STUDY OF BIODIVERSITY AND SOCIOECONOMIC SETUP OF
SUBHAS SAROBAR LAKE, KOLKATA
Sayan Debnath1
AbstractIn this essay an attempt was made to highlight the ecological and recreational role played by
Subhas Sarobar Lake, Kolkata in overall socio-economic development of the city, thus covering
different social, political and ecological aspects associated with the water body. The study is
required to understand how the governing body acts in the management and utilization of the
lake resource system. This essay also gives priority to overall biodiversity study around the lake
and tries to determine the major causes resulting in biodiversity loss. This essay is based on the
literature study with the help of the observation on the behavioural pattern of the local people.
It also spells out the background, basic characteristics and major governing actors to the
resource system.
Keyword— Subhas Sarobar, Biodiversity, Governing body, Ecology, Socio economy
1. Background—
Urban landscape refers to the physical changes happened with a natural ecosystem under the
influence of different anthropogenic activities. These types of activities not only change the
interaction between the animal and plant population but also change the perspective of the
people in respect to the use of the particular resource. For urban development, ecosystem
services are one of the major components that we must look for. The current study considers a
natural ecosystem in the urban area i.e., a lake and how it influences the behaviour of the
people residing around it.
Figure 1: Area of interest
(Source: mypacer.com)
1
Postgraduate Student at TERI School of Advanced Studies ; Email- sayan.debnath@terisas.ac.in
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2. About the lake2.1. Introduction SUBHAS SAROBAR (locally called Beliaghata Lake) situated in the eastern part of Kolkata is
under the administrative control of Kolkata Improvement Trust (KIT). The lake is formed of two
islands in the middle of the water body which makes a proper condition for the diverse species
to sustain their life. The lake is well decorated with perfect mixture of greenery and concretised
structure serving the purpose of giving refreshment to every individual want to take break from
their daily busy routine.
Figure 2: Map of the lake
(Source- Google Map)
2.2.Social settingsThe lake acts like a social hub for the people living eastern part of the city Kolkata and it is
mostly famous for fishing activities, now it is rented to the Department of Fisheries,
Government of West Bengal to provide livelihood among the local people by fishing. Fishing is
opened to everyone but they have to purchase a special ticket from the lake authority to
perform this and the tickets are available in some particular day only. Fishing competition is
also organised by the West Bengal Anglers Association in almost every year, people come from
different districts of the state for participating in it. Beside that it is also famous among the bird
watchers and photographers. Children Park, laughing club and separate jogging path are some
of the reasons for that people for all aged groups come and enjoy the beauty of the nature here
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every day. This place also connects people spiritually as there is a Radha Krishna Temple where
people come and worshiped the god, during the chhath puja a huge number of people
gathering is not an uncommon scenario here.
Figure 3: People carrying fishes in a day of fishing competition
(Source: Anandabazar Patrika,Koushik Ghosh,2019)
Figure 4: Local people performing chhath puja
( Source- times of India,2020)
2.3. Historical Settings –
Subhas Sarobar is an artificial lake made for recreational purpose in the year of 1965 on the
69th birth anniversary of Netaji Subhash Chandra Bose and it is inaugurated by Shri Prafulla
Chandra Sen , Formal chief minister of West Bengal) during A 2nd five-year plan. A lot of debris
was generated in digging out the lake; this debris was used as filling material for the
construction of new road network and buildings in the lake premises.
In 2010, West Bengal Tourism Development Corporation and Kolkata Improvement Trust
decided to convert this place as a tourist spot and proposed total funding of 5 crore for this
beautification project. The main objective of the project is to attract more tourists by building
different facilities like park, joggers’ path, cafeteria, theatre, fountains, food corners etc
without considering the environmental impacts.
In 2014, another project took place which is the East-West Metro Corridor Project undertaken
by Kolkata Metro Railway Corporation Limited. The metro project is encroaching on lake
premises and the construction activities like building of warehouses, parking of dumpers and
stacking of raw materials generates lots of waste making the lake vulnerable for more
environmental degradation. EIA for this metro project is sanctioned by the Department of
Environment of the State of West Bengal but this EIA plan has not been made public. In EIA it is
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mentioned that the project will take all the anti-pollution measures and an executing agency
will monitor several environmental parameters (noise, groundwater level, air quality, water
quality) during the time of the project. But these things are not implemented properly which
continuously affect the lake ecosystem. Public interest litigation (PIL) is also filed by some
residents of Beliaghata, in response to the PIL the Calcutta High Court ordered to stop the
construction activities having no environmental clearance. Despite that, the above mentioned
two projects were completed successfully.
