Coastal
ecosystem – features, constraints and future suggestions: an overview1
H.S.Sen
President, Indian Society
of Coastal Agricultural Research
Abstract
Coastal ecosystem poses a delicate
equilibrium between land and water masses amongst its different components but
with high degree of vulnerability in spite of bountiful natural resources. The
equilibrium is further under serious threat due to climate change and global
warming. On the other hand, it is significant that coastal marshes tend to
sequester carbon continuously with increasing storage capacity and with time,
and thus regarded as a valuable C sink per unit area, particularly in the
tropics, to negate adverse impacts due to global warming. Planning for
effective and sustainable development warrants specific attention to maintain
the equilibrium. This will require adoption of integrated approach to soil and
water management, in the first place, and through it or otherwise, necessary
measures to conserve the ecology. Piecemeal approaches to reclaim location
specific problems or interference with the hydrology of the rivers per se for
short term gains for increase of productivity or otherwise, disregarding
completely the practices on integrated management of different intervention
areas and thereby conserve the ecology in coastal plains, may offset the
equilibrium, as experienced in different parts of the world, leading to such
adverse impacts, such as seawater intrusion into inland areas, massive loss of
mangroves, coral reefs, seagrasses and various other aquatic plant & animal
species, sedimentation & erosion, tidal flooding, subsidence of land, etc.
The influx of reckless application with
fast increasing dose of nitrogen or other inputs resulting in nutrient
imbalance through human activities in the adjoining inland and coastal areas
are glaring examples leading to such phenomena as eutrophication and formation
of dead-end zones in the coastal water bodies.
Policy approach for water budgeting of
different water resources, preferably on watershed basis, with minimal or
planned dependence on abstraction of the underground water should be an
essential strategy to be drawn in order to ensure sustainable increase in crop
water productivity as well as water productivity in other sectors all along the
coast.
It is emphasized that GoI has the scope to
develop more comprehensive climate change policies to mitigate weather
adversities causing colossal loss due to impacts of the natural disasters.
There is a need for development and validation of location
specific rice-based diversified farming models for both east and west coasts of
the country. These models should be cost-effective and environmentally
sustainable and can optimize utilization of natural and human resources.
Dissemination of rice-based farming systems will need support facilities in
terms of capacity building partnership development, market intelligence and
micro-finance.
It is strongly urged
to explore and exploit non-farm actions, be it ecotourism or beyond, seriously,
alongside application of on-farm activities, to improve livelihood sustainably
with full protection to ecology of the area in the coastal ecosystem.
__________________________________________________________________________________
1
12th National
Symposium on 12th National Symposium of ISCAR on
“Coastal Agriculture: Boosting Production Potential under Stressed Environment”
at Dr.B.S.Konkan Krishi Viswavidyapith, Dapoli on 28 September-1 October 2018
Distinguished
delegates and Guests, wish you all on behalf of the Indian Society of Coastal
Agricultural Research a happy good morning.
‘Coastal
plain’ is the landward extension of the continental shelf or the sea and
commonly used for agriculture and allied activities as well as for few other
occupational purposes, but is generally distinctly differentiated from other
‘main’ components, viz. estuaries,
coral reefs, salt marshes, mangrove swamps, macrophyte dominated regions,
continental shelves, etc. Rather, coastal plains may, in
some cases, include few such main components within its spatial boundary, and
are in dynamic equilibrium with each other, together present the ‘coastal
ecosystem’. In other words, though at a given time the area under each
component is well demarcated and thus areas may be estimated with some degree
of precision, it may alter, even considerably, over a long time from one
component to another or vice versa because of geomorphologic changes due either
to or a combination of climatic, hydrological, geological and anthropogenic
factors, in support of which there are plenty of examples all over the globe.
This suggests its vulnerable nature, in other words stability of the coastal
ecosystem at large, extent of which is much more than other ecosystems.
Stability of the ecosystem should be of vital importance for the very high
population density living along the coast.
Of the four
factors mentioned above, possibly nothing can be done to control the geological
factors in order to mitigate the vulnerability of the ecosystem except taking
indirect measures by avoidance through advance message network, while for
factors related to climatic phenomenon, increasingly gaining importance due to
global warming, little can be done to contain it so far, and for the other two
some exercises may possibly be undertaken to improve stability location-wise as
well as globally. It should be worth to gauge the vulnerability or stability of
the coastal ecosystem – its method and the extent, the factors affecting it and
future predictions, and the nature of influence on the ecological balance at
large including soil & water salinity, cropping system, and biogeochemical
characteristics of the coasts, and finally suggest the adaption measures. This
calls for a new concept for integrated coastal area development, the main fulcrum
of which should rest on the scope to improve the stability of the ecosystem on
a temporal scale, the impact of global warming notwithstanding.
