Content :

1.Introduction

2.Meaning of Spawning

3.Fish Spawning

4.Biology of Spawning

5.Types of Spawning

6.Induced breeding for Spawning

7.Role of Environmental factors

8.Summary

9.Conclusion

10.Reference

What is mangrove??The word "mangrove" is obscurely

connected with the Portuguese

word "mangue" and the English

word "grove“.

Mangroves are plants living in the

tropical and subtropical tidal

coastal areas specifically at the

intertidal zone that lies between

sea and land.

This includes the swampy and saline

(brackish water) intertidal zone of

deltas, lagoons, marine shorelines

and estuaries.

CONT…

Mangroves are necessarily tolerant of high salt levels and have mechanisms to take up water

They draw up saltwater by maintaining a lower hydrostatic pressure in their above-water cells (osmosis).

Mangroves exclude a great deal of salt at or near their roots, but still have a salinity level approximately 10 times higher than most other plants.

Mangrove Distribution

Mangroves are commonly found

throughout the world between latitudes 32°N and 38°S. ]

Mangroves are found practically in almost all the continents, excepting Europe, the Arctic and Antarctic.

Best mangroves are found in Asia, especially in India and Bangladesh - the Sunderbans are the largest mangrove forest in the world both in size as well as biodiversity.

The total area of mangroves in India is about 6,740 sq. km, which is about 7% of the world's total area of mangroves

Of the total mangroves 80% are present along the east coast, mostly forming the Sunderbans, Bhitarkanika and the Andaman & Nicobar mangrove

The remaining 20% mangroves are scattered on the west coast from Kutch to Kerala.

The major plant species forming the mangrove ecosystemhave aerial roots

1. prop roots2. cable roots3. stilt roots

Rhizophora spp (Red mangroves) have prop roots It descends from the trunk and branches It provides a stable support system

Other mangrove species, including the white mangroves obtain stability with an extensive system of shallow, underground “cable roots”

It radiate out from the central trunk for a considerable distance in all

directions. pneumatophores extend from these cable roots.

○ EXAMPLES:- A. marina

Stilt roots are the main organs for breathing especially during the high tide.

Stilt roots also serve to anchor the plants.

They are important in aeration, because the mangrove mud tends to be anaerobic

EXAMPLES:-Avicennia marina

Avicennia offficinalis

Rhizophora mucronata

Its stilt roots extend more than a meter above the soil surface and contain many small pores (lenticels) which at low tide allow oxygen to diffuse into the plant and down to the underground roots by means of open passages called aerenchyma.

The lenticels are highly hydrophobic and prevent water penetration into the aerenchyma system during the high tide.

Aeration occurs also through lenticels in the bark of mangrove species.

:

These are the special vertical roots, called pneumatophores

It forms from lateral roots in the mud often projects above soil

to a height of 20-30 cms It permits some oxygen to reach the

oxygen-starved submerged roots. The density, size and number of

pneumatophores vary per tree. They are green and contain

chlorophyll.

EXAMPLES:- Avicennia, Sonneratia

MANGROVE FLORA

Rhizophora mucronata Fruit & Folwer of Sonneratia alba Avicennia marina

Fruits of Derris trifolate Fruits of Avicennia marina Flowers & fruits of

Avicennia marina

•This zone is towards

water front

•subject to regular tidal

effect

•They are having stilt

roots, prop roots for

stability and anchorage

Rhizophora apiculata

R. mucronata

2. it develop a strong hold

fast in the form of knee

roots or bent roots as a

supporting organ

Lumnitzera racemosa

•It occurs towards island

area mangroves

•The duration of tidal

submersion is low in this

zone compared to front

mangroves.

Heritiera littoralis

Xylocarnus spp

TYPES OF MANGROVESNAME DESCRIPTION ROOT SEED

•Individual trees may

grow up to 20-25

meters in height.

•The Black Mangrove

is tolerant of high

saline conditions.

•Roots look like tubular

bristles. These bristles

are known as

pneumatophores.

•Roots stick out

vertically and trap

oxygen for its oxygen-

starved root systems.

•The seeds are

viviparous in nature

•Black mangroves

produce seeds in

abundance which

occur throughout the

year.

•It reaches 5.6 meters

and a diameter of 30

centimeters

•This species normally

grows in the back

portion of mangrove

swamps.

•The roots are fibrous,

and this species

coppices reasonably

well.

•They have un-

buttressed roots.

•Germination is

epigeous.

•This is an evergreen

tree

•It grows to about 25

meters in height and

40 centimeters in

diameter at breast

height.

•elaborate prop and

aerial root system

•The roots contain a

waxy substance that

helps keep salt out.

•The seed-like parts -

the propagates - are

large pre-germinated

'seedlings' known

locally as 'monkey

whistles'.

Sundarbans, the largest mangrove on the planet earth

The Sundarban, covers about one million ha in the delta of the rivers:

1. Ganga,

2. Brahmaputra

3. Meghna

It is shared between Bangladesh (~60%) and India (~40%).

It is famous for its marine and estuarine fish resources

Sundarban boast around:-

1. 172 species of fishes

2. 20 species of prawn

3. 44 species of crabs

The Sundarban has been extensively exploited for timber, fish, prawns

and fodder

SUNDARBAN FLORA

ECOLOGICAL IMPORTANCES OF MANGROVE

IMPORTANCES OF MANGROVE IN FISHERY

Major Threats

Hurricanes

2. Root clogging from increased water turbidity

3. Damage from boring organisms and parasites.

1. Deforestation:

Since mangroves are either slow to recuperate from cutting or do not re-sprout after being cut (e.g. the red mangrove), they will never return unless replanted.

2.Diversion of freshwater for irrigation

3.Land reclamation has destroyed extensive mangrove forests.

4.In the past several decades, numerous tracts of mangrove have been converted for aquaculture, fundamentally altering the nature of the habitat

THREAT OF MANGROVES IN INDIA

Mangrove forest destruction and depletion of its natural resources pose one of the most serious social problems in India.

The problem is particularly observed in the western coast where the extent of the remaining mangrove forests is only about 40,000 ha (total area of Indian mangroves is about 350,000 ha).

Conservation measures and afforestationare therefore essential.

Steps taken towards Mangrove Conservation

The Government of India had set up the

National Mangrove Committee at the Ministry of Environment and Forests in 1976 to advise the government about mangrove conservation and development.

Mangrove afforestation project in Goa & Maharashtra:-

Activities sponsored by the UNDP/UNESCO Regional mangrove Project have greatly contributed to mangrove awareness in India.

Three government agencies, assisted the mission

1. the NIO at Goa

2. Forest Department of Goa

3. Social Forestry Circle of Maharashtra State.

CONCLUSION

REFERENCES:

1.WWW.GOOGLE.COM

2.

3.WWW.WIKIPEDIA.COM