Figure 5: Photos of Children Park
(Source -nomadicgirls.blogspot.com)
3. Resource Settings –
3.1. Size of the Resource System–
The total area is 39.6 ha. including the lake and the surrounding vegetation of which 16.29 ha.
of the area stands for the water body, according to the Outline Development Plan (ODP) of
Calcutta Metropolitan Corporation (1986). The mean length and the mean width of the
resource system is 516 m and 326 m respectively. Total water volume is 634 m3 (in average),
while the mean depth is 4.8 m. The volume and depth of the water body is not constant, it
changes slightly with the change in seasons across the year (Dr. Nihar R. Samal).
3.2. Nature of the Water Body–
Subhas Sarobar is a eutrophic lake which means there is an adequate amount of nutrients
(Phosphorus and Nitrogen) present in the lake which it gets from the surrounding landscapes
due to anthropogenic activities. The presence of these nutrients in high amounts helps to the
exponential growth of phytoplankton and algal population in the lake. Since this type of lake
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can hold a lot of biomass, the amount of decomposition happening in the bottom of the lake is
also high that will lead to less oxygen available for the other aquatic organisms to live.
3.3. Physical Component of the System –
● Temperature - It is the key influencer behind the wide variety of species present in the
lake ecosystem. Every aquatic organism, phytoplankton, macrophytes, zooplankton has
an optimum range of temperature in which they can grow most in numbers. Chemical
reactions are also greatly influenced by it, generally, high temperature is the reason for
more chemical reactions occurring in the water body that lead to release more nutrients
from the sediments. Also, the amount of dissolved oxygen present in the water body
varies greatly with the temperature; water with high temperature can hold less
dissolved oxygen than the water with less temperature (R.A. Khan ; Chandrima Sen). In
Subhas Sarobar, during February to November Thermal Stratification can be observed
that lead to develop two distinct layer of epilimnion (warm water at the top) and
hypolimnion (Cold water at the bottom). Development of these two layer will result in
exclusion of habitat of different organism. As a result of it, there are lot of incidents of
dead fishes noticed particularly in this period.
● LIGHT - It acts as a source of energy for the green plants to perform photosynthesis.
Penetration of light in lake water depends on several factors like the size of the water
body, presence of algal blooms, climate conditions of the surroundings and dissolved
particles. On the depth of the light penetration, we can separate the water body into
Photic and Aphotic Zones. For Subhas Sarobar penetration of sunlight is restricted by
suspended solid particles only at 3m of depth (R.A. Khan ; Chandrima Sen).
● WIND - As the wind blows, it can create turbulence on the surface of the water body. It
circulates suspended particles and nutrients along with the waves and distributes them
all over the lake. The rotation of these nutrients is essential for the organisms living at
the surface. Rate of suspension of solid materials greatly varies with the wind velocity
and it is inversely proportional to each other. In Subhas Sarobar the cycling of nutrient
by wind in different levels beneath the water body helps different organism to grow and
keep on maintaining the food cycle.
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3.4. Biotic Component of The System-
● Phytoplankton(rooted green plants) –
They are the primary producers as well as major photosynthesizes in the lake
ecosystem. The abundance of phytoplankton varies throughout the year due to
temperature variation across all the seasons. Diatoms (Bacillariophyceae), green algae
(Chlorophyceae), blue green algae (Chlorophyceae), phytoflagellates (Euglenophyceae)
are the four types of algae mostly found in the Subhas Sarobar, out of which
Bacillariophycae was found to be most dominant. The average number of
phytoplankton present in this lake is 7656/year while the range varies between
1925/year to 12092/year throughout the year (TAPAN SAHA, 2000).
FAMILY
SCIENTIFIC NAME
Chlorophyceae
Closterium sp.
Scenedesmus sp.
Oedogonium sp.
Spirulina sp
Cosmarium sp.
Ankistrodesmus sp.
Pediastrum sp
Spirogyra sp.
Myxophyceae
Anabaena sp.
Oscillatoria sp.
Phormidium sp.
