Climate change impacts on coastal resources and
dependent livelihood in Tamil Nadu, Southeastern India
Edward JK Patterson
Suganthi Devadason Marine Research Institute
Tuticorin – 628 001, Tamil Nadu, INDIA
www.sdmri.in
Tamil Nadu
• Coast - 1076 km
• 13 coastal districts
• > 800,000 active
fishermen
• Key coastal habitats like coral reefs, seagrass beds, mangroves, estuaries etc.
Map source: Ramesh et al., 2008 (modified)
Rivers
• There are 7 rivers
• Mostly seasonal now
• Several check dams
• Flow reduced
• Encroachment for aquaculture, construction etc.
• Sand mining
• Monsoon failure
• Loss of nutrient input in coastal systems
Human induced threats
• Population
• High dependency on fishery resources
• Destructive and over fishing (Trawling, Shore
seine, push net, traps etc.)
• Pollution - Domestic and Industrial
• Coral mining
• Mangrove deforestation
Others (incl. natural threats)
• Climate change
• Monsoon failure
• Increase of disease prevalence
• Cyclone, tsunami• Cyclone, tsunami
Gulf of Mannar - Case study 1 (Corals
reefs)
Reef status• Reef areas in Gulf of Mannar are formed around 21 islands at a depth
between 0.5 and 6 m.
• Total reef cover - 110 Sq.km; Present cover - 75-80 Sq.km
• Coral bleaching during 1998 – about 60%, over 90% recovery.
• Present live coral status - 40%
• Coral species – 117
• Associated flora and fauna - over 3900
Threats to coral reefs of Gulf of Mannar
• Coral mining
In 1970’s it was estimated that the exploitation of corals was about
60,000 cubic meters (about 25,000 metric tones) per annum.
In July 2001, the federal government included all corals under
schedule - I of Wildlife (Protection) Act, 1972.
• Fishing in reef areas (Inshore trawling, shore seine, traps)• Fishing in reef areas (Inshore trawling, shore seine, traps)
• Seaweed collection in reef areas
• Pollution - domestic
• Invasion of exotic seaweed
• Cyclone, tsunami
• Climate change
Coral status
• Regular Monitoring
since 2005
• Shows resilience
• Mortality (9.77%) in 2010
due to prolonged
elevated SST 0
10
20
30
40
50
60
2003- 2007 2008 2009 2010 2011C
ora
l cover
(mean%
± S
D)
elevated SST2003-
2005
2007 2008 2009 2010 2011C
ora
l cover
(mean%
± S
D)
22
25
28
31
34
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SS
T (
0C
)
2005
2006
2007
2008
2009
Average monthly SST values in the Gulf of Mannar during 2005 to 2009
31.6
32.6
31.6 31.6
33.5
32.1
31.6
32.9
31.7
31.0
32.5
31.331.0
32.5
31.3
30
30
31
31
32
32
33
33
34
34
Ap
r'0
5
Ma
y'0
5
Ju
n'0
5
Ap
r'0
6
Ma
y'0
6
Ju
n'0
6
Ap
r'0
7
Ma
y'0
7
Ju
n'0
7
Ap
r'0
8
Ma
y'0
8
Ju
n'0
8
Ap
r'0
9
Ma
y'0
9
Ju
n'0
9
2005 2006 2007 2008 2009
SST (
0C
)
Sea surface temperature (0 C) in summer (April, May and June) during 2005 to 2009
Coral bleaching
20
14.615.6
12.9
10.58.93
0
5
10
15
2005 2006 2007 2008 2009
Ble
achin
g (%
)
Temperature (0C) in Gulf of Mannar in 2010
28.6
29.6
31.5
32.2
33.2 33.132.8
31.2
29.4
28.3
27
28
29
30
31
32
33
34SST (
0C
)
25
26
Jan'10 Feb'10 Mar'10 Apr'10 May'10 Jun'10 Jul'10 Aug'10 Sep'10 Oct'10
Coral disease prevalence
• 6.7% in 2007 & 10.6%
in 2011
• Nine distinct types of
diseases
• disease susceptibility
increases when
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
Mandapam group Keezhakarai group Vembar group Tuticorin group
Perc
enta
ge %
increases when
elevated temp. 2007 2008 2009 2010 2011
Reef Associated Ornamental Fishes
• Over 70 reef associated fish species identified.