Coastal areas in India and
elsewhere are by and large heavily populated. Nearly 40 % of cities larger than
500,000 population in India are located in the coast. Overall about 50-70 % of
the global population live within 100 km of the coastline covering only about 4
% of earth’s land (Poyya and Balachandran, 2008), thereby drawing heavily on
coastal and marine habitats for food, building sites, transportation,
recreational areas, and waste disposal. According to another estimate (Wikipedia,
2009), coastal areas (within 200 km from the sea) share less than 15 % of the
earth surface area, and this predicts that three-fourths of the world
population are expected to reside in the coastal areas by 2025. It is important
that coastal ecosystems have an economic value beyond their aesthetic benefit
supporting human lives and livelihoods. By one estimate (Poyya and
Balachandran, 2008), the combined global value of goods and services from
coastal ecosystems is about US$ 12-14 trillion annually--a figure larger than
the United States' Gross Domestic Product worked out in 2004. Notwithstanding these
facts, the areas face a
number of challenging areas worth
consideration for planned development, and these include a series of
constraints threatening productivity in agriculture and allied areas, the very
base for the livelihood of the poverty-stricken inhabitants, human and climate
induced factors threatening the ecological sustenance, and catastrophic effects
of the weather disaster, which further aggravates due to climate change phenomenon.
If the strength in this ecosystem rests with bountiful natural resources the
weakness also lies in the same and its unplanned and arbitrary use, deserving
therefore appropriate and scientific exploitation, in the first place, of the
land and water preferably in an integrated fashion.
Definition
and delineation of coastal areas
As per
the 1991 notification, the Coastal Regulation Zone (CRZ) in India extends upto
500 km from the high tides and includes the land between high tides and low
tide lines. The ecosystem thus includes saline, brackish (mixed saline and
fresh) and fresh waters, as well as coastlines and the adjacent lands, the
latter being the landward extension or the coastal plain. The different components,
like estuaries, macrophyte communities, mangroves, coral reefs, salt marshes
and the remaining continental shelves normally present in the coastal ecosystem,
are in dynamic equilibrium and believed to be highly vulnerable to any change
in the system. Velayutham et al.
(1998) for the first time made a scientific attempt to characterize soil
resources and their potentials of the coastal plains belonging to different
Agro-ecological Sub Regions (AESR) in India showing a total of 10.78 million
hectare area including the islands. Delineations made by them need to be
further refined with due consideration to the prevalence of biota or their remnants,
an all-important parameter, in the ecosystem.
Technological constraints
Different factors limiting
agricultural productivity as well as ecological sustenance of the coastal
plains are listed as (1) Excess accumulation of soluble salts and alkalinity in
soil, (2) Pre-dominance of acid sulphate soils, (3) Toxicity and deficiency of
nutrients in soils, (4) Drainage congestion particularly in lowlying areas, (5)
Inadequate availability of good quality water suitable for irrigation, (6) Intrusion
of seawater into coastal aquifers, (6) Shallow depth to underground water table
generally rich in salts, (7) Periodic inundation of soil surface by the tidal
water vis-à-vis climatic disaster and their influence on soil properties, (8)
Heavy soil texture and poor infiltrability of soil, (9) Eutrophication, hypoxia
and nutrient imbalance, (10) Erosion and sedimentation of soil, and (11) High
population density, etc.
A number of location
specific studies have been conducted for the management of coastal stressed
soils for higher agricultural productivity through drainage &
desalinization of water congested areas particularly in the lowlying belts
through adoption of appropriate sub-surface drainage or through suitable land
shaping technique, leaching of excess soluble salts in saline soils,
reclamation of acid sulphate and sodic soils, and remedial measures of the nutritional
disorders, etc. Methods developed for each will be sustainable in the long run
if due attention is paid to integrated practices of land and water resources and
through it or otherwise the necessary measures to conserve ecology at the same
time.
Soil health & carbon
sequestration
The
importance of improved soil quality in the coastal plains through higher SOC
level of the soils is established. IRRI characterized lowland rice soils
(excluding deepwater rice) in Asia in respect of soil quality (Haefele and
Hijmans, 2009), which includes large areas under coastal plains. They grouped
soil qualities into four categories. These were: Good, Poor, Very Poor and
Problem soils. ‘Good’ and ‘Poor soils’ represent those with different degrees
of weathering but without major constraints; ‘Very Poor’ represents soils with
multiple chemical constraints (acidity, deficiency of phosphorous, or
toxicities of iron and aluminum); while ‘Problem soils’ represent those with the
most frequently cited soil problems, including acid sulphate, peat, saline, and
alkaline soils, which partly cause low fertility, and partly soil chemical
toxicity.
Modeling C sequestration so
far indicated that coastal marsh ecosystems tend to sequester C
continuously with increasing storage capacity as marsh age
progresses and its area increases. Thus, C sequestration in coastal
marsh ecosystems under positive accretionary balance acts as a negative
feedback mechanism to global warming.
Choi and Wang (2004) were of the opinion that dynamics of carbon cycling
in coastal wetlands and its response to sea level change associated with global
warming is still poorly understood. However, they also observed during their
study at Florida that salt marshes in this area have been and continue to be a
sink for atmospheric carbon dioxide. Because of higher rates of C sequestration
and lower CH4 emissions, coastal wetlands could be more valuable C
sinks per unit area than other ecosystems in a warmer world. Brigham et al. (2006) stated that the estuarine
wetlands sequester carbon at a rate about 10-fold higher on an area basis than
any other wetland ecosystem due to high sedimentation rates, high soil carbon content,
and constant burial due to sea level rise.