Nostoc sp.
Lyngbya sp.
Cocconeis sp
Bacillariophyceae
Navicula sp.
Grammatophora sp.
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Achnanthes sp
Amphiprora sp.
Brachysira sp.
Caloneis sp.
Denticula sp.
Fragilaria sp
Euglenophyceae
Volvox sp.
Euglena sp.
● Macrophytes –
Macrophytes (aquatic plants) can be present in three states - submerged, emergent and
free floating. Vallisneria spiralis (submerged), Alternanthera philoxeroides(emergent) and
Enhydrafluctuans(emergent) are the most dominant macrophytes found in Subhas Sarobar.
TYPE
SCIENTIFIC NAME
COMMON NAME
EMERGENT AMPHIBIAN
Alternanthera philoxeroides.
Helencha
Enhydra fluctuans.
Hingcha
Ipomoea aquatic.
Kalmi
Ludwigia adscendens.
Kesaradam
Cyperus platystylis.
Tokapana
C. rotundus.
Tokapana
ANCHORED SUBMERGED
Vallisneria spiralis.
Patasheola
FREE FLOATING
Pistia stratiotes.
Tokapana
Lemna aequinoctialis.
Khudipana
Eichhornia crassipes.
Kachuripana
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● ZOOPLANKTON–
Mostly Zooplanktons are the primary or secondary producers found near the surface.
Like phytoplankton, temperature is the key driving force behind their abundance in the
water body. Zooplankton of the family Rotifera seems to be most diverse and abundant
in the Subhas Sarobar. (TAPAN SAHA, 2000)
FAMILY
Class : Rotifera
Subclass : Eurotaria
Order : Ploimida
SCIENTIFIC NAME
Lecane aculata.
Lecanidae
Lecane (Monostyla) bulla.
Lecane (Lecane) luna luna.
Lecane (Heninostyla) inopinata.
Lecane (Monostyla) unguitata.
Brachionus angularis.
Brachionidae
Brachionus caudatus.
Brachionus falcatus.
Brachionus forficula.
Brachionus quadridentatus.
Brachionus patulus.
Brachionus rubens.
Keratella tropica.
Mytilidae
Mytilina ventralis.
Asplanchna
Asplanchna brightwell.
Trichocerca (Diurella) weberi.
Testudinidae
Testudinella patina.
Synchaetidae
Polyarthra vulgaris.
Filinidae
Filinia opoliensis.
Filinia longiseta.
Philodinidae
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Rotatoria neptunia.
● BENTHOS–
Benthos are the bottom dwelling organisms present in any freshwater lakes, and
exhibit variation in population between 492/m and 4011/m throughout the year in
Subhas Sarobar. Bellamya bengalensis, Thiara tuberculata, Digniostoma cerameoboma,
Branchiurasowerbyi are the most abundant species found here.
CLASS
SCIENTIFIC NAME
Gastropoda
Bellamya bengalensis.
Thiara tuberculata.
Gyraulus convexiusculus.
Digniostoma cerameoboma.
Bivalvia
Lamellidens marginalis.
Oligochaeta
Tubifex sp.
Branchiura sowerbyi.
Limnodrilus sp.
Dipteran Insect
Chironomus sp.
● VERTEBRATE GROUP –
It comprises of different types of birds, fishes and amphibians associated with lake Ecosystem.
Subhas Sarobar is rich in biodiversity with lots of broadleaved trees providing nesting to several
birds. 215 species of flowering plants and 29 species of butterfly are found here. (R.A. Khan ;
Chandrima Sen)
Checklist of BirdsSL NO.
Common name
Family
Scientific name
1
Little Cormoran
Phalacrocoracidae.
Phalacrocorax niger.
2
Indian Shag
Phalacrocoracidae.
Phalacrocorax fuscicollis.
3
Great Cormorant
Phalacrocoracidae.
Phalacrocorax carbo.
4
Indian Pond Heron
Ardeidae
Ardeola grayii.
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5
Asian Openbill-Stork
Ciconiidae
Anastomus oscitans.
6
Black Kite
Accipitridae
Milvus migrans govinda.
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White-breasted’
Rallidae
Amaurornis phoenicurus.
Waterhen
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Common Moorhen
Rallidae
Gallinula chloropus.
9
Blue-throated Barbet
Megalaimidae
Megalaima haemacephala.
