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Study on the Status of Corals in Palk Bay, Southeast Coast of India During 2007-2013

Study on the Status of Corals in Palk Bay, Southeast Coast of India During 2007-2013

Indian Journal of Geo-Marine Sciences Vol. 44(9), September 2015, pp. 1449-1462

Study on the status of in Palk Bay, Southeast coast of during 2007-2013

*J.K. Patterson Edward, G. Mathews, K. Diraviya Raj & S. Rajesh Suganthi Devadason Marine Research Institute44-Beach Road, Tuticorin – 628 001, India

*[E-mail: [email protected]]

Received 12 November 2013; revised 25 February 2014

Present study consists the status of corals in Palk Bay, conducted during 2007-2013. Corals are distributed in four sites (Mandapam north, Pamban, and Olakuda) in Southern Palk Bay. The overall live cover was 30.78, 29.64 and 28.24% respectively during July 2007, September 2009 and April 2013. A sharp decrease in the live coral cover was observed in Mandapam north from 34.18 to 22.62% during the study period and an increase of algae from 14.88 to 31.52% was also recorded. The overall disease prevalence increased from 15.28% to 17.32% between 2009 and 2013. A complete stretch of cytherea in Mandapam north was dead because of the and the area is now dominated by macro algae. The other anthropogenic factors including destructive fishing practices, cultivation of exotic seaweed, Kappaphycus alvarezii, and elevated temperature pose threat to corals in Palk bay.

[Keywords: Palk Bay, coral status, disease, , management]

Introduction enhanced disturbances. Coral reefs have declined over Coral ecosystems constitute one of the most the course of human history, culminating in the valuable natural resources to humanity. They are most dramatic increase in coral mortality and reef productive, complex and diverse1-4 and can be degradation of the past 20-50 years10. The causes of justifiably compared to tropical rainforests5-6. These this degradation are a complex mixture of direct tropical marine communities occupy less than 1% of human-imposed and climate-related stresses, and the ocean floor, but are inhabited by at least 25% of include factors such as outbreaks of coral diseases. all marine . The intrinsic value of coral reefs is Wilkinson, (2008)11 reported that about 19% of the manifold and not easy to quantify. Apart from direct world’s coral reefs have already been lost and a commercial value deriving from the harvesting of further 35% are seriously threatened. As a result, one- marine organisms such as fishes, molluscs, third of all reef building corals are considered to be at cephalopods, echinoderms and the collection of risk of extinction12. ornamental species for the aquarium and curio trade, there are other, secondary values. Reefs serve as In the Indian subcontinent, the reefs are distributed major tourist attractions, carbon sinks, shoreline along the east and west coasts at restricted places and 13 protectors, source of building material and a range of all the major reef types are present . Coral reefs in other commodities and hold a great research India mainly occur in Gulf of Mannar and Palk Bay, potential2, 7-8. Lakshadweep, Andaman & Nicobar Islands, and Gulf of Kutch and all these major reefs are under natural Because coral reefs occur near the junction of land, and anthropogenic threats. Majority of the corals in sea, and atmosphere, their natural habitats experience the Palk Bay region are distributed on the southern i.e. both the marine and terrestrial results of any climatic northern side of the Island to change and are vulnerable to human activities. A wide Vedhaalai, covering a distance of about 25 km variety of environmental factors that are not directly coastline. The corals in Palk Bay runs parallel to the related to changes in the climate system have the land (east to west direction) between longitudes 79° potential to stress coral reefs. Reef communities have 17' E and 79° 8'E at the latitude 9° 17'N. Dr. C.S. been described as “disturbance-adapted” ecosystems9, Gopinatha Pillai, an internationally renowned coral but that adaptation is to natural rather than human- taxonomist, who has carried out detailed study during 1969, classified the reef area of Palk Bay into five 1450 INDIAN J. MAR. SCI., VOL. 44, NO. 9 SEPTEMBE 2015