In India, possibly, the
first ever study made by Bhattacharyya et
al. (2000) more than a decade back showed SOC pool in two soil strata under
different physiographic regions including coastal areas. The data based on soil
analyses covering 43 soil series showed the SOC data varied from 2.4 Pg to 10.9
Pg from 30 cm to 150 cm soil depth. It will be prudent to concentrate on
elaborate studies in future on monitoring SOC pool in different soil strata in
coastal areas over a long period of time, and
relate them with
sea level rise,
extent and nature
of land submergence with water,
seawater quality, extent and nature of vegetative cover, relevant soil and
climatic parameters, nature and amount of agricultural, industrial and city
effluents discharged into the sea, and any other anthropogenic factors of the
locality likely to influence SOC, etc. It should also be possible to create a databank
on SOC and related factors of the long time past using radiocarbon dating.
Integrated soil & water
management
If the water table, rich in
salts, is present at a very shallow depth (generally not exceeding a depth of 2 m below the soil surface), it
contributes salts to the root zone during the dry season through upward
capillary rise in response to evapotranspiration demand of soil moisture. The
net salt loading in the root zone will be positive (salinity will build up) or
negative (desalinization will take place) depending upon the relative rate of
recharge of salts by upward rise to rate of downward flux of salts through
leaching. The relative salt loading will thus be treated generally as positive
during dry season, and negative (waterlogging on the soil surface) during wet
season due to high rainfall, and the process will be repeated in each year in a
seasonally cyclic mode.
Working models have been
developed, even for small holdings dominating the coastal ecosystem, based on
the hydrological processes, and the same validated for different agro-climatic
regions in India for (i) computation of soil water balance, (ii) optimal design
of water storage in the ‘On-farm reservoir (OFR)’ by converting 20 % of the
watershed, (iii) design of surface drainage in deep waterlogged areas to reduce
water congestion in 75 % of the area, and (iv) design of a simple linear programme
to propose optimal land allocation under various constraints of land, water or
other critical inputs to arrive at a contingency plan for maximization of
profit. It has also been reported to use remote sensing and GIS in mapping
lowland lands and performance assessment of irrigation/ drainage systems
(Ambast and Sen, 2006).
Irrigation
water resources
In spite of the coastal
ecosystem presenting a delicate equilibrium among the different components
there is however no firm strategy, as of now, for exploitation of water
resources for irrigation and other purposes for long term solution in any
sector. Planning should be such as not to disturb the ecosystem in the long
run. It is suggested that location-specific
programme on water allocation under different
sources should
be drawn up for each region, based on soil, climate, water, and crop
parameters, as well as their spatial variations, as per appropriate strategies
to be worked out,
with minimal dependence on abstraction of water from the underground aquifer,
but with increasing dependence on other means, like use of surface water
sources by recycling of rainwater stored and fresh water available using
innovative seawater desalination technology, and conjunctive use of marginally
saline water available, with overall target to increase water productivity and cropping intensity phasewise, and conserve the
ecosystem at the same time. Future vision
on water budgeting in the coastal areas in India, which should be the crux towards
planning for integrated and efficient land and water management practices, along
with conceptualizing a model specifically designed for water budgeting for the
coastal watersheds including all its components, have been worked out recently to
ensure long term sustenance by Sen and co-workers.
Seawater
intrusion into inland areas may be minimized, if not to be eliminated
altogether, through structural measures or with the help of ‘Optimization
Models’, the latter however yet to be validated through testing under wide
variety of situations in order to suggest optimal location of pumping with
reference to the coast, rate & frequency of pumping of underground water,
etc.
Agri-horti production system
The coastal areas in countries like India are
endowed with abundant sunshine, solar as well as wind energy, precipitation,
diverse soils, physiography, climate, etc. and therefore, have tremendous
opportunities for supporting a host of perennial and annual crops like trees,
fruit plants, cereals, root crops, pulses, oilseeds, commercial crops,
vegetables, etc. In addition, prospects of fishery, poultry, animal husbandry,
sericulture, mushroom cultivation, bee-keeping and dairying are also enormous.
Rice-based cropping systems are more dominant in the coastal plain tracts. In a field experiment on deep poorly drained
alluvial soil in Balipatna Block in Odisha having average annual rainfall of
1480 mm, a modified soil physical environment through 5m x 30m alternate raised
and sunken beds was studied in 2002-04 for seven different cropping systems.
The highest rice equivalent, water expense efficiency, net water productivity,
net returns, and B/C ratio were achieved with rice-fish in the sunken bed and
pointed gourd + snake gourd in the raised bed system. Many developing countries
in Asia, Africa and Latin America are reported to possess rich genetic
resources of tuber and root crops, and there is significant opportunity for
exchange of plant genetic materials.
Certain plantation crops, especially coconut,
arecanut and cocoa have received major attention in the coastal areas. Mixed and intercrops in the coconut and
arecanut based cropping system have helped in augmenting overall production
capacity as well as in improving economic returns of the farmers in a
sustainable manner. The coconut-based farming system comprising coconut, grass,
dairy, poultry and fishery has proved more economical and sustainable. Several
benefits relating to sustainability and profitability accruing from diversified
and integrated farming are as under:
¨
Efficient conservation and
optimization of natural resources
¨
Productive recycling of organic wastes
among different components of farming system
¨
Enhancement of soil health including
organic carbon status and microbial activity
¨
Prevention / minimization of soil
erosion and other land degradation hazards
¨
Improvement of soil productivity
capacity
¨
Reduction in use of external inputs
and hence, less crop production cost
¨
Increased environmental and ecological
safety
¨
Meeting multiple demands relating to
fodder, feed, food, fibre, fertilizer, fuel, timber, medicine, etc.