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Red-vented Bulbul
Passerines
Pycnonotus caler.
Checklist of FishSL. No.
Scientific name
Local Name
Family
1
Labeo bata.
Bata
Cyprinidae
2
Puntius sophore.
Puti
sophore
3
Anguilla bengalensis.
Banehara
Anguillidae
4
Gudusia chapra.
Challa
Clupeidae
5
Amblypharyngodon microlepis.
Mola
Cyprinidae
6
Catla catla.
Catla
Cyprinidae
7
Labeo rohita.
Rui
Cyprinidae
Checklist of Flowering plants –
SL. NO.
Scientific Name
Family
Common Name
1
Abutilon indicum.
Malvaceae
Potari
2
Acacia auriculiformis.
Mimosaceae
Bengali Babul
3
Acalypha indica.
Euphorbiaceae
Mukta Jhuri
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4
Achyranthes aspera.
Amaranthaceae
Apamarga
5
Ageratum conyzoides .
Asteraceae
Uchunti
6
Alocasia indica.
Araceae
Mankachu
7
Alstonia scholaris.
Apocynaceae
Chhatim
8
Alternanthera
paronychioides.
Amaranthaceae
Sessile joyweed
9
Alternanthera philoxeroides.
Amaranthaceae
Danta
10
Alternanthera sessilis.
Amaranthaceae
Mati kanduri
Amaranthus spinosus.
Amaranthaceae
Kantanotya
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Amaranthus viridis.
Amaranthaceae
Data
13
Sida acuta.
Malvaceae
Morning mallow
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Sida rhombifolia.
Malvaceae
Jelly leaf
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Solanum nigrum
Solanaceae
Kakmachi
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4. Factors affecting Biodiversity –
1.
Invasive Species- Invasive species is a nonnative species to a particular area which
can quickly adapt to a new ecosystem, compete with the native species for habitat
and food and make it difficult for them to survive. In the case of subhas Sarobar and
other lakes in the city, we can see the population of these invasive species growing
exponentially and altering the environment. One of the common invasive sp. found in
this area is Crocodile fish which is an ornamental fish. Curban gar, which is native to
Central America (Carnivore) was also found in the lake a few years back. The reason
behind the availability of these fishes in our neighbour water bodies is the result of
carelessness of the aquarium traders. These fishes have high demand in the market,
traders import the fish from foreign countries and make them breed in controlled
environments. But when they grow big, they just release them in the neighbouring
water bodies without considering the environmental consequences. Rapidly growing
populations of these species can make our food chain more vulnerable and can also
cause loss of the economic benefits which we get from the lake.
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Figure 6: A man holding the invasive fish ( Curban gar.)
(Source – The logical Indian, 2016)
2.
Anthropogenic Activities - Open Spaces, greenery and the water body attract a lot of
people around the city to the place that’s why human pressure is increasing day by
day. More than 3000 local people per day come to this place and the lake water is
extensively used for washing clothes and bathing by local people. This activity can
lead to eutrophication which is dangerous to the fish population to survive. After
Chhath Puja, the lake turned into a dump yard after being extremely polluted with
plastics and puja materials. As a result of these activities populations of birds and
fishes are already declining for the last three years.
Figure 7: People involve in bathing and washing their clothes
(Source – Telegraph India, 2017)
Figure 8: Condition of the lake a day after Chhat Puja
( Source - Telegraph India,2018)
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5. RESOURCE SERVICES (ECOSYSTEM SERVICE FRAMEWORK)Ecosystem Service framework points out the different role played by the healthy ecosystem
that can help to overall economic development and betterment of human lifestyle if we are
able to take care of it by proper environment management strategies.
6. GOVERNING ACTORS –
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● Kolkata Improvement Trust (KIT) is a governing body, initially known as Calcutta
Improvement Trust (CIT) established by the government of West Bengal in 1911. It
worked as an independent entity for 106 years intending to make proper urban planning
and development for the city. In 2017, it was merged with the Kolkata Metropolitan
Development Authority (KMDA) for better management and implementation of
different policies.
This is the major encouraging body behind the beautification project and proposed for building
of the floating museum, separate jogging and cycling track for engaging more people with the
place. It maintains the quality of water body suitable for the aquatic organism by putting a ban
on the bathing, washing clothes and improving the sewerage and drainage network.
