466
N. A. H. El Semary
1 Introduction
1.1 Importance of Algae
Algae are photosynthetic plant-like organisms that have chlorophyll a in common as
well as having no embryo, no vascular tissues, no roots, stems or leaves. Their size
varies from unicellular microscopic forms to multi-cellular macroscopic organisms
[1]. Their diverse cellular organization, sizes and structure indicate that they are not
closely-related phylogenetic group but in fact a diverse group. They occupy almost
all habitats even the most extreme. Marine/brackish water algae are being the focus
of this chapter as they represent the base of food chain for edible aquatic animals
such as fish and crustaceans. Based on their sizes, marine algae can be classified
into macroscopic and microscopic forms. The macroscopic forms are usually called
seaweeds. They are found in supra-littoral, littoral and sub-littoral zones of marine
environments and are mostly benthic. In their comprehensive review, [2] enumerated
the advantage of seaweeds where most of the marine seaweeds are green algae, brown
algae and red algae. The latter represents an important protein-rich dietary component
for animals and humans. However, algae represent a characteristic direct human food,
especially nori (Porphyra spp.), wakame (Undaria pinnatifida), and kombu (Laminaria japonica). Securing marine food sources would primarily depend on securing
dietary supply that is mainly based on algae. According to [2], seaweeds represent
primary producers of oxygen and organic matter through photosynthesis and represent food for heterotrophs. They also act in nutrient recycling and waste treatment
and can be used as biomonitors of eutrophication as well as indicators of natural
and/or artificial changes in biodiversity. They are of huge economic importance in
different aspects such as food, industry, agriculture and aquaculture [2]. The continuous production of those algae year round is necessitated by their essence as a feed
for aquaculture. Most important algae that are cultivated are (Laminaria, Undaria,
and the red algae Porphyra and Eucheuma/Kappaphycus. These red seaweeds are
widely cultivated as a source of carrageenan, which is used in the manufacture of
food, both for humans and other animals [2].
With regard to algal nutritional value and according to FOA report, the protein
content of some filamentous cyanobacteria or bluegreen algae ranged between 60–
74% and for filamentous green algae (16–32%). The protein contents of green and
red seaweeds ranged between 6–26% and 3–29%, respectively. The lipid levels for
filamentous green algae ranged between 2–7%. The lipid contents of both green
(0.3–3.2%) and red seaweeds (0.1–1.8%) were less than those values in case of
filamentous algae. The ash content of filamentous blue-green algae ranged from 3–
11%. The ash contents of green seaweeds ranged from 12–31%. Red seaweeds had
an extremely wide range of ash contents (4–47%) (http://www.fao.org/docrep/012/
i1141e/i1141e01.pdf).
The chapter here focuses on the benefits that algae offer aquatic animals whether
as a feed or as a colourant and methods of cultivating algae to allow continuous
year-round biomass supply. The chapter also discusses ways of maximizing algal
N. A. H. El Semary
1 Introduction
1.1 Importance of Algae
Algae are photosynthetic plant-like organisms that have chlorophyll a in common as
well as having no embryo, no vascular tissues, no roots, stems or leaves. Their size
varies from unicellular microscopic forms to multi-cellular macroscopic organisms
[1]. Their diverse cellular organization, sizes and structure indicate that they are not
closely-related phylogenetic group but in fact a diverse group. They occupy almost
all habitats even the most extreme. Marine/brackish water algae are being the focus
of this chapter as they represent the base of food chain for edible aquatic animals
such as fish and crustaceans. Based on their sizes, marine algae can be classified
into macroscopic and microscopic forms. The macroscopic forms are usually called
seaweeds. They are found in supra-littoral, littoral and sub-littoral zones of marine
environments and are mostly benthic. In their comprehensive review, [2] enumerated
the advantage of seaweeds where most of the marine seaweeds are green algae, brown
algae and red algae. The latter represents an important protein-rich dietary component
for animals and humans. However, algae represent a characteristic direct human food,
especially nori (Porphyra spp.), wakame (Undaria pinnatifida), and kombu (Laminaria japonica). Securing marine food sources would primarily depend on securing
dietary supply that is mainly based on algae. According to [2], seaweeds represent
primary producers of oxygen and organic matter through photosynthesis and represent food for heterotrophs. They also act in nutrient recycling and waste treatment
and can be used as biomonitors of eutrophication as well as indicators of natural
and/or artificial changes in biodiversity. They are of huge economic importance in
different aspects such as food, industry, agriculture and aquaculture [2]. The continuous production of those algae year round is necessitated by their essence as a feed
for aquaculture. Most important algae that are cultivated are (Laminaria, Undaria,
and the red algae Porphyra and Eucheuma/Kappaphycus. These red seaweeds are
widely cultivated as a source of carrageenan, which is used in the manufacture of
food, both for humans and other animals [2].
With regard to algal nutritional value and according to FOA report, the protein
content of some filamentous cyanobacteria or bluegreen algae ranged between 60–
74% and for filamentous green algae (16–32%). The protein contents of green and
red seaweeds ranged between 6–26% and 3–29%, respectively. The lipid levels for
filamentous green algae ranged between 2–7%. The lipid contents of both green
(0.3–3.2%) and red seaweeds (0.1–1.8%) were less than those values in case of
filamentous algae. The ash content of filamentous blue-green algae ranged from 3–
11%. The ash contents of green seaweeds ranged from 12–31%. Red seaweeds had
an extremely wide range of ash contents (4–47%) (http://www.fao.org/docrep/012/
i1141e/i1141e01.pdf).
The chapter here focuses on the benefits that algae offer aquatic animals whether
as a feed or as a colourant and methods of cultivating algae to allow continuous
year-round biomass supply. The chapter also discusses ways of maximizing algal