1. Beneficial and Harmful effects of
weeds under aquatic ecosystem
-J.Delince
BSA-11-409

2. Weeds growing in the aquatic ecosystem
They generally require saturated water condition
They show more adaptations for the survival at that
ecosystem
Aquatic weeds

3. In India the majority of problems due to aquatic
weeds are caused by Eichhornia crassipes
It is also called as water hyacinth or Aakayathamarai
or vengayathamarai
The infestation starts first at Calcutta and spreads as
quick as possible in most of the water bodies of India
Harmful effects of aquatic weeds

4. The Water hyacinth plant has fast way of propagation
and it blocks the stream easily causing flood .
They prevent flow of water so efficiency of irrigation
get reduced and also the irrigation distribution is also
reduced
They cause loss of water through evapotranspiration
which is 3-4times more than the normal
And the water hyacinth when present on excess it
degrades the quality of the water.
Harmful effects of aquatic weeds

5. Excess growth of these weed also prevents the use of
boats and other machineries in the water body.
It also sometimes on decomposition cause increase in
organic content which results in Eutrophication and
algal blooming.
It also in the irrigation bunds and cause water loss
Excessive growth of same aquatic weed species
reduces the diversity of other wildlife(Typha latifolia)

6. Azolla plant host the azolla weevil(Stenopelmus rufinases)
Also in high intensities cause de-oxygenation of water.
Lemna sps is an highly invasive plant cause degradation of
aquatic ecosystem
Marsilea quadrifoliata is a troublesome weed in rice field.
Nelumbo nucifera , Nelumbo cristata Both the plants are
reducing the recreational activities like boating, swimming
in that waterbody
Pistia stratioites affects the fish growth, power generation
,water flow etc.
Spirodela polyrrhiza reduce the quality and quantity of
water and also increases organic loading

7. Many weeds species acts as food for fish or encourage the
growth of the phytoplankton and zooplankton, in turn
encourage fish production.
Also the water hyacinth sometimes acts a good dwelling
place or hiding place of fishes
The weeds which are growing in clean water bodies can be
used as animal feed
Also, water hyacinth is having the capacity to absorb the
heavy metals from the effluents released from the
industries
Some are used in cottage industries for making mats,
curtains, fencing, basket etc.
Beneficial effects

8. Also they have high organic matter ,and so we can
use them in the bio gas production.
Also the substrate from the water hyacinth can be
used in mushroom cultivation.
The water hyacinth is also used in the reclamation of
alkaline soils.
Mercuric products and cadmium, lead , zinc in water
was efficiently absorbed by azolla and so it is used to
remove the heavy metals
Azolla is also used in biogas and biomass production
It is also used in rice fields for having the nitrogen
fixing bacteria

9. And from the flower of the water hyacinth, a dye is
extracted for ink preparation
And after decomposition of aquatic weeds we can get
a good organic manure.
It acts as feed for carps. This system is exploited in
controlling of aquatic weeds.
And sometimes they can also can be grown for
aesthetic value because of their beautiful flowers like
Nyphaea sps and Nelumbo sps.
And the fruit,seed,rhizhomes of nelumbo has high
therapeutic potential

10. And the extracts of Nelumbo cristata is having
hepatoprotective property and prevents damage to
liver.
Lemna sps absorbs toxic metals like arsenic and
uranium and also used in the bio-remediation of
water.
Pistia stratioites can absorb excess nitrogen and
phosphorous in water
The ethanolic extract of pistia stratioites is used
against the nematode Ascardia galli

11. Thankyou