INTERNATIONAL MANGROVE DAY
Mangroves in Mashem, Canacona.
There are about 80 different species of mangrove trees. All of these trees grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate. Mangrove forests only grow in tropical and subtropical latitudes near the equator because they cannot withstand freezing temperatures.
Many mangrove forests can be recognized by their dense tangle of prop roots that make the trees appear to be standing on stilts above the water. This tangle of roots allows the trees to handle the daily rise and fall of tides, which means that most mangroves get flooded at least twice per day. The roots also slow the movement of tidal waters, causing sediments to settle out of the water and build up the muddy bottom.
Mangrove forests stabilize the coastline, reducing erosion from storm surges, currents, waves, and tides. The intricate root system of mangroves also makes these forests attractive to fish and other organisms seeking food and shelter from predators.
Goa houses 16 mangrove species and it has one of the best mangrove forests in the country. Chorao Island in Mandovi river has one of the best mangrove forests and houses most of the species found in Goa.
The following listed are the species-wise description of mangroves found in Goa:
1. Rhizophora mucronata: It is a moderate sized tree, much branched, very rough bark, leaves elliptic, broad, opposite, pale beneath with black dots, flowers yellowish white, four petals, radicle slender, elongated, 15 to 40 cms. long, flowering & fruiting takes place in between December to Mid June. Locally known as Kandal, it is available in plenty in the high salinity areas in all the estuaries.
2. Rhizophora apiculata: It is a moderate sized much branched tree with rough bark, leaves elliptic, lanceolate, dark green above, base tapering, pink petioled, clustered towards end of branches, infloroscence 3-4 times forked, 4-8 flowered, flowers white, radicle thick, short and cylindrical, upto 30 cms. in length. Flowering and fruiting takes place in between December to May. It is seen mainly in between R. mucronata trees, which is dominant species. The species is found occasionally here and there and its total occurrence is quite less in Goa.
3. Bruguiera gymnorrhiza: It is a straight stemmed, buttressed tall tree, upto 30m. in height, dark coloured, fissured bark, leaves elliptic, pointed, pale beneath, crowded at branchlet end, flowers solitary, petals bifid with hairs at the base, calyx red to bright red, radicle 15-20 cms long, faintly ribbed, alike ladyfinger. Flowering and fruiting takes place in between November to April. It is found in low salinity areas and can be seen in the interior areas of the State. The tree has a conical shape and is seen mainly in Zuari & Chapora rivers.
4. Bruguiera cylindrica: It is a medium to tall buttressed tree with smooth grey bark, leaves oblanceolate, thin, elliptic, flowers white to greenish, radicle 10-15 cms, short. Flowering and fruiting takes place in between the months of November to April. The species is observed in most of the river estuaries of the State and smaller size trees only are seen. It does not form a colony and is seen scattered here and there.
5. Ceriops tagal: It is a small, 1 to 2 m tall straight stemmed tree or shrub forming buttress. Stem has lot of lenticels, leaves simple, opposite narrowed downwards, collected at branchlet end, flowers white, small and in cyma inflorescences. The species is localized to Terekhol river only and also planted in Chapora river. Flowering and fruiting takes place in between January to April.
6. Kandelia candel (K. rheedi): It is a small, 5-6 tall tree with smooth reddish bark, leaves dark green, polished above, shortly petioled, elliptic, flowers white, radicle 30-40 cm long and slender. Distributed in all estuaries of Goa. Flowering and fruiting takes place two times in a year, prominently from December to April and also from September to December.
7. Avicennia officinalis: A tree with smooth yellowish grey bark, low branching, leaves very fine, silvery white, tomentose beneath. Flowers yellow, collected in small clusters, capsule velvety, compressed, obvate and pointed. It is found in all estuaries and make colonies. Profuse seedings & regeneration is observed. Flowering and fruiting takes place in between March to August.
8. Avicennia marina: It is known as “White mangrove” due to its white bark, leaves opposite, shortly petioled, glossy green on upper side & dull grey or silvery white tomentose hair on lower side, flowers yellow or white, fruit a compressed capsule. Found in all estuaries and make colonies. Flowering and fruiting takes place in between March to August. Profuse seedings & regeneration is observed.
9. Sonneratia alba: It is much branched moderate size tree, bark orange brown / grey, branches silvery grey, swollen, leaves leathery, opposite, elliptic, thickened, flowers solitary or in threes, white, pale green, fruit about 3 cms dome shaped. It is available in plenty in higher salinity areas. Profuse regeneration forming pure patches is observed. Flowering and fruiting takes place twice in a year, from January to April and September to December.
10. Acrostichum aureum: It is erect fern, attaining height upto 1.5m having small bushy appearance, fibrous typical fern like roots but without any aerial roots. Pinnate leaves with a terminal leaflet.