¨
Greater employment, livelihood and
nutritional opportunities
¨
Regular flow of higher income leading
to poverty alleviation
¨
Insulation of farmers against risks arising
from calamities, such as drought, weather abberation, pest virulence, etc.
¨
Security of greater self reliance
among farming community
¨
Ecological and biological stability of
natural resources as well as of productivity
Cropping
systems
Almost the entire coastal area is grown with
rice, mostly rainfed, under different land situations depending upon level of
soil salinity, topography, and depth to waterlogging often subjected to floods.
The elite rice varieties developed, identified so far (as per personal
communication received from CSSRI, Regional Station Canning, WB) are summarized
as:
Upland (Salinity ECe 6-9 dSm-1,
waterlogging up to 0-20 cm): Canning 7, CSR-4 (Mohan), CSR-36, Bidhan-2,
CST 7-1
Medium
land (Salinity 6-8 dSm-1, waterlogging up to 0-30 cm): CSR 1 (Damodar), CSR 2 (Dasal), CSR 3 (Getu), Talmugur,
Nona-Bokra, CSRC(S) 21-2-5-B-1-1 (IET-17343/Namita-Dipti), IR-72046, CSRC(S)
2-1-7 (IET 13428/Sumati), CSRC(S) 11-5-0-2 (Utpala), CSRC (S) 5-2-2-5
(IET12855/Bhutnath), Nonasail selection (CSR 6)
Medium lowland (Salinity ECe 5-7 dSm-1, waterlogging up
to 30-40 cm): SR 26B, CSRC(S) 7-1-4 (IET 18250/Amal Mana),
Sabita, Patnai 23
Lowland (Salinity ECe 4-6 dSm-1, waterlogging upto
40-60 cm): Malabati, Kalamota, Sadamota (Selection),
Tilak Kachari, FR 13A, IR 72046, NC-678, Asfal, Najani, Kumragour
The total cultivated area in the eastern
coastal plain is about 8.58 million hectares with a cropping intensity of 134%.
Rice-based production system is the major form of land utilization pattern.
Important crops and cropping pattern prevalent in different States in eastern
coastal plain are listed in Table 1.
Although West coast
region receives higher rainfall, many places experience severe scarcity of
water during summer months as the rainfall is concentrated during four months
of the monsoon period. The coastal plains and valleys of the region are
dominated by rice and rice-based cropping systems. The
rice-based cropping systems include rice-cowpea (Alsando), rice-groundnut under residual moisture situations in rice
fallows from early December to March and rice-vegetables, rice- sweet potato in
areas where life-saving irrigation can be provided by traditionally developed
sunken wells in rice lands mostly in khar
lands. These constitute the predominant cropping pattern, which dominates
nearly 39-40 percent of the agrarian scenario in the region. Besides, there are
high prospects for plantation and horticultural crops, both as sole crops as
well as inter- or mixed crops, in the region from both
Table
1. Important crops and cropping systems in coastal ecosystem of different
States of Eastern India (Saha et al.,
2008)
State
|
Field Crops
Wet season Dry season
|
Andhra
Pradesh
|
Rice, cotton, sugarcane, tobacco, groundnut
|
Blackgram, greengram, groundnut, chilli
|
Odisha
|
Rice, jute, sugarcane
|
Rice, blackgram, greengram, chilli groundnut, sunflower
|
Tamil
Nadu
|
Rice, sugarcane, sorghum, pearl millet, tapioca
|
Rice, groundnut, cotton
|
West
Bengal
|
Rice, jute
|
Rice, barley, lathyrus, sunflower, sugarbeet, chilli, watermelon
|
commercial and ecological points of
view. Exploitation of value addition of a number of these crops adds to their
commercial interest. In Goa alone, an
area of 99,672 ha (58% of the total cropped area) is under horticultural crops
and there is an increasing trend during recent past both in area (5.53%) and
production (6.19%). The plantation crops of the region include coconut, cashew,
arecanut, oilpalm, rubber, banana, pineapple, vanilla, ginger, turmeric, black
pepper and a number of other spice crops. Besides, there high prospects
of a number of vegetable and fruit crops.
Livestock Production System
Coastal areas offer scope for farm
diversification through integration of horticultural crops, aquaculture,
livestock, agro-forestry and other enterprises in rice ecologies. Such an
approach can be a strategic road-map towards food, nutritional, income and
employment security in the fragile coastal ecosystem. Farming system approach used in the west coast for coconut garden, for
example, involves cultivation of
fodder grass in the interspaces of coconut palms, maintenance of milch
animals and recycling of cattle manure in the coconut-fodder-pepper mixed crops
stand. This model (Sen et al., 2010) generated
additional employment to the tune of 356 mandays and ensured better returns
without any yield decline in coconut. Some examples are cited below especially suitable
for the east coast.
Dairy farming
The total milk produced by the coastal states
of India is quite significant. Some of the major milk production centers of the
country are located in coastal parts of Gujarat, Andhra Pradesh, and Tamil
Nadu. The higher milk production in these regions may be attributed to the
better animal management practices, availability of feed and fodder, efficient
milk procurement and processing facilities. Dairy farming may be an attractive
option for farmers and will contribute to ensuring economic and nutritional
security. Certain region-specific dairy products like chhana based sweets (e.g. rasogolla
and sandesh) though originated in
West Bengal and Odisha, have become popular throughout the country (Sen et al., 2010).
