundant nitrogen-fixing Nostocaceae that are major
components of the reef flora (Charpy et al. 2012). Most of the macroalgal biomass enters the food chains
in the form of debris (Fenchel and Jörgensen 1977), and is consumed by scavengers (bacteria and fungi),
which are considered structuring bodies in coastal communities (especially at the subtidal level). Other
rocky shore organisms feed on macroalgal debris in suspension.
Seaweeds can also have a major role in carbon sequestration (Krause-Jensen and Duarte 2016). The
fate of seaweed net primary productivity and export to the deep sea, is still not well known. But some
studies (Krause-Jensen and Duarte 2016 and references therein) help to provide a first estimate of the
contribution of seaweeds to carbon sequestration and export to the deep sea (> 1,000 m depth), where
the carbon is precluded from exchanging with the atmosphere over long periods of time even after being
remineralized.
Seaweeds offer a habitat for many different species of animals and their morphology influences the
composition of the macrofauna community (Veiga et al. 2014; Matias et al. 2015; Torres et al. 2015).
Most benthic algae display seasonal differences in growth in response to environmental changes
in factors such as radiation, photoperiod, temperature, nutrient availability, and herbivory (Little and
Kitching 1996).Temperature is an important factor in the distribution of algae so that, for the same type
of substrate, rocky shorelines located at different latitudes exhibit distinct communities. Usually, with
increased latitude there is an increase in the abundance of brown algae and a reduction in the red algae
(Lüning 1990). The tropical flora is devoid of large fronds and dominated by calcareous forms, including
crusts, which are more resistant to the high herbivory typical of the tropics (Lubchenco and Gaines 1981).
In tropical waters the predominant leafy forms are Dictyotales and Siphonales, while in northern Europe
dominate the large Fucales and Laminariales.
Benthic communities in temperate and cold waters
The European temperate and cold water intertidal algal communities are dominated by brown algae,
notably Ascophyllum nodosum, Fucus, and Laminaria. Less abundant taxa are Porphyra and Ulva
at higher levels, and Mastocarpus stellatus, Palmaria palmata, and Chondrus crispus lower in the
shore. Other species usually present under the Laminariales canopies include crustose coralline algae,
Polysiphonia spp., Dilsea carnosa, Ulvaria urceolata, Ahnfeltia plicata, and Rhodomela confervoides
(Dawes 1998).
The typical intertidal zonation at these latitudes is characterized by the presence of three distinct
zones. The upper zone (high shore) is dominated by lichens (e.g., Verrucaria maura), littorinids (e.g.,
Littorina), cyanophytes (e.g., Calothrix crustacea), some Chlorophyta (e.g., Prasiola), and some red