Phenotypic Plasticity of Cycloseris Somervillei (Scleractinia: Fungiidae) in Andaman & Nicobar Islands

Indian Journal of Geo-Marine Sciences Vol. 42(5), September 2013, pp. 611-616

Phenotypic plasticity of Cycloseris somervillei (Scleractinia: Fungiidae) in Andaman & Nicobar Islands

Tamal mondal1, C. Raghunathan2, & K. Venkataraman3 1,2Zoological Survey of India, Andaman & Nicobar Regional Centre, National Coral Reef Research Institute, Port Blair 744 102, Andaman & Nicobar Islands, India 3Zoological Survey of India, Prani Vigyan Bhavan, M-Block, New Alipore, Kolkata 700 053, India 1[E-mail: [email protected]]

Received 2 February 2012; revised 13 August 2012

Fringing reefs of Andaman & Nicobar group of islands harbor 45 species of mushroom corals species up to the depth of 30 m. An individual of Cycloseris somervillei (Gardiner, 1909) was sampled from five study areas. Seven different morphological characters of each specimen of the target species were measured. Those characters were differed significantly among the specimens of study sites. Environmental parameter viz. temperature and rainfall was also measured to make a correlation between morphological differences and environmental factors. Depth plays a crucial role in the alteration of structural conformation. Underwater visibility also has an impact on the structural variation of the same species at different sites. This paper deals with the morphological variation of a species of mushroom coral i. e. Cycloseris somervillei in response to the environmental clues.

[Keywords: Mushroom coral, Cycloseris somervillei, Temperature, Rainfall, Depth, Morphological variation]

Introduction habitats and allow them to acclimatize to temporal The coral reef environment is extremely changes in the environment21. In taxonomic terms, heterogeneous and thus presents an adaptive such environmentally induced morphological changes challenge to sessile organisms that, beyond their can hinder accurate species identification. Present larval stage, are incapable of escaping their study is an attempt to make a concluding remark on surroundings. In order to improve fitness, many morphological variation of Cycloseris somervillei animals, especially scleractinian corals, have evolved (Gardiner, 1909) depending upon the physiological diverse, environmentally relevant, morphologies1,2. parameters. Mushroom corals are well known from South Asian waters, because they are usually striking and Materials & Methods abundantly present on corals reefs, including the One model specimen i.e. Cycloseris somervillei shallow flats and slopes. Specimens of the most (Gardiner, 1909) belongs to the family Fungiidae, species are free living and therefore easy to collect order Scleractinia, was taken to carry out the study and well represented in reference collections3,4. Due on morphological differences on according to the to this unattached mode of life, they are also easy to physiological parameters. Specimens were compared use in quantitative ecological studies5-16. Intra-specific at five stations such as Landfall Island (Lat. variation in scleractinian corals is a classic problem 13°39.481’N & Long. 093°01.496’ E), Long Island in their taxonomy, both in regard to recent (Lat. 12°24.412’N & Long. 092°56.837’E), Guiter and fossil species17,18. Environmental influences on Island (Lat. 12°20.323’N & Long. 092° 54.529’E), morphological characters are usually termed South Button Island (Lat. 12°13.378’N & Long. phenotypic plasticity and are documented in a wide 093°01.270’E) and Loha Barrack Crocodile Sanctuary range of coral species19. Variation in structural (Lat. 11º38.765’N & Long. 092º35.837’E) in conformation in relation to phenotypic attributes Andaman Archipelago during the year July, 2009 among the several species of Cycloseris was revealed to April, 2011. Sampling of the species was made by20. In ecological terms, morphological plasticity by employing Self–Contained Underwater Breathing might enable corals to occupy a broad range of Apparatus (SCUBA). Monthly rainfall data were 612 INDIAN J. MAR. SCI., VOL. 42, NO. 5 SEPTEMBER 2013

