Survey & documentation of Mangroves in Coastal

CHAPTER-4 MANGROVE DISTRIBUTION IN KARNATAKA

Karnataka has a coastline of over 320 kilometers. Fourteen rivers and several small rivulets, which originate in the Western Ghats cut across the coast to join the Arabian Sea. Towards the coast, the salt water tides from the sea travel several kilometers interior through the river mouths providing congenial habitats for mangroves. Most mangroves are of the fringing type in linear formations along the river or estuarine banks. Where the estuaries are wider, especially in Swarna-Sita-Kodi, Gangoli, (towards the mouth of Haladi-Chakra-Kollur rivers), Aghanashini and Kali there are several remarkable locations for mangroves.

4.1 Method of study Several locations have been visited covering all the important estuaries and the vegetation studied. Due to the fringing nature of mangroves it is difficult make any quantitative estimates of the mangroves. However the data about species collected locality-wise, has been submitted to ISRO, to integrate with remote sensing data, so as to facilitate a comprehensive information system on Karnataka’s mangrove diversity. The latitude and longitude of all the study locations have been collected using the Geographical Positioning System (GPS). Along with mangroves have been also studied the distribution of mangrove associates. This study, being of limited nature, was carried out as a one time study. There are obviously more number of locations to be studied yet, especially for some of the seasonal plants. But the current study is a good record for most of the perennial plants, both mangroves and non-mangroves.

The names of rivers/estuaries and the respective locations studied in each for mangroves and their associations are given in Table-4.1. (See also Maps 4.1, 4.2 and 4.3).

4.2 Salient Features of Mangrove Distribution Coastal Karnataka is one of the better-developed geographical areas of the State with high degree of economic development and density of population. The settlements in the coastal region consists 22 urban agglomerations and 1044 villages. The region supports high degree of agricultural and horticultural activities, fishing and aquaculture, sand and shell mining, industry, harbour development, trade and transport etc. which naturally have their toll on coastal ecosystems, including mangroves. The Project Seabird Naval Base has converted 32 sq.km of land, including some of the mangrove areas, into a highly man-modified complex of artifacts.

According to the State of the Environment Report and Action Plan, 2003 (Department of Forest, Ecology and Environment, Government of Karnataka) “Many coastal depressions in the vicinity of mangrove habitats are filled with mud scooped from lagoons to cultivate coconut plantations. The coir retting carried out mainly in mangrove cleared areas, is a microbial process and causes pollution of water, air and soil, which in turn, affects the marine resources, quality of estuarine banks and nearby beaches.”

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Table 4.1. Distribution of mangrove study sites in the rivers/estuaries of coastal Karnataka

District River/estuary Names of locations studied No Dakshina Netravati-Gurpur Gattikudur, Bajala, Kenjur 03 - Mulki-Pavanje Pavanje, Chelaru, Koruvayalu, 10 Shashihitalu, Vaigegudde, Chitrapu, Korvayalu, Mulki, Kokrane, Hejmadi, Udiyavara Pangala, Mattu, Jarukuduru, 06 Katapadi, Udiyavara, Yenagudde Swarna-Sita-Kodi Kukkade, Bokkapatna, Haradi, 07 Hangarkatta, Airodi, Parampalli, Kotaitattu Haladi-Chakra- Gujjadi, Hangalur, Kodi, Anagalli-1, 16 Kollur Anagalli-2, Navunda, Herikudru, Jaladi, Tallur, Soccalgatta, Uppinkudru, Belthur, Moovathu- mudi, Arate, Bantwadi, Trasi Baindur (Uppunda) Alvekodi 01 Uttara Venktapur Heble, Mogerkeri, Shirali, Kantada- 04 Kannada hitlu Island-1, Kasarkod, Kalshanmotte, 08 Hosapattan, Mulkod, Devanmotte, Mavinkurve, Kulkod Badgani creek Pavinkurva, Haldipur 02 Alvekodi creek Honmavu, Sasihitlu, Devgundi 03 Aghanashini Gudikoppa, Tudibele, Masurkurve, 14 Jeshtapura, Kekkinkodi, Keppe- kurve, Bargi-gazni, Kimmanikodi, Paduvani, Aigalkurve, Mudangi, Morba, Mankon, Karkimakki Gangavali Gangavali, Bilihonge, Agragone, 07 Ulvare, Mudnur, Sagadgeri, Mogta Kali Kadwad-1, Kadwad-2, Hotegali, 14 Hangon, Sadhashivgad, Kanasgeri, Asnoti, Devbagh, Halebagh, Halga, Makkeri, Ambejug, Jugar, Siddar Total localities surveyed in coastal Karnataka 98

There is high degree of general adverse impacts on mangrove vegetation all along the coastal tract. Nevertheless, in the recent years, there are also organized efforts to restore mangroves in suitable areas. Table 4-2 provides details regarding the presence of various true mangrove species in the estuaries of the State.