Rice-duck farming
Duck
rearing in rice field is a profitable and environmentally sustainable farming
option and is practised in some Asian countries. Ducklings (7-20 days old) can
be released at 200-400 per ha in the rice field after 10-20 days of planting
and can be raised till flowering of the crop. After the rice harvest, ducks may
be allowed to again forage in the field. On-farm demonstration trials on rice-duck farming in northeastern and
southern regions of Bangladesh, showed feasibility of rice-duck system as well
as benefits in terms of about 20% higher yield of rice and 50% higher net
return compared to sole rice farming. Moreover, this system can improve
nutritional status of the resource poor farmers besides, opportunities of
women’ participation (Sen et al.,
2010).
Rice-fish production systems
Rice-fish farming technology options
are available for various waterlogged and salt affected ecologies in both east
and west coasts of the country. The mixed or concurrent rice-fish-prawn and
rice-fish-horticulture-livestock based diversified farming systems are suitable
in non-saline waterlogged and deepwater and low to moderately saline areas.
While, mixed, sequential and rotational rice-fish-/ prawn culture can be
practised in flood plains and medium to high saline ecologies. Other
remunerative crops and animal-based components can also be integrated for
higher farm productivity, income and employment.
The rice-fish fingerlings production
system is feasible in irrigated and shallow favourable lowlands with production
potential of about 3-12 t ha -1 of rice (two crops) and 100-300 kg
fish fingerlings in a season.
Rice-grow-out fish-prawn mixed culture
can produce about 2-10.0 tha-1 of rice grain (two crops) and
200-1200 kg fish ha-1 yr-1. The net income in rice-fish farming is Rs
6,895-10,781 ha -1, as compared to Rs 4,037 ha-1 from
rice alone. Integration of vegetables and fruit crops on bunds can further increase the productivity and net farm income to
the tune of Rs 22,450 ha -1 yr-1 (Sen et al., 2010).
Rice- fish diversified farming systems
The Central Rice Research Institute,
Cuttack, Odisha has developed adoptable technology models for rainfed
medium-deep lowlands (upto 50 cm water depth) and deepwater (500-100 cm water
depth) situations. Components such as improved rice varieties, fish, prawn,
ducks, Azolla, and other crops (pulses, oil seeds, vegetables,
watermelon) after wet season rice in the main field and vegetables, fruit
crops, floriculture, apiculture, mushroom, agro-forestry, poultry and goatery,
etc. on bunds are grown in rainfed
waterlogged areas. In deepwater areas,
multitier farming system can be practised with the components like, different
short term and perennial fruit crops in tier I (upland), tuber crops and vegetables in tier II (upland), rainfed
lowland rice (tier III) followed by crops like sweet potato, pulses, oilseeds, vegetables,
watermelon and deepwater rice (tier IV) followed by rice and vegetables in
the field. Fish and prawn are grown along with rice crop
during wet season and later in the connected pond refuge (micro-watershed)
during winter and summer seasons. Poultry, duckery, agro-forestry, fruit and
plantation crops and other components are taken up on bunds of the system.
The
productivity in the rice- fish diversified farming systems ranges from 16-18 t of food crops, 600-1000 kg of fish
and prawn, 500-700 kg of meat and 8,000-12,000 eggs in addition to flowers,
fuel and fibre wood and rice straw and other crop residues as feeds for
livestock from one hectare of farm area. These systems can annually generate a
net income of Rs 40,000-1,30,000 depending upon the components and level of
their management besides, additional employment of 250-300 man-days over rice
farming. This farming system can
increase farm productivity up to 15 times, income up to 20 folds and employment
by two times over mono-cropping of rice. Adoption of the system in coastal
plains of Odisha, resulted about 15 times increase in net farm income, besides
higher employment generation. At CSSRI, Regional Station Canning (WB) economic
evaluation was made for diversified cropping system under OFR (on-farm
reservoir) technology, developed and subsequently tested in farmers’ fields at
a village site located at Canning. The additional incomes, in additional to
normal practice of rainfed kharif
rice alone, accrued per hectare were to the tune of Rs.440/- due to growing of
plantation crops on the bunds, while
the values were Rs. 2525/- and Rs.12,000/- on account of pisciculture in the
storage reservoir with and without bund
around it, respectively (Sen et al.,
2010).
Coastal
saline ecologies
The rice-fish production systems in
coastal saline ecology include mixed farming of salt tolerant lowland rice crop
and freshwater fish and prawn after proper desalinization of field with rain
water during wet season followed by salt water fish and prawn farming during
dry season. The productivity in this system ranges from 3.0-4.0 t ha-1of
rice and 500-600 kg ha-1 of fish and prawn during wet season and
400-600 kg ha-1 of salt water fish and prawn during dry season. The
net income is in between Rs 8,000-23,000 ha-1yr-1 compared to Rs
5,100 ha-1yr-1 in the case of rice (wet season crop)
alone. The income increases to about Rs 33,000 ha-1 yr-1
with the addition of vegetable crops during wet season. Sequential and
rotational rice-fish farming systems are suitable for coastal wet lands/flood
plains. In these systems, fish culture is done during wet season and rice crop
(improved varieties) is grown during dry season. The productivity ranges from
3.3-7.0 t ha-1 in the case of rice and 350-1600kg ha-1yr-1
in case of fish with net income of Rs 25,000-62,000 ha-1yr-1.
