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Diminishing of Mangrove Cover Posing Potential Threats to the Biodiversity of Pulicat Lake, South India

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Kannan Vaithianathan at Chinmaya Vidyalaya PAC Ramaswamy Raja Matriculation Higher Secondary School
Kannan Vaithianathan
  • Chinmaya Vidyalaya PAC Ramaswamy Raja Matriculation Higher Secondary School
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Abstract

Coastal zones are facing intense and sustained anthropogenic pressure from a range of driving forces. Demands on the environment are raising serious concerns from environmentalists, stakeholders, coastal communities and researchers. Pulicat Lake is the second largest lake and a very fragile ecosystem. Pulicat provides nursery and breeding grounds to many species of coastal-marine fauna including birds and also supports commercial fishing. Mangroves flourished in Pulicat until the eighteenth century. After several interventions by humans and nature, the mangrove vegetation started to diminish. At present, there are only few patches of mangrove plants left in the Pulicat therefore serious conservation action and restoration is required to prevent the loss of biodiversity.
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Global Journal of Environmental Research 7 (3): 52-55, 2013
ISSN 1990-925X
© IDOSI Publications, 2013
DOI: 10.5829/idosi.gjer.2013.7.3.8198
Corresponding Author: Vaithianathan Kannan, PG Research Department of Zoology & Wildlife Biology AVC College
(Autonomous) Mannampandal, Mayiladuthurai 609305 Tamil Nadu, India.
52
Diminishing of Mangrove Cover Posing Potential Threats to the
Biodiversity of Pulicat Lake, South India
Vaithianathan Kannan
PG Research Department of Zoology and Wildlife Biology AVC College (Autonomous)
Mannampandal, Mayiladuthurai 609305 Tamil Nadu, India
Abstract: Coastal zones are facing intense and sustained anthropogenic pressure from a range of driving forces.
Demands on the environment are raising serious concerns from environmentalists, stakeholders, coastal
communities and researchers. Pulicat Lake is the second largest lake and a very fragile ecosystem. Pulicat
provides nursery and breeding grounds to many species of coastal-marine fauna including birds and also
supports commercial fishing. Mangroves flourished in Pulicat until the eighteenth century. After several
interventions by humans and nature, the mangrove vegetation started to diminish. At present, there are only
few patches of mangrove plants left in the Pulicat therefore serious conservation action and restoration is
required to prevent the loss of biodiversity.
Key words: Biodiversity Conservation Mangroves Restoration East Coast India
INTRODUCTION hectares (19.8%) is found in the Andaman and Nicobar
Mangroves are the salt-tolerant evergreen littoral east coast andhra Pradesh has 42,900 hectares of the total
forest found in the intertidal zones of sheltered shores, mangrove cover [6].
estuaries, tidal creeks, backwaters, lagoons, marshes and The Pulicat Lake (13°25’-13°55’N, 80°03’-80°19’E) is
mudflats of the tropical and subtropical latitudes [1]. the second largest lake in India with an area of 720 km
Mangrove plants have peculiar adaptations such as a span [7] the entire lake has extensive mudflats subject
strong supporting, interlocking and breathing root system to tidal influence. The heritage values of Pulicat Lake
called pneumatophores; viviparous mode of reproduction, have been recognised right from the sixth century [8].
salt regulation and nutrient retention [2]. They are a Pazhaverkaddu means ‘Jungle of roots’, possibly
unique ecosystem that provides ecosystem services to implying to the mangrove vegetation, as mangrove forests
humans. Globally mangroves have an estimated cover were luxuriant in Pulicat Lake until around the end of the
of 15.2 million hectares and are found in 123 countries eighteenth century [9,10]. The Dutch stayed at Pulicat
worldwide. The most extensive is present in Asia (39%) until the year sixteen ninety (Approx) and their ships were
[3]. Information on Indian mangroves was first able to enter Pulicat Lake, which was then about 3.8 m
documented in 1987 and after one decade a detailed status deep. During this period there was assumed to be large
report on mangroves of India was reported [4]. A number scale destruction of mangroves due to the building of the
of studies revealed about the occurrence of mangroves port. Possibly, because of exploitation of the mangroves
from different parts of the Indian coast [5]. At present, and several human interventions, the depth of the lake
there are about 4,87,100 hectares of Indian mangrove reduced to 2 m by approximately eighteen hundred AD
wetlands remains of which 2,75,800 (56.7%) hectares is [9-11]. The lakes name was originally derived from the
spread along the east coast region and 1,14,700 hectares mangrove vegetation, but now there are only small
(23.5%) in the west coast region the remaining 96,600 patches left in this lake, which demands serious
islands. Of the 56.7% of the mangrove wetlands for the
2
Global J. Environ. Res., 7 (3): 52-55, 2013
53
conservation action. Historical records show that losing some of the precious and key plant and animal
about 6,650 to 7,000 years ago, there were luxurious genomes that are likely will not return in the future
mangroves, chiefly of the family Rhizophoraceae, on [19].