zones - shore, lagoon, shoreward slope, reef crest and identified (Fig.1). The details of study areas in South seaward slope. Shore of the reef is mostly sandy with Palk Bay are given in the Table 1. dead pieces of corals, except at the extreme eastern and near the Pamban Bridge where one can see traces 14 Initial assessment on corals to collect baseline of sandstones. Pillai (1969) has made his information was done during July 2007. Throughout observations as provided below: Poor representation the assessment, scuba diving/snorkeling was used to of corals on the reef and widely spaced nature of the collect data. Second assessment was done in the same colonies indicate that the reef in consideration is not areas during September 2009 and the recent an actively growing one in Palk Bay. Widely spaced assessment was done during April 2013. Line and poor growth of corals at Palk Bay indicates that Intercept Transect (LIT) method following English et the existing ecological factors are not very congenial al. (1997)20 was used to assess the sessile benthic for a luxuriant growth of corals. Shore as well as the community of the reef and to assess the percentage of lagoon bottom in the Palk Bay being sandy, a large live coral cover. The number of transects ranged quantity of silt is stirred up during the period of north- between 20 and 85 according to the size of the reef. east monsoon, the wind at this period mostly crossing Each change of life form categories along the tape the shore in a north-east direction. The stirred up sand measures was recorded on data sheets (Table 2). and silt get suspended and the lagoon waters look Percentage cover of each live form category was muddy during this period. Effect of silt during north- calculated following the method of English et al. east monsoon is a marked degree here, which prevents (1997)20. Assessment on coral diseases was done a healthy growth of corals. Living colonies show a during September 2009 and April 2013 since the large number of buds at the onset of calm period 15 prevalence of diseases was witnessed significantly. To indicating a state of active growth. Pillai (1971) assess the coral diseases, diseased coral colony and recorded 66 species of corals belonging to 23 genera total number of colonies were recorded. Disease in Palk Bay which is far less than 117 coral species in prevalence was calculated by using the formula, Gulf of Mannar.

In the Palk Bay, corals are being disturbed by Number of diseased colonies human impacts through oil pollution, waste discharge Disease prevalence = ……………………………… X 100 from processing units and discharge of domestic Total number of colonies household wastes from the nearby Mandapam town16. Coral diseases also have been related to the disturbed health of Palk Bay reef17-18. Present bench mark data on the status of corals in Palk Bay was collected and regularly updated with the intention to provide an understanding on the state of coral status and health and the stress factors, so that appropriate management strategies could be adopted in the area where now no legal conservation system is in existence.

Materials and Methods Palk Bay is shallow basin with an average depth of 9 meters with many muddy bottom at inshore regions. Reefs occur at a depth between 0.5 and 5 m in South Pak Bay, starting 100 m from shore up to 5 m depth and abundance between 0.5 and 2.0 m. Preliminary assessment was done using manta tow technique to Fig. 1 - Map showing the study areas (Mandapam North, Pamban, assess broad changes in benthic communities19 during Thangachimadam and Olakuda) in Palk Bay July 2007. Four distinct coral areas (Mandapam

North, Pamban, Thangachimadam and Olakuda) were

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Table 1: Details of study areas in Palk bay Sites GPS mark Depth range Mandapam North 090 17.560'N 0790 10.729'E 1.0 to 5 m 0 0 Pamban 09 17.627'N 079 08.284'E 0.5 to 4 m Thangachimadam 090 18.326'N 0790 16.234'E 0.5 to 3.5 m Olakuda 090 18.366'N 0790 19.395'E 0.5 to 3 m Table 2: Life form categories and codes (English et al., 1997) Categories Code Notes / Remarks

Dead Coral DC recently dead, white to dirty white Dead Coral with Algae DCA this coral is standing, skeletal structure can still be seen Acropora Branching ACB at least 2° branching Encrusting ACE usually the base-plate of immature Acropora forms Sub massive ACS robust with knob or wedge-like form Digitate ACD no least 2° branching, typically includes Tabular ACT horizontal flattened plates Non – Acropora Branching CB at least 2° branching Encrusting CE major portion attached to substratum as a laminar plate Foliose CF Coral attached at one or more points, leaf-like, or plate-like Submassive CS tends to form small columns, knobs, or wedges Mushroom CMR solitary, free-living corals of the Fungia Heliopora CHL Millepora CME CTU organ-pipe coral Other Fauna: Soft Coral SC soft bodied coral Sponge SP Zooanthids ZO examples are Others OT Ascidians, anemones, gorgonians, giant clams etc. Algae Algal Assemblage AA consists of more than one species CA Halimeda HA Macroalgae MA weedy/fleshy browns, reds, etc. TA lush filamentous algae, often found inside damselfish Turf Algae territories Abiotic Sand S Rubble R unconsolidated coral fragments Silt SI Water WA fissures deeper than 50 cm Rock RCK Other DDD Missing data