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Table 4-2: Estuary-river-wise distribution of true mangroves (eumangroves)

Sl. Mangrove species Name of estuary/river No. 1 2 3 4 5 6 7 8 9 10 11 12 13 1 Acanthus ilicifolius P P P P P P P P P P P P P 2 Lumnitzera racemosa - - - - P ------P 3 Excoecaria agallocha P P P P P P P P P P P P P 4 Aegiceras corniculatum P P P P - - - P - P P P 5 Porteresia coarctata P P P - P - - - - - P P P 6 Bruguiera cylindrica - - - - - P ------7 Bruguiera gymnorrhiza - P P P P - P - - - - - P 8 Kandelia candel P P P P P - P P P P P P P 9 Rhizophora apiculata ------P P P 10 Rhizophora mucronata P P P P P P P P P P P P P 11 Sonneratia alba - P P P P P P P P P P P P 12 Sonneratia caseolaris P P P P - P P P - P P P 13 Avicennia marina - P P P P - P - - P P P P 14 Avicennia officinalis P P P P P - P P P P P P P 15 Acrostichum aureum (fern) P P P P P - P P - - P P P Note: P-Present Name of estuary/river: 1. Netravti-Gurpur; 2. Mulki-Pavanje; 3. Udiyavara; 4. Swarna- Sita-Kodi; 5. Haladi-Chakra-Kollur; 6. Baindur; 7. Venktapur; 8. Sharavati; 9. Badagani creek; 10. Alvekodi creek; 11. Aghanashini; 12. Gangavali; 13. Kali

The above Table shows that the combretaceae tree Lumnitzera racemosa is present only in Halad-Chakra-Kollu estuary and Kali estuary. Bruguiera cylindrica was observed only in Baindur estuary. Rhizophora apiculata was found only in the estuaries of . Whereas Brugiuiera gymnorrhiza is somewhat common in the estuaries of Udupi and , in Uttara Kannada it is restricted to only the Kali estuary, but for a lone tree in the Venktapur backwaters of .

4.2.1 Estuarine complex of Netravati-Gurpur rivers This is one of the highly stressed estuarine complex of Karnataka State. It has a spread of about 1920 ha; but the mangrove vegetation is not all that good. Table 4.2 shows that only 8 of the 15 true mangrove species were observed in this estuary. Species such as Rhizophora apiculata, Bruguiera spp., Lumnitzera racemosa, and Avicennia marina could not be observed. There is however good diversity of mangrove associates, which include Cerbera manghas, Cyperus malaccensis, Derris trifoliata and Caesalpinia crista.

4.2.2 Estuarine complex of Mulki-Pavanje rivers This complex sustains more of mangroves than the previous, despite its smaller size. However, due to human exploitation mangroves are on the decline. Twelve of the 15 mangrove species of Karnataka are found here. Pavanje village itself and Chitrapu have 11 species each. Of the mangrove associates the rare tree Morinda citrifolia and Thespesia populnea, rare for the Karnataka coast occur at Haleyangidi. Cerbera manghas is sparingly present.

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4.2.3 Udyavara estuary The estuary has 11 species of true mangroves. Katapadi and Jarukudru are rich in mangroves; there is nothing notable about the mangrove associates.

4.2.4 Estuarine complex of Swarna-Sita-Kodi rivers There is considerable disturbance of the mangroves of this estuarine complex. Here also 11 species of mangroves are found. Hangarakatta is a promising locality. Of the mangrove associates are Cyperus malaccensis, Cerbera manghas, Derris trifoliata, and Caesalpinia crista.

4.2.5 Estuarine complex of Haladi-Chakra-Kollur rivers The combined estuary of these three rivers is spread over an area of 2550 ha in the . There are several notable patches of mangroves here dominated by Rhizophora mucronata, most of which is raised by the Forest Department. Shrimp culturing in the fields adjoining estuarine complex is quite widespread. There are at least 13 species of mangroves out of the 15 found in Karnataka this complex. Bruguiera cylindrica and Rhizophora apiculata could not be traced, although the latter was reported to be occurring according to Rao and Suresh (2001). Lumnitzera racemosa was found only at Hangallur. Rao and Suresh (2001) reported the same also from Vadera Hobli and Gujjadi. Some shrimp farmers also have raised mangroves around their prawn farm, particularly to protect the bunds, with promising results. Of the mangrove associates may be mentioned Calophyllum inophyllum, Cerbera manghas, Cyperus malaccensis, Derris trifoliat, Dolichandron spathacea, Premna corymbosa etc.