● Kolkata Metropolitan Development Authority is a government body, helps to implement
plans proposed by a state government or central government. They are in charge of
applying the strategies regarding the conservation of water and other physical natural
resources.
● Kolkata Nagarik Sammelan Kolkata Nagarik Sammelan is a governing body trying to find root causes for any issues
concerning the development of Kolkata and making a strong citizen movement within the city.
They already sent a letter to West Bengal Pollution Control Board in the demand of declaring
the lake as a “National Lake”, restoring the area which is already being damaged because of
construction activity and also abandoning the current beautification project.
● Anglers Association is a non-profit organization which looks after the fishes in the
Subhas Sarobar on a lease basis.
7. Governing Mechanism –
Development and Upkeepment Plan is a joint venture project between Kolkata Metropolitan
Development Authority and Kolkata Improvement Trust. This Plan mainly focused on the
maintenance of the ecological integrity of the lake and its adjacent land and came up with
several strategies for betterment of the water quality. This plan put restrictions on the dumping
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of solid waste generated from any rituals, immersion of idols, washing of vehicles (Municipal
and Industrial waste carrying vehicles) and on bathing.
8. OUTCOMESThe governing bodies which have stake in this lake are most of state and local level. KMDA and
KIT are the major governing body works here together; their plans and strategies focus more on
the economical use of the water body rather than conservation of the lake ecosystem. After
chhath puja in 2019, the municipal corporation come into act of making the place waste free
after the 1 day which was not with the case with Rabindra Sarobar situated in the southern part
of the city that reflects some kind of lack in coordination between governing bodies in the case
of Subhas Sarobar. Sanctioning of metro railway path beside the water body in the lake
premises also put a question in the decision taken by the State Govt. because this project not
only can be the reason for biodiversity loss but also degrade the aesthetic beauty of the lake
due to the increment in pollution. This project also interrupts the outcome of the beautification
project. Coordination from the local people is also poses problems in the implementation of the
rules properly, because there is no change observed in the pattern of using the water after
banning on several anthropogenic activities.
9. DISCUSSION -
This Study revealed that the lake is quite rich in biodiversity as more than 20 species of
phytoplankton and 17 species of flora found in water body and land respectively. The lake has a
high productivity rate proving that the water is eutrophic in nature. But the use of water in an
unsustainable manner is one of the major causes of water quality degradation. Though the
governing bodies come up with several plans and strategies for conversation of the lake water
but due to the pressure of local political bodies, the plans are yet to implement properly. The
condition of the lake after the Chhath puja is the proper example of the poor implementation
of the strategies. During the lockdown the lake was closed for 6 months to the common people
and now the visiting hours is reduced to 6 hours/day which helps to reduce the public gathering
and also helps in healing of the environment conditions. Raising awareness between people
regarding the importance of this urban lake, change in pattern of coordination, resource use
and monitoring among different authorities is mostly needed for sustainability of the lake.
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ACKNOWLEDGEMENT –
I would like to express my special thanks to my professor Dr. Mansee Bal bhargava for her
valuable guidance and support and for giving me this golden opportunity to build this case
study. This project would not have completed without her enormous help and worthy
experience.
Secondly I would like to thanks my friends for their valuable suggestions in completing my
project.
REFERENCE -
Chameli Ghosh, T. R. (2013). Utilities of Urban Ecological Units - a comparative study of Rabindra
Sarobar and Subhas Sarobar, Kolkata. indian journal of Spatial Sciences .
Dr. Nihar R. Samal. Effect of meteorological forcing and stratification variability in three
morphometrically different urban lakes in Kolkata Metro city.
R.A. Khan ; Chandrima Sen. (n.d.). Studies on Physiochemical and biological properties of two man made
lake,Kolkata. 2002 .
TAPAN SAHA. (2000).Monitoring on Environmental Status of Subhas Sarobar ,Calcutta and Preperation
of management action plan.
AuthorSayan Debnath is a student of TERI School of Advanced studies, currently pursuing Masters in
Water Science and Governance. Learning about water planning, it's management, and also
about relationship between gender and water. He is highly enthusiastic in grasping a lot of
knowledge related to water sector and also eager to brainstorm and ideate solutions for real
life problems. He also has a mission to build awareness among people and motivate them to
think for water in near future.
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