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Results Goniastrea retiformis and soft corals like The overall percentage of live coral cover in Palk Sacrophyton sp., Sinularia sp., Cladiella sp. and Bay is ‘fair’. In July 2007, the live coral cover was Lobophytum sp. The details of the benthic 30.78%; however a slight decline was recorded community structure and coral life form categories during September 2009 to 29.64% and a further in Pamban are given in the figures 6 and 7. decline during April 2013 to 28.24%. A decrease of 2.54% in live coral cover was noticed between July Table 3: Coral area cover (km2) details in Palk Bay 2007 and April 2013. Interestingly, an increase of 4.1% of algae was recorded in almost six years Mandapam Pamban Thangachi Olakuda which has increased from 16.18 to 20.28%. DCA North madam and abiotic factors were consistent through the 2007 4.35 3.77 1.89 3.33 study period. The details of the overall benthic community structure are given in the figure 2 and 2009 3.24 3.56 2.15 3.75 the changes in the live coral cover in each site over the years are given in the figure 3. Total coral area 2013 2.15 3.62 2.05 3.52 cover (Km2) in the four areas in Palk bay was 13.34 Km2 in 2007 and it reduced to 11.34 Km2 in 2013 and the details are given in Table 3.

In Mandapam North, live coral cover has decreased significantly from 34.18% in 2007 to 22.62% in 2013. The percentage of algae increased extensively from 14.88% in 2007 to 31.52% in 2013. The percentage of DCA was 23.79 and 21% respectively in 2007 and 2013 the abiotic factors were 21.6 and 18.75% respectively. Among the coral life form categories massive corals were dominant with 21.16 and 18.74% respectively. Acropora table corals (Acropora cytherea) decreased drastically from 7.92% during 2007 to Fig. 2 - Overall benthic community structure in Palk Bay 0.78% during 2013. Other significant life form categories were ACB, ACD and CS. Dominant coral species recorded were Porites solida, P.lichen, Favia pallida, Favites sp. and Goniastrea retiformis. The details of the benthic community structure and coral life form categories in Mandapam north are given in the figures 4 and 5. In Pamban, not much change was recorded in the live coral cover with 35.26 and 34.79% respectively during 2007 and 2013. All the other benthic categories also did not show much deviation. DCA was around 20%; algae were around 15%; abiotic factors were around 19% and others were around 9%. Among the coral life form categories CM was Fig. 3 - Deviations in the live coral cover at each site dominant with 28.34 and 29.34% respectively in 2007 and 2013 distantly followed by CS with 3.05 In Thangachimadam, no significant change was and 3.28% respectively. Dominant coral species recorded in the live coral cover between 2007 and recorded were hard corals like Acropora cytherea, 2013 (24.1 and 24.43%). All the other benthic Porites solida, Symphyllia radians, Favia pallida, categories also did not show much deviation from Favites sp., Platygyra sp., Leptoria sp. and 2007 through 2013. DCA was around 28%; algae PATTERSON et al.: STUDY ON THE STATUS OF CORALS IN PALK BAY 1453

were around 17%; abiotic factors were around 26% and others were around 4%. Among the coral life form categories CM was dominant with 17.45% in 2007 and 18.65% in 2013 distantly followed by CS and ACT. Dominantly recorded coral species were hard corals like Acropora cytherea, Porites solida, Symphyllia radians, Favites sp. and Platygyra sp. and soft corals like Sacrophyton sp., Sinularia sp., Cladiella sp. and Lobophytum sp. The details of the benthic community structure and coral life form categories in Thangachimadam are given in the Fig. 7 - Coral life form categories in Pamban figures 8 and 9.