the north-western shores of the Pulicat Lake. By Preserving the environmental diversity of mangroves
approximately 1400 AD the mangrove vegetation seemed is essential to maintaining the monetary values for the
to have shifted eastwards, by approximately 18 km, due people who live near them and who depend on them for
to the massive marine regression. Much later, by about their survival. This vegetation provides a buffer zone and
1450 to 1800 AD. these mangroves extended southwards acts as a barrier against the sea furies, floods etc. thereby,
[12]. Approximately ten species of mangroves was averting soil erosion in the coastal zone and protecting
recorded on the banks of Buckingham Canal in the the human habitation [10]. Apart from providing a degree
southern part of Andhra Pradesh. On the eastern bank of of coastal protection for communities - there is evidence
the Pulicat Lake, of the total mangrove vegetation, the that mangroves helped reduce the impact of the Indian
most dominant species (about 80%) was found to be the Ocean tsunami in 2004 [20].
Excoecaria agallocha [13]. Presently the sparse bushes Ecological restoration of mangrove forests has only
of Avicennia marina (Endangered sp.) are found in the received attention very recently [21]. In consulting the
south near Ennore, Kuruvithittu and in small patches original literature on mangrove restoration [21-32] we can
present at the northern parts of Pulicat Lake near find discussions of the costs of restoration. The costs to
Durgarajapattinam. Some natural regeneration can also be successfully restore both the vegetative cover and the
found along the eastern banks of the Buckingham Canal, ecological functions of a mangrove forest have been
north of the Sullurpet-Sriharikota road, south of the reported to be USD 500,000/ha [33, 34].
Sullurpet-Sriharikota road up to Pulincheri kuppam and Palynostratigraphical evidences from areas along the
Rettela and in the Sriharikota Island [14]. In 2010 the coastal belt represent the mangrove vegetation during
Global Nature Fund declared the Pulicat as the early to late Holocene period. Palaeovegetational records
“threatened lake of the year” [15]. with reference to mangrove forests have great potential in
Mangroves are largely destroyed by human-induced assessing the past climate and sea level fluctuations [10,
activities such as urbanization and agriculture, which 12]. Unlike the west coast, due to low topographic slope
poses significant, threats [16]. In India, Mumbai city is and more frequent storms, the east coast is more
one of the well-known examples of the mangrove vulnerable [17]. To avoid any tragic outcome we need to
destruction due to urbanization. All the seven islands of find inexpensive ways like developing a plantation system
Mumbai were reclaimed and linked to a continuous in the Pulicat Lake and if successful this will bring back
landmass after destroying mangroves in the process. In the mangroves and the glory of its dialect that calls
Pulicat Lake an analysis of mangrove history indicated ‘Pazhaverkaddu’ - the Pulicat. If the mangrove restoration
that mangroves flourished at about 6650 years, is done in adequate way, it has potential for biodiversity
whereas the periods around 3100-2799 AD and 2599-2250 enhancement (increase in fish production, prevention
AD years were found unfavourable for mangroves [5]. from natural disasters and habitat for various faunal
At present, the area is represented by Psamophytes and groups), regeneration of ecosystem services and
is devoid of any mangroves therefore restoration action provision of benefits for local communities. Successful
must be taken to reintegrate mangroves in the Pulicat ecological restoration of mangrove forests is feasible and
Lake. Palaeo-vegetational records from Pulicat Lake at 4 m has been done on a large scale in various parts of the
(msl) dated to about 7000 years shows 75 per cent world [35]. If we look after these habitats now, then they
mangrove taxa in the area, which is now 18 km inland from will be around with us in future and the economic benefits
the present shoreline [10]. This constant interference will accrue; creating and maintaining an ecological
in mangrove forests has made the system to shrink in an management practice.