The rotational rice-fish system enhances farm income by about 72% over the
traditional farming in flood prone areas of coastal Kerala. Rice-fish culture
in mono-cropped coastal saline rice fields of high rainfall region of
Bangladesh provided higher farm income (cost/benefit ratio, 1.6-2.79 vs 1.87 in rice mono-cropping), in
addition to large potential of fish (tilapia) fingerling production in coastal
paddy fields.
Rice-fish farming accrues many benefits such as
cost-effectiveness, higher rice bio-mass yield and environmental
sustainability, as there are reports of 50% decrease in water salinity after
five years in fish refuge/ micro-watershed and reduction of greenhouse gases to the level of 30%
in CH4 (Lu and Li , 2006) and
32% in N2O.
Poultry birds’ rearing is another profitable
option in coastal areas. Small scale backyard poultry farming with coloured
dual purpose birds in super-cyclone affected coastal Odisha, provided a net
profit of about Rs 350 per bird, besides eggs to the poor farm families.
Among other alternative farming systems,
environmentally sustainable shrimp farming as per the guidelines of Coastal
Aquaculture Authority Act, 2005 and mud crab culture are the highly profitable
options. Shrimp farming can provide a productivity of about 1.5 t and net income of Rs 1.66,000 ha-1 yr-1, while mud crab fattening
can give a very high annual net farm income of Rs 1,41,800 by raising six cycles of
crop in a 0.1 ha tidal pond. However, Integrated Coastal Zone Management should
be taken into consideration in planning for any developmental activities in
coastal areas.
There have been stress on the issues of
conservation of native and local livestock in the recent past, the important
ones being Garol sheep of Sundarbans, Swamp buffalo of Sundarbans, Nicobari
fowls of Andaman & Nicrobar Islands, Black Bengal goats, Gir cattle, etc.
Billy, the goat breed resident of Barren Island in the Andamans (Barren Island
is home to the only active volcano in the country) has survived the valcano’s
eruption by migrating to the unaffected side of the island, feeding on its
sparse foliage, and surviving on seawater.
Generically, Billy is a feral goat-nomadic, untamed – in barren Barren
island. Few other animals have been known to withstand the vagaries of such a
harsh environment. Feral goats like Billy could be bred in “Zero management
farms” that can provide enormous quantities of mutton at next to no cost. For
one, the feral goat could be the answer to the livestock problems of
drought-affected regions, where fresh water is in short supply. Secondly,
research work on its kidney, which has adapted to seawater could yield rich
results (Drinking saline water can kill a human being in a matter of days). But
how did Billy get on Barren Island in the first place? But if Billy is such a
hot property, then why isn’t he world-famous yet? It will be quite some time
before Billy finds his way to fame, which is bound to land it up on elite
dinner tables.
In addition, livestock and poultry strains of
economic importance in different coastal areas should be identified and
conserved. For example, improved strains
of birds as backyard poultry units in tribal areas may be identified and
conserved. Appropriate genetic engineering and other biotechnological tools should
be utilized for developing improved breeds with specific desired characters for
the region. Technological improvement and popularization of duck rearing should
be given importance (Sen et al.,
2010).
Ecology
Forest resources
The present status of forest areas in the East and West coastal
belts constitute only about 18.7 and 29.0 percent, respectively of the total
geographical area of the country. The forest coverage in the A&N Islands,
however, is as high as nearly 88 percent of its total land area. Mangroves
growing under natural conditions along the coastal shoreline occupy nearly 0.4
million hectare (6460 km2) in the country comprising about 7 percent
of the world’s mangroves. Reefs are not abundant along the Indian coast occupying
only 7 percent to a coastal length of 420 km. Seagrasses, on other hand,
intermingle with both mangrove and reef communities at their respective seaward
and landward boundaries. In the Indian coastline the seagrasses were found to
be efficient in cleansing the water contaminated by oil spills and effluent
discharge to the extent of 20-100 percent in the Gulf of Mannar and Palk Bay
(Sen et al., 2000).
In spite of the fact that mangroves have a very useful role to maintain
the level of CO2 and other toxic gases in the atmosphere they also
remove toxic materials and excess nutrients from estuarine waters. In addition, sediment and other inert
suspended materials are mechanically and chemically removed from the water and
deposited in the marsh or swamp, reducing the sedimentation of navigation
channels and shellfish beds. The vegetation also slows the surge of floodwaters
and may help to reduce the severity of flooding. Vegetation serves to stabilize
estuarine shorelines and prevent erosion; for example, mangrove trees not only
preserve shorelines, but actually can extend the land’s edge by trapping
sediments and building seaward. Thus, mangroves support unique coastal ecosystems
especially on their intricate root systems. In areas where roots are
permanently submerged, they further play a role of hosting a wide variety of
organisms, including algae,
barnacles, oysters, sponges, and bryozoans, which all require a
hard substratum for anchoring while they filter feed. Shrimps
and mud lobsters use the muddy bottom
as their home. Mangroves thus form a vital food web link among various aquatic
and wild animal species. It is irony that, globally, about 50 percent, and in
some countries, as high as 85 percent, of mangrove forests have been lost in
the last 50 years mostly due to human interventions. An estimated 35% of
mangroves have been removed due to shrimp and fish aquaculture, deforestation,
and freshwater diversion. Hydrology of the rivers in the coastal ecosystem or
any other human intervention including soil and water management practices in
the coastal plain that might threaten the natural forest environment should be
highly unwarranted.