Fig. 8 - Benthic community structure in Thangachimadam Fig. 4 - Benthic community structure in Mandapam North

Fig. 5 - Coral life form categories in Mandapam North Fig. 9 - Coral life form categories in Thangachimadam

Fig. 6 - Benthic community structure in Pamban Fig. 10 - Benthic community structure in Olakuda 1454 INDIAN J. MAR. SCI., VOL. 44, NO. 9 SEPTEMBE 2015

40 35 2007 30 2009 25 2013 20

r c e n t a g e 15 P e 10 5 0 Live coral Bleached Live coral Bleached Live coral Bleached Live coral Bleached corals corals corals corals

Mandapam North Pamban Thangachimadam Olakuda

Fig. 11 - Coral life form categories in Olakuda Fig. 15 - Percentage of in Palk Bay during 2007, 2009 and 2013

In Olakuda, no significant change was found in the live coral cover with 29.56% in 2007 and 31.1% in 2013. All the other benthic categories also did not show much deviation from 2007 through 2013. DCA was around 26%; algae were around 17%; abiotic factors were around 21.9% and others were around 4%. Among the coral life form categories, CM was dominant with 21.44% in 2007 and 24.74% in 2013 distantly followed by CS and ACT. Fig. 12 - Disease prevalence in Palk Bay Dominantly recorded coral species were hard corals like Acropora cytherea, Porites solida, Symphyllia radians, Favites sp. and Platygyra sp. and soft corals like Sacrophyton sp., Sinularia sp., Cladiella sp. and Lobophytum sp. The details of the benthic community structure and coral life form categories in Olakuda are given in the figures 10 and 11.

The overall disease prevalence in Palk Bay in 2009 was 15.28% and it increased to 17.32% in 2013. In general, the contribution of black band disease was high both in 2009 (47%) and 2013 (57%) followed by (BBD) with 22 and 18% respectively. Acropora spp. was highly Fig. 13 - Prevalence of each disease type in Palk Bay affected with 8.5% in 2009 and it increased to 16.8% in 2013 followed by Porites spp. with 5.2% and 5.8% respectively. Disease prevalence was very high in Mandapam north (35.2% in 2009 and 45.36% in 2013). In Pamban, Thangachimadam and Olakuda areas, the incidence of diseases did not vary significantly and it was 8.6 to 8.3%, 7.7 to 7.2% and 9.6 to 8.4% respectively from September 2009 to April 2013. In Mandapam North, a complete stretch of Acropora cytherea is dead due to BBD and is currently overgrown by macro algae. Macro algal species, Padina sp., Turbinaria sp., Fig. 14 - Prevalence of diseases in each genus in Palk Bay Caulerpa sp. and Saragassum sp. are found PATTERSON et al.: STUDY ON THE STATUS OF CORALS IN PALK BAY 1455

abundant over the dead coral colonies. Details on and figure 20 shows impact of exotic seaweed, the disease prevalence in Palk Bay are given in the Kappaphycus alvarezii cultivation on corals. figures 12 to 14. Discussion Though fishing is practiced in the coral areas in the Palk Bay using various gears, the trap fishing The importance of ecosystems may be causes the severe destruction to healthy coral seen in their numerous ecological, aesthetic, colonies. The setting up and retrieving of traps in economic, and cultural functions. Ability of coral the coral areas damage corals as well as over reef ecosystems to exist in balanced harmony with exploitation of herbivorous fishes through traps lead other naturally occurring competing/limiting into ecological imbalance as the macroalgae physicochemical and biological agents has been dominate in the live coral area. Cultivation of exotic severely challenged in the last several decades by seaweed Kappaphycus alvarezii in the South Pak the dramatically increased negative and synergistic Bay near coral areas pose threat in the form of impacts from poorly managed anthropogenic obstruction of adequate sunlight and also damage of activities. For many years, increasing degradation of corals. Seaweed cultivation areas become turbid. coral reefs has led to reduction in , productivity and other utilitarian functions of reefs The corals in Palk Bay are located in depth such as provision of wave barriers for shorelines22. between 0.5m and 5 m and hence easily prone to Because reefs are long lasting geological structures elevated sea surface temperature and annual with great habitat complexity, loss of the three bleaching event. During summer, the temperature dimensional reef structure which comes from varied level ranges between 31 and 33°C in reef areas. In and profuse coral growth leads to a loss of diversity 2007, The percentage of coral bleaching ranged of many other reef dwelling biotic groups as well23. between 18.47 and 26.35% with the highest in As pressures on coral reef resources have increased Mandapam north and lowest in Thangachimadam; as a result of demographic changes so has In 2009, the bleaching was between 16.74 and degradation of the support systems (coral reef 23.15% with highest in Pamban and lowest in ecosystems) which produce those resources. Thanchimadam; and in 2013, the percentage of Subsequent reef degradation can potentially have bleaching ranged between 6.28 and 9.78% with strong secondary impacts on the livelihoods of highest in Olakuda and lowest in Mandapam north coastal populations through adverse impact on for (Fig. 15). Massive corals especially Porites sp. were example fish stocks and tourism24. The study on the the first to be affected followed by the others. status of corals in Palk Bay reveals that they are Recovery starts normally from July when the ‘fair’ in abundance and help hundreds of artisanal temperature level falls below 30°C and no mortality fishers depending on the associated fishery was recorded in Palk Bay during 2007, 2009 and resources. However, in Mandapam north area, an 2013 due to bleaching. In 2010, there was coral alarming increase of coral disease prevalence and mortality due elevated temperature in nearby Gulf consequent mortality has been noticed during the of Mannar, but no data was collected in Palk Bay six year study period which needs a serious during this period. Higher temperature is managerial attention. contributing also to the spreading rate of BBD and killed a complete stretch of Acropora cytherea. Reports of disease like syndromes in reef building corals have increased since the first report The underwater photographs of Palk Bay corals by Antonious, (1973)25 and the rate of increase has are given in the figures 16 to 20. Figure 16 shows gone high globally in the recent past26-28. Recent the healthy coral species recorded in Palk Bay in studies, indicate an escalating abundance and April 2013. Figure 17 shows the healthy and BBD prevalence of coral diseases throughout the Pacific affected Acropora cythera in Mandapam North and and suggest diseases may play a more important subsequent algal dominance during 2007-2013. role in structuring Indo- communities Figure 18 shows the impact of trap fishing on than previously thought29. In the present study, a corals. Figure 19 shows coral bleaching in Palk Bay sharp decrease in the live coral cover was observed 1456 INDIAN J. MAR. SCI., VOL. 44, NO. 9 SEPTEMBE 2015