11. Sonneratia caseolaris: It is a moderate sized tree, brown rough bark, leaves 5-10 cms long, broadly obvate, flowers tinged with rose colour, fruit fleshy, cushion shaped. It is found in low salinity areas, on the higher reaches of the rivers. Flowering and fruiting takes place twice in a year, from January to April and September to December. Fine patches showing excellent growth are seen at many places, particularly along Zuari river, in Khazan land in Borim and Shiroda.
12. Aegiceras corniculatum: It is a small shrubby tree, bark brown with reddish tinge, leaves alternate, elliptic, flowers white, in umbels, fruit cylindrical, curved, very small. Available in plenty in low salinity areas. Flowering and fruiting takes place in between February to April.
13. Excoecaria agallocha: It is a much branched tree, upto 5 m high. Bark greyish, leaves pale green, alternate, elliptic, produce latex which is poisonous & dangerous to eyes. Flowers dioecious, arranged in sessile axillary catkins. Male and female plants found separately with distinct characters. Found in all the estuaries and is a common species in Goa.
14. Acanthus illici folius: It is a shrub, upto 2 m high, aerial root formation is seen. Leaves glabrous, decussate with pair of spines. Flowers light blue to violet. Fruit 2-3 cms. long. It is found in abundance in all the estuaries. Flowering and fruiting takes place in between February to April.
15. Lumnitzera racemosa: A small tree upto 10 m high. Bark grey and fissured. Pneumatophores are thin, knee shaped. Leaves small, fleshy, oval, clustered towards end of branches Flowers white. Fruit hard, ovoid. Flowering and fruiting in between March to September. Localised to Siolim area, along the bunds.
16. Derris heterophylla: A climber, much branched shrub, evergreen, perennial, tap roots deep sunken and without any aerial growth, compound leaves, 3 to 5 leaflets. Flowering in June to December.
The mangrove population of Canacona taluka comprises of 15 species, belonging to 10 genera under 7 families and 85 species of associate mangroves belonging to 30 genera and 18 families were reported.
Different species of mangrove found in different estuaries of Canacona taluka and other associates of mangrove flora are listed below. The estuaries from Canacona taluka have coverage of around 40 hectares, out of which 43 per cent is contributed by Galgibaga estuary.
Estuary wise composition and configuration of mangrove species.
(I) Talpona:
(i) Talpona, Khalwada: Avicennia officinalis & Avicennia alba - 60%; Rhizophora mucronata- 20%; Bruguiera gymnorrhiza, Acanthus illicifolius, Derris heterophylla & Aegiceras corniculatum - 20%.
Note: - Mangroves are in few patches but dense.
(II) Galgibaga:
(i) Mashem, Loliem : Avicennia officinalis & A. alba - 30%; Rhizophora mucronata & Rhizophora apiculata - 60%; and Aegiceras corniculatum - 10%
(ii) Poinguinim & Galgibaga : Avicennia officinalis & Avicennia alba - 50%; Rhizophora mucronata & Rhizophora apiculata - 40%; and Bruguiera gymnorrhiza & Bruguiera cylindrica - 10%.
Note: - Mangroves are dense at the mouth of the river and forms a ground for fish.
Associates of mangroves
The associates, which are the plants found along with the mangroves, are:
1.Derris heterophylla; 2.Clerodendron inermi; 3.Acrostichum aureum; 4.Cyperus spp.; 5.Porteresia coaretata; 6.Ceasalpinia crista; 7.Salvadora persica; 8.Halophila beccarii; 9.Lannea grandis; 10.Abrus precatorius and 11. Thespesia populnea
Uses of mangroves
Prevention from soil erosion and stabilization of coasts and beaches; Protection of land from tidal surges and cyclonic storms; Aqua culture; Provides fuel wood, green manure, charcoal, timber, etc; Used for boat / canoe making; Provides tannin; Used for thatching material, cordage and rope material; Used for art and craft, bow making; Used as food and beverage; Widely used for medicinal purposes; Useful for bee hives and provides wax and honey; Useful for recreational purpose as eco-tourism; Provides an excellent home to birds and animals.
When canacona taluka had to face the floods in the year 2009, the people living in the coastal areas of Mashem and Galjibaga could in real sense feel the importance of mangroves in their locality.
It is observed that because there is no much awareness about mangroves, people exploit these plants. Many local depend on them for getting a good catch of fish, some cut them for firewood and remaining lot are just ignorant about their existence.
On this International Mangrove day, we call the attention of local bodies of the area to make people aware about the importance of this savior of ours and take some initiative in conserving the mangroves.
(The writer is a teacher Grade I, Satyawati Soiru Angle Higher Secondary School and Member of Mangrove Society Of India)