alarming way and at a faster rate than inland tropical
forests and coral reefs [17]. A study predicted that ACKNOWLEDGEMENTS
relative sea level rise could be the greatest threat to the
existing mangroves [18]. It will take millions of years to I thank Dr. R. Padmanaban, Dr. Sandeep Sharma and
correct the loss of species and genetic diversity by Dr. N. Parthasarathy for corrections and comments on the
destruction of natural habitats - and we are at the brink of manuscript.
Global J. Environ. Res., 7 (3): 52-55, 2013
54
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Full-text available
  • Oct 2016
The Pulicat Lake is the second largest brackish water lake after Chilika Lake in India. The average area of the water spread is 461 sq km. During the monsoon Pulicat Lake receives freshwater through three major rivers, namely, the Swarnamukhi, the Kalangi and the Arani. The Pulicat lagoon system, which is a storehouse of rich biological resources, is under great threat because of the anthropogenic influences. The Pulicat Lake ecosystem is degraded by siltation, bar mouth dynamics, shell mining and processing and population pressure due to the resettlement of villagers from Sriharikota Island. It has been determined that the extent of the lake, including its water spread area, is decreasing. Therefore, it is essential to assess the land use / land cover changes taking place in and around Pulicat Lake using remote sensing and GIS. Studies on its sediment characteristics are also vital. The grain size content reveals that most of the sediments contain clay and silt in enormous amounts. This lake has been the prime source of a livelihood through fishing for a large section of the population living in the surrounding villages. It is the most important refuge for water birds in south India. The fishing community who lives in and around Pulicat Lake follows the Padu system for fishing in the lake. In this study, apart from studies on configuration changes and sediment analysis, a study of the flora and fauna of the lake and the socio-economic conditions of the local community were also carried out. Finally, mitigation measures for the sustainable protection of the lake’s ecosystem were identified.
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Status and critical knowledge gaps for integrated lagoon management – Pulicat lagoon, India
Article
Full-text available
  • Jul 2015
  • J Coast Conservat
Pulicat lagoon is the semi enclosed and second largest brackish water body in tropical India. The morphology, water quality and biological productivity of the lagoon had being subjected to noteworthy changes over the years under the influence of natural as well as human interference. Recent research have revealed that the lagoon losses its biological integrity due to more sedimentation from rivers predominantly in monsoon seasons, lagoon mouth closure, overfishing, pollution from various phenomena such as usage of motor boats, sewage disposal and aquaculture farms. In this work, evaluation of the status of this lagoon in terms of its biological, physical and chemical importance, its flourishing inheritance, the threats to this ecosystem and the knowledge gaps with the recommendations towards protection of its declining biodiversity are discussed.