in Mandapam north in 4 years period because of the sedimentation and pollution. Apart from human mortality caused by black band disease. Incidence disturbances, Palk Bay reef is highly affected by of disease was 35.2% during September 2009 in sunlight during low tide for a very long period, Mandapam north and it increased to 45.36% during which leads to mortality and radiation April 2013 while the incidence of diseases in other infection as a consequence the reef crest area are areas was between 7 to 9% and did not vary densely populated by algal groups43. During the significantly. Loya et al., (2001)30 observed that present study period, the varied percentage of coral disease can cause significant changes in coral bleaching was observed with minimal bleaching reproduction and growth rates, community intensity in 2013. It is also noted that the bleached structure, species diversity, and abundance of reef- corals started recovering from July once associated organisms. temperatures level falls. In 2010, there is no data collected in Palk Bay and it was reported in nearby Global reef decline can sometimes be attributed Gulf of Mannar that elevated temperatures (32.2 to to proximal causes like destructive fishing and 33.20C) persisted for four months (April to July) in pollution, but we do not have a good understanding 2010. During the previous years, periods of elevated of how population, community and ecosystem temperature lasted only two months (April to May). structure and function differ in degraded from un- An estimated 9.97±2.27% (mean ± SD) of coral degraded reefs31. The percentage of algae increased colonies bleached in 2010, with 50% mortality drastically from 14.88% in 2007 to 31.52% in April among bleached colonies. Mortality was recorded in 2013 in Mandapam north. Degraded reefs are often Pocilopora damicornis, Acropora formosa, A. characterized by high cover of fleshy algae and high intermedia, A. nobilis, A. cytherea, Montipora microbial densities, complemented by low digitata, Montipora foliosa, Favia sp. and abundance of coral and coral recruits32. Coral- Echinopora sp. and branching corals were mostly macroalgal shifts have been reported from the dead44. This BBD affected area in Manapam north Caribbean33-34, eastern Africa35-36, Australia37 and is very shallow (0.5 to 1m) and prone to higher the eastern Pacific38-39. water temperature which could possibly be the reason for complete mortality of Acropora cytherea. The term coral-algal phase shift refers to the phenomenon of coral reefs shifting to unusually low Land based pollution and the pollution from levels of coral cover associated with persistent Mandapam fishing trawlers also could be the reason states of high cover of fleshy macro algae It is behind the increased disease incidence. Higher level widely recognized that the persistence of these shift of nutrients coupled with higher sea surface has increased in the past few decades40. Such a temperature might have increased the rate of phase shift is being witnessed in Mandapam north progression of BBD and killed Acropora cytherea where a complete stretch of Acropora cytherea has completely17. The infected coral colonies been dead and the area is now occupied by macro immediately dominated by the macro algae algae. There is a rising concern over the ability of hindering the corals from recovery. Macro algal diseases to cause species shifts, restructure coral species, Padina sp., Turbinaria sp., Caulerpa sp. populations, and cause a decrease in coral species and Saragassum sp. were found abundantly over the diversity41. For instance, it has been estimated that infected coral colonies. Trap fishing is also the disease, white pox, has been responsible for contributing not only to the damage of corals, but reducing the population of the , also in the proliferation of algae as herbivore reef Acropora palmata, by up to 87% in the Florida fishes especially parrot fishes are over exploited, Keys between 1996 and 200242. resulting ecological imbalance due to depletion of algal feeders which makes the macro algae to Coral colonies affected by black band disease proliferate freely. were reported to be infected with cyanobacterial species Phormidium sp. and Pseudomonas sp. Despite the fact that corals in Mandapam north which might be the causative agents17. Palk Bay are under stress, it is also noted that other areas reefs are influenced by destructive fishing activities, namely Pamban, Thangachimadam and Olakuda are PATTERSON et al.: STUDY ON THE STATUS OF CORALS IN PALK BAY 1457

