Environmental Engineering Reference
In-Depth Information
the other. In some seaweeds, two peak growth
periods with a half-yearly growth cycle were
observed, while in other seaweeds, only a sin-
gle peak growth period was observed. In gen-
eral, maximum growth has been observed in
many algae in two seasons of the year, one
from June to August and another from
November to January. The commercially useful
algae should be collected only during their
peak growth periods in order to get more quan-
tity of raw material and better yield of fi nished
products with good quality.
Studies on the fruiting periods and relative
preponderance of vegetative and reproductive
phases of many commercially important
seaweeds indicated that the fruiting behavior
varies in different seaweeds growing along the
Indian coast. Though reproduction was
observed throughout the year, two fruiting
seasons in a year in many algae and one fruit-
ing season in other algae were found.
Information on the spore output from econom-
ically important algae was collected. As enor-
mous number of spores was found to be
produced from an alga, they can be success-
fully raised to germlings in the laboratory or
nursery and then to harvestable size plants in
the sea by transplantation. Periodicity or
rhythm in the liberation of spores was observed
in some seaweeds, while there was no such
periodicity in the shedding of spores in other
seaweeds. The spore output season and also the
period of maximum sporulation varied from
species to species. Information was collected
also on the spore germination, survival of
germlings, and life cycle of some marine algae.
The results of several studies on the growth,
fruiting behavior, and sporulation of the eco-
nomically important marine algae growing in
different area paved the way to utilize the
available marine algal resources in a rational
way for commercial exploitation and cultiva-
tion. Studies on the diversity, physiology,
biochemistry, and utilization of potentially
useful species will be necessary to harness the
full potential of seaweed resources and to do
so sustainably.
4
Utilization of Seaweeds
from Historical Period
to Present Day
The earliest record of use of seaweeds dates back to
2700 BC in the compilation on “Chinese Herbs” by
Emperor Shen Nung. Seaweeds have been a part of
the Japanese diet since 300 BC. Seaweeds are
mainly eaten in the oriental countries like Japan,
China, Korea, and more recently in the USA,
Europe, Philippines, Indonesia, Chile, Taiwan,
Vietnam, Russia, Italy, and India. The Republic of
Korea has the highest per capita consumption of sea-
weeds in the world. After human food consumption,
the next most valuable commercial use of seaweeds
is as a raw material for extraction of phycocolloids
like agar, alginate, and carrageenan which are used
in several industries. The current phycocolloids (sea-
weed gels) industry stands at over US $ 6.2 billion.
The world production of commercial seaweeds has
grown by 119 species since 1984, and presently, 221
species of seaweeds are utilized commercially
including 145 species for food and 110 species for
phycocolloid production. These have been used as
food for human beings, feed for animals or manure
for plants, and source of various chemicals. In the
recent past, seaweeds have also been gaining new
systems for biologist seaweed liquid fertilizer.
Seaweed products are used in our daily lives in
one way or another (e.g., seaweed polysaccharides
are employed in the manufacture of toothpastes,
soaps, shampoos, and cosmetic products such as
creams and lotions and also as a source for animal
nutrition). In addition, it is used in wastewater treat-
ment, paper industry, and medical research (Cruz-
Suarez et al.
2010
). Recently, seaweed fi gure
prominently debates about the energy and biofuel
production. They have been discussed as a potential
source against global warming where seaweeds
and algae are very effi cient carbon sinks which
means that they absorb more carbon than their rate
emission. Marine algae may also be used as energy
collectors, and potentially useful substances may
be extracted by fermentation and pyrolysis. The
various benefi ts of different algal species available
worldwide are presented in Table
1
.
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