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Mangrove Restoration - Costs and Benefits of Successful Ecological Restoration
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Full-text available
ABSTRACT Mangrove Restoration - costs and measures,of successful ecological restoration. Roy R. “Robin” Lewis III, President, Lewis Environmental Services, Inc. P.O. Box 5430, Salt Springs, Florida, USA, 32134-5430. The costs to successfully restore both the vegetative cover and ecological functions of a mangrove forest have been reported to range from USD225/hatoUSD225/ha to USD216,000/ha. Unpublished data would indicate that the even higher costs, as much as USD500,000/ha,hasbeenspentonindividualprojects.Theseareobviouslycostprohibitiveamounts,formostcountriesseekingtorestoredamaged,mangroves.Idividethetypesofmangroverestorationprojectsintothreecategories:(1)plantingalone,(2)hydrologicrestoration,withandwithoutplanting,and(3)excavationorfill,withandwithoutplanting.Thefirsttype,plantingonly,althoughinexpensive(e.g.:USD500,000/ha, has been spent on individual projects. These are obviously cost prohibitive amounts,for most countries seeking to restore damaged,mangroves. I divide the types of mangrove restoration projects into three categories: (1) planting alone, (2) hydrologic restoration, with and without planting, and (3) excavation or fill, with and without planting. The first type, planting only, although inexpensive (e.g.: USD100-200/ha) usually does not succeed,due to a failure to appreciate the physiological tolerances of mangroves to tidal inundation. Even if it works, the result is often replacement of one productive marine habitat, like seagrass meadows with mangroves, a questionable trade-off. The second type, hydrologic restoration, can be done for similar costs, and with proper planning has a high success,rate. Successful restoration of abandoned shrimp
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Mangrove conservation: A global perspective
Article
Full-text available
  • Dec 2012
Mangroves are of great ecological importance and socio-economic significance as a hub for tropical marine biotope. The mangroves are also one of the world’s richest storehouses of biological and genetic diversity. Furthermore, 90 % of the marine organisms spend part of their life in this ecosystem and 80 % of the global fish catches are dependent on mangroves. In addition, mangroves and their associated biota are identified as a promising source of natural and novel drugs. On the other hand, scientific community finds such an ecosystem as one among the world’s most threatened biome due to human intervention in the long past and on-going climate change. Already many countries lost their huge mangrove wealth within the last two decades. Further, decline of the mangrove cover may cause an irreparable damage of ecosystem service to mankind. Now it is high time to conserve the precious ecosystem in order to maintain a stable and healthy coastal environment.
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Evolution of Iskapalli lagoon in Penner delta region, east coast of India - A sedimentological and palynological approach
Article
Full-text available
  • Sep 2005
the Holocene evolution of the Iskapalli lagoon has been reconstructed through landform mapping, vibracore lithology and foraminiferal analysis, supplemented by radiocarbon dating. The characteristics: texture, boundary surface and the palynological assemblages of the lagoon sediments obtained from two cores indicate three distinct sediment units. The lower part of the core (Unit I) consisting of highly (>85%) oxidized coarse sand mixed with shells, moderate bioturbation, high concentration of Spiniferites, Casuarina, fungal spores and algal cysts together with terrestrial herbaceous taxa and sub-parallel lamination suggests deposition in a sandy river mouth bar environment under strang wave influence. The middle part of the core (Unit II) comprising high silty to sandy mud, and parallel laminations together with Protoperidinium sp., Rhizophora and Avicennia indicated low energy lagoonal environment analogous to the modern lagoonal conditions. The upper part of the core (Unit III) consisting of well sorted fine sands with abundant terrestrial taxa are considered to be wind blown sands. The oxidized condition of the distributary mouth bar sediments of Unit I and the occurrence of fine sediments of Unit II suggest the lagoon had witnessed at least one cycle of sea levell fall and rise during the late Holocene between 200 yr BP and 1500 yr BP.
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Biology of Mangroves and Mangrove Ecosystems
Article
Full-text available
  • Dec 2001
  • ADV MAR BIOL
Mangroves are woody plants that grow at the interface between land and sea in tropical and sub-tropical latitudes where they exist in conditions of high salinity, extreme tides, strong winds, high temperatures and muddy, anaerobic soils. There may be no other group of plants with such highly developed morphological and physiological adaptations to extreme conditions.Because of their environment, mangroves are necessarily tolerant of high salt levels and have mechanisms to take up water despite strong osmotic potentials. Some also take up salts, but excrete them through specialized glands in the leaves. Others transfer salts into senescent leaves or store them in the bark or the wood. Still others simply become increasingly conservative in their water use as water salinity increases Morphological specializations include profuse lateral roots that anchor the trees in the loose sediments, exposed aerial roots for gas exchange and viviparous waterdispersed propagules.Mangroves create unique