Seagrasses Halophila, Syringodium, Thalassia and Thalassodendron) are distributed
Seagrasses are the
marine flowering plants. They are the
only angiosperms that well-being especially grow in tidal and subtidal marine
environment. Seagrasses belongs to families, Hydrocharitaceae and Potamogetonaceae and
they are in
no way related
to the terrestrial
grasses of Poaceae. There are 13 genera and 58 species available all
over the world, from this six genera (Amphibolis, Heterozostera,
Phyllospadix, Posidonia, Pseudalthenia
and Zostera) are mostly restricted to temperate
seas and the
remaining seven genera
(Cymodocea, Enhalus, Halodule,
Halophila, Syringodium, Thalassia and Thalassodendron) are distributed
in tropical seas.
Seagrasses are submerged flowering plants found in
shallow marine waters, such as bays and lagoons and along the continental shelf
in the Gulf of Mexico. A vital part of the marine ecosystem due to their
productivity level, seagrasses provide food, habitat, and nursery areas for
numerous vertebrate and invertebrate species. The vast biodiversity and
sensitivity to changes in water quality inherent in seagrass communities makes
seagrasses an important species to help determine the overall health of coastal
ecosystems.
Seagrasses perform numerous functions:
Stabilizing
the sea bottom
Providing
food and habitat for other marine organisms
Maintaining
water quality
Supporting
local economies
Importance
of Seagrasses:
Seagrasses are a vital part of the marine ecosystem.
This article describes some of the Seagrasses are a vital part of the marine
ecosystem. This article describes some of the most important reasons:
The true importance
of seagrass meadows
to the coastal
marine ecosystem is not fully
understood and generally underestimated. The
rapidly expanding scientific
knowledge on seagrasses
has led to
a growing awareness
that seagrasses are
valuable coastal resources.
Where seagrasses abound, humans benefit directly and indirectly
from the
presence of this
marine vegetation (Marten
and Carlos, 2000).
Eventhough, they contribute a smaller part to taxonomy, these
plants are important
for structuringa number
of ecosystems, stabilizing
coastlines, providing food and shelter for diverse marine organisms
and act as a nursery ground for many
fishes of commercial importance.
1. Seagrass meadows enhance the biodiversity and
habitat diversity of coastal waters. It has been estimated that over 153
species of microalgae (mostly diatoms),
359 species of macroalgae and 178
species of invertebrates
are found on
the seagrass blades
as epiphytes and epizootie
(Phillips and McRoy, 1980).
2. A Seagrass
meadow also acts as nursery and foraging area for a number
of commercially and
recreationally important fish
and shellfish and
other organisms. There are about 340 animals including green
turtles which directly feed on the seagrasses and their epiphytes. Besides, the
marine mammal Dugong, solely feeds on seagrasses.
3. Seagrasses
improve water quality by acting as roughness elements that deflect currents and
dissipate the kinetic energy of the water and thereby creating a relatively
quiet environment favourable for sediment deposition and retention. With the
help of their well-developed root system, they bind the sediments and stabilize
them.
4.Some of the species form reef like structures close to the water surface
that dissipate the
wave energy before
it reaches the
shoreline.
5. Seagrasses
play an important role in carbon and nutrient cycling in the marine
environment. The large biomass produced
by the seagrasses and their epiphytes act as sink for carbon in the
oceans. Seagrass meadows are also
involved in nitrogen cycling through nitrogen fixation (eg. Posidonia oceanica
meadows account for an annual input of 57×1010 gN in the Mediterranean).
6. Seeds of
Enhalus acoroides are
used as food
by the coastal
populations as the nutritional value of the flour derived from the seeds
is comparable to
that of wheat
and rice in
terms of carbohydrate and protein content and in
energetic value and even it surpasses
these types of flour in calcium, iron and phosphorous content
(Montano et al.,
1999). Coastal people use
rhizomes of Cymodocea sp.
(nicknamed as sea
sugarcane) as food,
for the preparation of salad.
7. Seagrasses
are used as filling material for mattresses and shock absorbing materials for the transport of glasswares.
8. Seagrasses
are also used as raw materials in paper industry and in the production of
fertilizer, fodder and feed. Most of the seagrasses are
used extensively as
soil fertilizer for
coconut and other
plantations.
9. A variety of medicines and chemicals are also
prepared from them. Agar like substance,
zosterin is extracted form Zostera sp. Seagrasses use rhizomes of Cymodocea
sp. (nicknamed as
sea sugarcane) as
food, for the
preparation of salad
