Environmental Engineering Reference
In-Depth Information
the seawater, they photosynthesize and produce
food. Seaweeds are found in the coastal region
between high tide and low tide and in the subtidal
region up to a depth where 0.01 % photosyn-
thetic light is available. Plant pigments, light,
exposure, depth, temperature, tides, and the
shore characteristics combine to create different
environments that determine the distribution
and variety among seaweeds (Dhargalkar and
Kavlekar
2004
). Seaweeds or marine macroal-
gae are primitive nonfl owering plants, without
true root, stem, and leaves. They form one of the
commercially important marine living renew-
able resources. Seaweeds occur in the intertidal
shallow and deep waters of the sea and also in
estuaries and backwaters. They grow on rocks,
dead corals, stones, pebbles, solid substrata, and
other plants. They require certain environmental
conditions for proper growth and establishment
in different regions of the coastline. However,
the topography, physical nature of the substra-
tum, salinity, currents, tidal action, and other
factors of the marine environment vary in differ-
ent parts of the coastline, and as a result of these
fl uctuations, marked changes occur in the distri-
bution and abundance of different kinds of
seaweeds.
2
Classifi cation of Seaweeds
Based on the type of pigments, external and
internal structure, and reproduction, seaweeds
are divided in to four broad groups: green, blue-
green, brown, and red. Botanist refers to these
broad groups as Phaeophyceae, Rhodophyceae,
Cyanophyceae, and Chlorophyceae, respec-
tively. Brown seaweeds are usually large and
range from the giant kelp; red seaweeds are usu-
ally smaller, generally ranging a few centime-
ters to about a meter in length and they are not
always red. They exhibited sometimes purple
and even brownish red. Green seaweeds are also
small with a similar size range to the red
seaweeds.
3
Ecology and Biology
of Seaweeds
Seaweeds are ecologically important primary
producers, competitors, and ecosystem engi-
neers that play a central role in coastal habitats
ranging from kelp forests to coral reefs.
Although seaweeds are known to be vulnerable
to physical and chemical changes in the marine
environment, the impacts of ongoing and future
anthropogenic climate change in seaweed-
dominated ecosystems remain poorly under-
stood (Harley et al.
2012
). Ecological studies
have been carried out on the marine algal veg-
etation of different localities of Indian coast
by various workers. They provided data on the
seasonal changes and zonation of algae and on
the environmental conditions existing in those
areas. The changes in the total emergence and
submergence, topography of the coast, surf
action, and levels at which the plants grow
were found to contribute much to the varia-
tion in the growth of the algae. Every year
fresh plants develop from the reproductive
bodies liberated by the plants of the previous
generation or from the perennial basal portion
of the old plants. The period of regeneration
and increase and decline in growth vary from
species to species and also from one locality to
1.1
Seaweed Wealth in India
India has a vast coastline more than 9,000 km long,
a number of estuaries, backwaters, and island, rocky,
or coral formations occurring in Tamil Nadu and
Gujarat states and in the vicinity of Bombay, Karwar,
Ratnagiri, Goa, Vizhinjam, Varkala, Visakhapatnam,
and few other places like Chilka and Pulicat lakes.
India is rich in algal biodiversity country and has
large stretches of suitable area for growth. According
to Oza and Zaidi (
2001
), totally 844 species of
marine algae available in India belong to different
genera and classes as shown below:
Genera
Species
Chlorophyceae
43
216
Phaeophyceae
38
194
Rhodophyceae
136
434
217
844
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