ecological environments that host rich assemblages of species. The muddy or sandy sediments of the mangal are home to a variety of epibenthic, infaunal, and meiofaunal invertebrates Channels within the mangal support communities of phytoplankton, zooplankton and fish. The mangal may play a special role as nursery habitat for juveniles of fish whose adults occupy other habitats (e.g. coral reefs and seagrass beds).Because they are surrounded by loose sediments, the submerged mangroves' roots, trunks and branches are islands of habitat that may attract rich epifaunal communities including bacteria, fungi, macroalgae and invertebrates. The aerial roots, trunks, leaves and branches host other groups of organisms. A number of crab species live among the roots, on the trunks or even forage in the canopy. Insects, reptiles, amphibians, birds and mammals thrive in the habitat and contribute to its unique character.Living at the interface between land and sea, mangroves are well adapted to deal with natural stressors (e.g. temperature, salinity, anoxia, UV). However, because they live close to their tolerance limits, they may be particularly sensitive to disturbances like those created by human activities. Because of their proximity to population centers, mangals have historically been favored sites for sewage disposal. Industrial effluents have contributed to heavy metal contamination in the sediments. Oil from spills and from petroleum production has flowed into many mangals. These insults have had significant negative effects on the mangroves.Habitat destruction through human encroachment has been the primary cause of mangrove loss. Diversion of freshwater for irrigation and land reclamation has destroyed extensive mangrove forests. In the past several decades, numerous tracts of mangrove have been converted for aquaculture, fundamentally altering the nature of the habitat. Measurements reveal alarming levels of mangrove destruction. Some estimates put global loss rates at one million ha y−1, with mangroves in some regions in danger of complete collapse. Heavy historical exploitation of mangroves has left many remaining habitats severely damaged.These impacts are likely to continue, and worsen, as human populations expand further into the mangals. In regions where mangrove removal has produced significant environmental problems, efforts are underway to launch mangrove agroforestry and agriculture projects. Mangrove systems require intensive care to save threatened areas. So far, conservation and management efforts lag behind the destruction; there is still much to learn about proper management and sustainable harvesting of mangrove forests.Mangroves have enormous ecological value. They protect and stabilize coastlines, enrich coastal waters, yield commercial forest products and support coastal fisheries. Mangrove forests are among the world's most productive ecosystems, producing organic carbon well in excess of the ecosystem requirements and contributing significantly to the global carbon cycle. Extracts from mangroves and mangrove-dependent species have proven activity against human, animal and plant pathogens. Mangroves may be further developed as sources of high-value commercial products and fishery resources and as sites for a burgeoning ecotourism industry. Their unique features also make them ideal sites for experimental studies of biodiversity and ecosystem function. Where degraded areas are being revegetated, continued monitoring and thorough assessment must be done to help understand the recovery process. This knowledge will help develop strategies to promote better rehabilitation of degraded mangrove habitats the world over and ensure that these unique ecosystems survive and flourish.
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The Socio-Economic Costs and Benefits of Coastal Habitat Rehabilitation and Creation
Article
  • Dec 1999
  • MAR POLLUT BULL
This paper provides a comprehensive overview of the merits and limitations of using an economics based approach to assess and implement initiatives for coastal habitat rehabilitation and creation. A review of the literature indicates that habitat rehabilitation/creation costs vary widely between and within ecosystems. For coral reefs, costs range from US10,000to6.5million/hectare(ha);1formangrovesUS 10,000 to 6.5 million/hectare (ha);1 for mangroves US 3000–510,000/ha; for seagrasses US9000–680,000/haandforsaltmarshesUS 9000–680,000/ha and for saltmarshes US 2000–160,000/ha. A review of the economic benefits derived from various coastal habitats based on a ‘Total Economic Value’ approach (i.e. accounting for direct and indirect uses, and ‘non-uses’) reveals that many thousands of US$ per hectare could ultimately accrue from their rehabilitation/creation. The paper concludes that despite its limitations, the ‘benefit-cost analysis’ framework can play an important role both in assessing the justification of coastal habitat rehabilitation/creation initiatives, and by helping to improve the overall effectiveness of such initiatives.
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National Trust for Art and Cultural Heritage, New 21 Key concepts in successful Delhi, pp: 27. ecological restoration of mangrove forests
  • Jan 1999
  • R R Lewis
National Trust for Art and Cultural Heritage, New 21. Lewis, R.R., 1999. Key concepts in successful Delhi, pp: 27. ecological restoration of mangrove forests. In:
State of Forest Report
  • Jan 1999
  • K C Ewel
  • C D Field
  • N Kodedam
  • S Y Lee
Forest Survey of India, 1999. State of Forest Report, K.C. Ewel, C.D. Field, N. Kodedam, S.Y. Lee, C. Ministry of Environment and Forests, Dehra Dun, Marchand, L. Nordhanus and Dahdough-Guebas.