Sedimentation
and Erosion
The dynamics of alluvial
landscapes and natural sedimentation patterns that determine the nutrient and
energy flows in coastal areas are increasingly being modified by human
activities, in particular those that affect water flows (dams, increased water
extraction, deviation of rivers) and erosion, and especially due to
deforestation. This prevents or slows down vertical accretion, thus aggravating
salt water intrusion and impairing drainage conditions in riverine, delta or
estuarine areas. It reduces or blocks sediment supply to the coast itself,
which may give rise to the retreat of the coastline through wave erosion. Beach
erosion is a growing problem and affects tourism revenue, especially in island
nations. In the Caribbean, as much as 70 percent of beaches studied over a
ten-year period were eroded.
Eutrophication,
Hypoxia, Dead Zones and Nutrient Cycle
The urban developments are
taking up fertile agricultural land and leading to pollution of rivers,
estuaries and seas by sewage as well as industrial and agricultural effluents.
In turn, this is posing a threat to coastal ecosystems, their biological
diversity, environmental regulatory functions and role in generating employment
and food. Overuse of fertilizer can result in
eutrophication, and in extreme cases, the creation of ‘dead zones’. Dead zones occur when excess nutrients—usually nitrogen and
phosphorus—from agriculture or the burning of fossil fuels seep into the water
system and fertilize blooms of algae along the coast. In dead zones, huge growth of algae reduces oxygen in the
water to levels so low that nothing can live. There
are now more than 400 known dead zones in coastal waters worldwide, compared to
305 in the 1990s, according to a study undertaken by the Virginia Institute of
Marine Science. Those numbers were up from 162 in the 1980s, 87 in the 1970s,
and 49 in the 1960s. In the 1910s, only four dead zones were identified
(Minard, 2008). Hypoxia in the Northern Gulf of Mexico, commonly named
as the 'Gulf Dead Zone', has doubled in size since researchers first mapped it
in 1985, leading to very large depletions of marine life in the affected
regions (Portier, 2003).
The World Resources Institute (2006) reported that driven by a
massive increase in the use of fertilizer, the burning of fossil fuels, and a
surge in land clearing and deforestation, the amount of nitrogen available for
uptake at any given time has more than doubled since the 1940s. In other words,
human activities now contribute more to the global supply of fixed nitrogen
each year than natural processes do, with human-generated nitrogen totaling
about 210 million metric tons per year, while natural processes contribute
about 140 million metric tons. This influx of extra nitrogen has caused serious
distortions of the natural nutrient cycle. In some parts of northern Europe,
for example, forests are receiving 10 times the natural levels of nitrogen from
airborne deposition, while coastal rivers in the Northeastern United States and
Northern Europe are receiving as much as 20 times the natural amount from both
agricultural and airborne sources (Coastal Wiki,
2008).
Climate Change and its impact
Destruction of habitats in coastal ecosystem is
caused by natural disasters,
such as cyclones, hurricanes, typhoons, volcanism, earthquakes and tsunamis,
frequency of which is increasing at almost exponential rate with time (Sen,
2010), causing colossal losses worldwide. Each year an estimated 46
million people risk flooding from storm surges.
It has also been
predicted (IPCC, 2007) that increase in sea surface temperature of about 1-3°C might
result in more frequent coral bleaching events and widespread mortality unless
there is thermal adaptation or acclimatization by corals.
The impacts on sea
level rise are expected to be more local than global. The relative change of
sea and land is the main factor. Many cities, for instance, even suffer land
subsidence as a result of ground water withdrawal. This may be compounded with
sea level rise, especially since rates of subsidence may exceed the rate of sea
level rise between now and 2100. In India, potential
impacts on 1 m sea level rise might lead to inundation of 5,763 km2
of land including Ganges-Brahmaputra delta facing flood
risks from both large rivers and ocean storms. Apart from the
inundation of low lying coastal areas, including parts of many major cities, more significant are
the direct loss of land caused by the sea rising and the associated indirect
factors, including erosion patterns and damage to coastal infrastructure,
salinization of wells, sub-optimal functioning of the sewage system of coastal
cities (with resulting health impacts), loss of littoral ecosystems and loss of
biotic resources. Climate change thus affects wide
array of sensitive sectors like agriculture, forestry and fishery and thereby
the livelihoods of millions of coastal communities.
Regarding
climate change policies, it is mentioned that the coverage of GoI on coastal
protection has been limited to soft activities which include high resolution
modelling, development of salt tolerant crops, timely forecasting and warning
of flood and cyclones occurrences, and enhanced plantation and regeneration of
mangroves and coastal forests. Unlike Bangladesh sharing similar coastal
ecologies in as far as Sundarbans is concerned, ‘adaptation’ to the miseries
due to the weather extremes has been little emphasized in the policy of India.
‘Mitigation’ policies are also widely different in the two countries. Even
policies and strategies to tackle loss of marine and coastal eco-region are
widely different. India however gives considerable importance to mitigating
greenhouse gas emission through expansion of renewable wastes and
afforestation. Making note of such wide
variation in the country-wise policies on key issues on climate change in
Sundarbans it is strongly advocated, to start with, undertake integration of the policies of the
two countries, and possibly Nepal also, all sharing the GBM basin, under the
aegis of SAARC, to address key concerns and vulnerabilities, and discuss all
related issues with open mind having full regards to geo-political sovereignty
of the countries.