• Over 50% of the identified fishes are now become rare, threatened or highly
threatened – due to over exploitation and climate change effects
• Recent studies reveal that these fishes are seen in abundance in deeper
areas, where hard substrates (pars) with patch corals are available - 15 km
away from reefs with depth over 20m.
Algal Bloom in Reef Area
• October 2008 - algal bloom in reef area - Noctiluca scintillans.
• The oxygen level - 0.7 - 1.2 mg/l
• Over 5000 dead fishes and bivalves observed
• Several coral colonies were bleached.
• Seagrass beds was also affected.
27
27.528
28.5
29
29.530
30.5
Se
p'0
8
10
.10
.08
12
.10
.08
Se
p'0
8
10
.10
.08
12
.10
.08
Se
p'0
8
10
.10
.08
12
.10
.08
Se
p'0
8
10
.10
.08
12
.10
.08
Station-1 Station-2 Station-3 Station-4
Te
mp
era
ture
(0
C)
Surface
Bottom
Gulf of Mannar - Case study 2(Loss of Loss of LactariusLactarius lactariuslactarius fishery)fishery)
Fishery StatusFishing area /
village
1980-1990 Now
Tuticorin Over 10 tons per
day during peak
season
• Dissipating status
• 150 kg per day during peak season.
• Few catches are recorded from
Yeruvadi and Kanyakumari coast
• Fishermen pointed out that the
fishery has now changed towards
the Thalaimannar area of Sri Lankathe Thalaimannar area of Sri Lanka
Abundance of
False Trevally in
depths of 2 -5
fathoms
Fishermen need to travel 40-45 miles.
Fishing at depths over 20 fathoms.
Country crafts
had good catches
(300 – 500 kg)
Country crafts do not get Lactarius
Exclusive fishery
for False Trevally
No exclusive fishery - only by catch
Landing data of Lactarius in Tamil Nadu
1822
137313481400
1600
1800
2000
landin
gs in tons
640722
775 740840
938
537
679
537611
470
1028
1348
977
823
175
372
201
633714
234329
0
200
400
600
800
1000
1200
years from 1969 - 1993
landin
gs in tons
Reason for the loss of fishery
• Both nature and man are responsible.
• Lack of rain fall.
Out of 2 major rivers, Thamirparani flows throughout year,
but Vaipar has totally dried. Other two small rivers, Kallar
and Vembar also totally dried.
Lack of supply of food in the coastal waters, which is supported by • Lack of supply of food in the coastal waters, which is supported by continuous, unsustainable and repeated fishing in the same area..
• The effect of El-Nino during 1998 has caused a change in the climatic pattern - by an increase in temperature and decrease in rain fall.
• The climatic factor also supported by the destructive fishing practices.
Rainfall data
0
200
400
600
800
1000
1200
1994 1996 1998 2000 2002 2004
Years
Rain
fall in m
m
Average mean temperature
28.8
29
29.2
29.4
29.6
29.8
1994 1996 1998 2000 2002 2004
Years
Tem
pera
ture
in
Celc
ius
Effect on the socio-economics of dependent fishermen
• A decade ago
Fisherman with country craft able to earn Rs.600-700/day (peak season)
Fisherman with trawl boat – Rs.1000-1500/day
• Now
There is no exclusive fisheryThere is no exclusive fishery
Traditional fishermen are most affected
Summary• Tamil Nadu coast has productive key habitats which support good fishery.
• Traditional fishermen fully depend on fishery resources for livelihood.
• Human induced threats along with climate change impacts affect key habitats, associated fishery and livelihood of fishermen.
• The total cover and health of coral reefs, seagrass beds, mangroves and estuaries are reduced.
• Loss of fishery is noticed on various fish species - including Lactarius, Mackeral, Snapper, Barracuda, Pomfret, Grouper, Jacks, Lobster and Mud crab crab
• Migration, change of fishing practice, change of profession are seen among fishermen.
• The key habitats are managed under varied conservation status.
• Though the human influence is reduced within the Protected Areas, the climate change impacts cause series damage.
• Within the Protected Areas there are signs of resilience because of various management measures, including Coastal Ecosystem Rehabilitation activities to support the resilience.
• However, the combined effects of human influence and climate change hold the key.
•