Upstream death of mangroves has been observed following construction of barrages for fresh water storing in the rivers Chakra and Kollur. Most mangroves, including the ones, which can grow in low salinity, such as Kandelia candel, Sonneratia caseolaris have died due to fresh water influx. The mangrove death following barrage construction needs, however, more investigation.

4.2.6 Baindur estuary This is a small estuary and a study was carried out at Alvekodi towards the mouth of the estuary. The estuary is notable for the rare presence of Bruguiera cylindrica, perhaps the only location for the species in the State. The others present include Avicennia officinalis, A. marina, Sonneratia alba and Rhizophora mucronata.

4.2.7 Venktapur estuary May be due to the heavy human impact from the densely populated places like Bhatkal and Shirali as well as due to the smallness of the estuary, there is not much of mangroves here. A lone tree of the species Bruguiera gymnorrhiza and a few seedlings were present at Heble. This is the only tree of the species in the Honavar Forest Division, the territory of which covers 3 more estuaries (Sharavati, Aghanashini, and Gangavali).

4.2.8 Sharavati estuary A fine estuary though, it has only 8 species of mangroves. Species such as Avicennia marina and Rhizophora apiculata are altogether absent. Sonneratia alba and Rhizophora mucronata are sparingly present only towards the river mouth, obviously because of more salinity. The major reason for the absence or rarity of true mangroves could be the constant release of fresh water from the various hydel projects of the river. Added to that is

Environmental Management & Policy Research Institute 32 Survey & documentation of Mangroves in Coastal Karnataka prominent sand bar across the mouth of the river that leaves only a small outlet to the sea. The estuary is most remarkable along the coast for the fairly good growth of the low salinity preferring Sonneratia caseolaris. This tree also grows well around the river islands and contributes to some extent the firewood needs of the locals. The largest population of Cerbera manghas is found alongside this estuary.

4.2.9 Badgani creek This small creek towards the north of Sharavati has small patches of mangroves notable for Aegiceras corniculatum, Avicennia officinalis and Rhizophora mucronata.

4.2.10 lvekodi creek This small creek towards the immediate south of Kumta town has high amount of salinity and is good for Avicennia marina, A. officinalis, Rhizophora mucronata and Sonneratia alba. There are some successful plantations of R. mucronata, raised by the Forest Department, and closely visible from the NH 17.

4.2.11 Aghanashini estuary This is one of the largest estuaries of the State. It has 12 species of mangroves, including Rhizophora apiculata and Avicennia marina. There is a small sacred grove dominated by Avicennia officinalis alongside Masurkurve island. Rampant conversion of estuarine rice fields (gaznis) into shrimp aquaculture has destroyed most of the old mangroves. However, in the recent years, due to special efforts by the Forest Department there is considerable mangrove afforestation, which has been dealt with elsewhere in this report. Notable of the mangrove associates here are Salvadora persica, closer to the river mouth and Crateva magna several kms interior, where there is more fresh water influx.

4.2.12 Gangavali estuary Situated towards the south of the Ankola town this river estuary is home for 12 species of mangroves. Though mangrove habitats are few, all along the edge of the river linear strip is found. Some small good patches occur at Bilihonge and Agragone. The river mouth has good patch dominated by coppicing Sonneratia alba. Good protection and awareness creation among the local inhabitants are necessary for the future of mangroves in this estuary. Notable of the mangrove associates are Hibiscus tiliaceus and Ficus racemosa.

4.2.13 Kali estuary By far some of the best natural mangrove areas of Karnataka are found in this estuary. It has 14 of the mangrove species listed under this survey, the exception being Bruguiera cylindrica. This is the only estuary in Uttara Kannada having Lumnitzera racemosa (at Kanasgeri) and practically the entire population of Bruguiera gymnorrhiza (at Kanasgeri and Sadhashivgad). Notable of the mangrove associates are Barringtonia racemosa, B. acutangula, Hibiscus tiliaceus, Salvadora persica and Thespesia populnea. Fresh water influx from the dams in the interior and good amount of tidal influence have made ideal habitat for mangroves.

References 1. Rao, T.A. and Suresh, P.V. 2001. Coastal Ecosystems of the Karnataka State, . I. Mangroves. Karnataka Association for the Advancement of Science, Bangalore.

2. State of the Environment Report and Action Plan- 2003. Department of Forest, Ecology and Environment, Government of Karnataka, pp. 21-34.

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Map 4.1: Uttara Kannada district map showing Mangroves study areas.

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Map 4.2: map showing Mangroves study areas

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Map 4.3: Dakshina Kannada district map showing Mangroves study areas

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