Lowlying coastal soils:
The probable effects on soil characteristics of a gradual eustatic rise in sea
level will vary from place to place depending on a number of local and external
factors, and interactions between them (Bramner and Brinkman, 1990).
In principle, a rising sea level would tend to erode and move back existing
coastlines. However, the extent to which this actually happens will depend on
the elevation, the resistance of local coastal materials, the degree to which
they are defended by sediments provided by river flow or longshore drift, the
strength of longshore currents and storm waves, and on human interventions
which might prevent or accelerate erosion.
Sediment supply and deltaic
aggradation: In major deltas, such as
those of the Ganges-Brahmaputra and the major Chinese rivers, sediment supplies
delivered to the estuary will generally be sufficient to offset the effects of
a rising sea level, but on the other hand it would impair the drainage system
as well.
Tidal flooding: In
coastal lowlands which are insufficiently defended by sediment supply or
embankments, tidal flooding by saline water will tend to penetrate further
inland than at present for the lack of adequate drainage in case of the former,
extending the area of perennially or seasonally saline soils. Where Rhizophora
mangrove or Phragmites vegetation invades the area, would over
several decades lead to the formation of potential acid sulphate soils.
Impedance of drainage from the land by a higher sea level and by the
correspondingly higher levels of adjoining estuarine rivers and their levees
will also extend the area of perennially or seasonally reduced soils and
increase normal inundation depths and durations in river and estuary basins and
on levee backslopes. In sites which become perennially wet, soil organic matter
contents will tend to increase, resulting eventually in peat formation. On the
other hand, where coastal erosion removes an existing barrier of mineral soils
or mangrove forest, higher storm surges associated with a rising sea level
could allow seawater to destroy existing coastal eustatic peat swamps, which
might eventually be replaced by freshwater or saltwater lagoons.
Subsidence of land:
The probable response of lowlying coastal areas to a rise in sea level can be
estimated in more detail on the basis of the geological and historical evidence
of changes that occurred during past periods when sea level was rising
eustatically or in response to tectonic or isostatic movements, e.g. around the
Southern North Sea; in the Nile delta; on the coastal plain of the Guyanas; in
the Musi delta of Sumatera. Major shifting of the river course of the Ganga-Brahmaputra
river system and a large number of their tributaries took place due to
neo-tectonic movement in Bengal basin during 16th to 18th century, which
eventually led to massive change of the hydro-geological properties in lower
Ganges delta affecting livelihood in both India (related areas) and Bangladesh.
Contemporary evidence is also available in areas where land levels have
subsided as a result of recent abstraction of water, natural gas or oil from
sediments underlying coastal lowlands. Further studies of such contemporary and
palaeo-environments are needed together with location specific studies in order
to better understand the change processes, identify appropriate responses and
assess their technical, ecological and socio-economic implications.
Erosion: It is an
important area influenced by the climate change with rising temperatures
leading to rise in the sea’s water mass. In India the mainland consists of 43 %
sandy beaches, 11 % rocky coast with cliffs, and 46 % mud flats and marshy
coast (SAARC Disaster Management Centre, 2009). The damages caused by sea
erosion in different coastal states in India alone show a staggering annual
loss of Rs. 368.387 crores. Various preventive and mitigation measures have
been suggested and being adopted, which are mainly of two types: (i) Structural
measures and (ii) Non-structural/ soft measures.
Agro-ecotourism
In Kerala, Goa and adjoining areas, spice gardens
are given another dimension in terms of their role in tourism industry.
“Agro-Ecotourism” is the symbiotic association of farming sector and tourism
industry. Spice crops are the destinations of Agro-ecotourism for Western or European
tourists in Goa. Tropical spice crops as kokum, black pepper, clove, nutmeg,
cinnamon, cardamom, all spice, vanilla, etc coupled with native fruit crops
like banana, jack fruit, bread fruit, mango, cashew, etc., are incorporated in
palm- based farming systems or agro-forestry systems with specific orientation
towards Agro-ecotourism gardens. It is strongly suggested for
Sundarbans, based on the lessons learnt, to explore newer development options
for livelihood security in non-farm sector through ecotourism with mangrove
destinations.
I am
really appreciative of large turn-out of delegates including senior dignitaries
and guests from different parts of the country to participate in the symposium.
I thank through them their authorities for nominating them. Let this symposium
be the landmark for drawing future road map for coastal eco-regions of the
country. I wish all of you a happy stay and safe return back home at the end of
the deliberations. Finally, I owe deeply
to the dedicated support of the esteemed VC of Dr. B.S.K.K.V., the two
collaborating societies – Dapoli chapter of ISCAR and ISASaT - for making this
event a grand success. My heart goes out to thank my colleagues at the ISCAR
headquarters at Canning Town for their untiring efforts and meticulous support.
Lastly, I will fail in my duties if don’t express my indebtedness to the
immediate past VC of this great university for being instrumental to arrange
this programme, give it an excellent shape through his dynamic leadership, and
lending all necessary support, be it logistic or otherwise. Wish you all
meaningful deliberations.
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