not significantly affected by coral diseases and area in Palk Bay is not having any legal consequent mortality. A mere decrease (2.54%) in conservation status. Therefore appropriate and the live coral cover and 4.1% increase in the algal careful conservation and management strategies cover were recorded in Palk Bay throughout the need to be developed to protect the corals in Palk study period. However, it is essential to take up Bay, including consideration of community reserve. necessary steps to check the proliferation of the This could be made possible through awareness diseases and algae. Though we cannot do much on building among the local community and also the elevated temperature, other anthropogenic actively involving them in the management stresses to corals could be reduced. In particular, the practices. The management strategy should be impact due to the cultivation of exotic seaweed, bottom up process, so that the support and Kappaphycus alvarezii could be reduced if involvement of the community is ensured. Manual appropriate steps are taken strictly by following the removal of macro algae can be done to expose the G.O. issued by the Government of in dead corals for the new recruits to attach, however it December 2005 [G.O. Ms. No.229, E & F (EC.3) requires regular monitoring with considerable Department dated 20.12.2005]45 which states that K. budget allocation. Coral rehabilitation can be alvarezii can be cultivated by Self Help Groups considered to restore the degraded areas through (SHGs) in the seawaters North of Palk Bay and simple transplantation technique, but no South of Tuticorin coast. conservation intervention including rehabilitation would be successful without addressing the key Corals are protected species under Schedule - 1 issues in the Palk Bay. of the Wildlife Protection Act, 1972, but the coral

16a. Acropora cytherea 16b. Favites abdita

16c. Symphyllia radians 16d. Porites lutea 1458 INDIAN J. MAR. SCI., VOL. 44, NO. 9 SEPTEMBE 2015

16e. Soft coral, Sinularia sp. 16f. Soft coral, Sacrophyton sp.

Fig.16 - a-f: Underwater photographs of healthy coral species recorded in Palk Bay in April 2013

17a. Healthy Acropora cytherea in Mandapam North in 2007

17b. The Acropora cytherea affected by Black Band Disease in Mandapam North in 2009

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17c. BBD affected Acropora cytherea covered by macro algae in 2013 Fig.17 a-c - Underwater photographs of healthy and disease affected A. cytherea in Mandapam North and subsequent algal dominance

18a. Fish traps set near massive corals in Palk Bay

18b. Macro algal dominance on live corals due to over exploitation of herbivorous fishes by fish traps Fig.18 a-b: Impact of trap fishing on corals in Palk Bay

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Fig.19 - Bleached massive corals in Palk Bay in April 2013

20a. Cultivation of exotic seaweed (K. alvarezii) in coral sites using rafts obstructs sunlight

20b. The K. alvarezii cultivation rafts and other materials causing damage to corals Fig.20 a-b - Impact of exotic seaweed, K. alvarezii cultivation on corals in Palk Bay

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