collected for three stations such as North Andaman the specimen i.e. 10.1: 6.4 cm (Fig. 1 a & b) was (Landfall Island), Long Island (Long and Guiter measured at Landfall Island where as the specimen Island) and South Andaman (South Button and Loha with minimum i.e. 4.7: 4.4 cm (Fig. 1 i & j) Loha Barrack Crocodile Sanctuary). Data on monthly mean Barrack Crocodile Sanctuary. Highest height of temperature of air was obtained from Meteorological the sample was found at Long Island was 3.7 cm Department of Port Blair. Transparency of water (Fig. 1 c) and the lowest 1.8 cm (Fig. 1 i) was columns of the study areas were measured using observed from the specimen of Loha Barrack Secchi disk22,23. To make morphometric measurement, Crocodile Sanctuary. All the specimens of all the the collected samples were kept in fresh water or 3% study areas showed only single mouth except the sodium hypochlorite solution to remove residual specimens of Guiter Island, where two mouths tissues. Skeletons were air-dried before the study24. (Fig. 1 e) were observed in general. In addition, Primarily species confirmation as well as structural maximum number of primary septa of one coralla study was made following the monographs of25,2. (51 ± 3) was observed from the specimens (Fig. 1 e) Morphological characters were studied in detail under of the same area. Compactness in the arrangement stereo microscope (Leica, M 205 A) as well as of the septal structure (both primary and secondary photographs were taken by a digital camera (Sony septal distance and number) was measured. It was Cyber Shot, DSC-T900, 12.1 megapixels, marine observed that the septal arrangement was very pack). Morphological characters viz. Coralla Length compact in the specimens of Guiter Island in (CL), Coralla Width (CW), Coralla Height (CH), comparison with the samples of other study areas Mouth (M), Number of Primary Septa (PS), Number (Table 1). Transparency of water column was highest of secondary septa in between primary septa (SS) at South Button Island (17.0 meter) where as the and distance between septa (DS) were used followed lowest was at Guiter Island (2.3 meter). by the scleractinian morphomatrix26-28. Four to five In Andaman and Nicobar Islands, usually two samples of each site were examined for their detailed seasons i.e. summer and monsoon could be noticed. study. On completion of detailed structural study, The dry season, composed of January, February and the type specimens were registered in National March and rest of the months are Rainy season. Zoological Collection of India and deposited at Maximum temperature (34.2°C) was recorded in the Zoological Survey of India, ANRC, Port Blair. month of April, 2010 where as the minimum was (22°C) noticed in the month of February, 2010. Results Temperature in remaining months ranged from 22°C Cycloseris somervillei (Gardiner, 1909) is usually to 34.2°C (Table 2). Average monthly temperature oval in sh. Pecentral fossa is distinctly arched. was maximum 31.26°C in the year of 2010 Septa are numerous and thin except towards the (Fig. 2). Maximum monthly rainfall (1020.5 mm) was centre. Lower order septa are much thicker stage measured in the month of June, 2009 where as towards the centre. Septal margins bear small, the minimum level (0.0 mm) was measured in the regular, triangular dentition which corresponds to month of January & February of 2009 and February & vertical rows of small granules on the septal sides. March of 2010 (Table 3). Monthly maximum average Axial fossa is narrow and elongate. Columellae is rainfall (470 mm) was reported at North Andaman well developed and spongiose in character. Costae are during the period of 2010-11 and lowest (254.54 mm) thin and slightly wavy towards the centre of the at Long Island during the period 2010-11 (Fig. 3). corallum and slightly alternate towards the periphery. Three order costae can be easily recognized well. Discussion Costal spines are present throughout the coralla under Mushroom corals are endemic to the Indo-Pacific surface covering the costae. Spines are very small and region. These coals have mainly been studied in blunt in nature. 4-5 specimens from five different relation with light penetration, sedimentation, and stations were measured to demonstrate the structural traumatic damage3,29,30,7. Andaman & Nicobar Islands variation among the same species. Most of the provides the ideal habitat for sustainable persistent samples collected from diffrent study areas were of the mushroom with promising diversity. A total of oval or arched to some extent dome shaped, however, 44 species of mushroom corals were already reported the sample of the South Button Island was flat is from here31,32 added another species of mushroom appearance (Fig. 1 g & h). Maximum length: width of coral i.e. Cycloseris vaughani (Boschma, 1923) as MONDAL et al.: PHENOTYPIC PLASTICITY OF CYCLOSERIS SOMERVILLEI IN ANDAMAN & NICOBAR ISLANDS 613

Fig. 1—Morphological Variation of Cycloseris somervillei; a & b – Landfall Island; c & d – Long Island; e & f – Guiter Island; g & h – South Button Island; i & j – Laha Barrack Crocodile Sanctuary 614 INDIAN J. MAR. SCI., VOL. 42, NO. 5 SEPTEMBER 2013

Table 1—Comparative Morphometric Measurement of Cycloseris somervillei (Gardiner, 1909) Study Stations of Andaman Characters Islands CL (cm) CW (cm) CH (cm) M PS SS DS (mm) Landfall Island 9.3 ± 2.1 6.4±1.6 2.8±0.7 1 40±8 2±1 3.1±0.9 Long Island 10.1± 1.2 6.2±1.4 3.7±0.4 1 46±6 2±2 2.9±1.1 Guiter Island 8.2±2.3 5.6±1.1 3.1±0.6 2 51±3 3±2 2.4±1.3 South Button Island 7.1±1.7 6.1±1.5 2.5±0.3 1 36±6 2±1 3.2±1.1 Loha Barrack Crocodile sanctuary 4.7±1.8 4.4±1.2 1.8±0.4 1 27±7 2±1 2.7±.5 [Coralla Length (CL), Coralla Width (CW), Coralla Height (CH), Mouth (M), No. of Primary Septa (PS), No. of Secondary septa in between primary septa (SS) and Distance between Septa (DS)]

Table 2—Maximum and Minimum Temperature of Andaman & Nicobar Islands Maximum Temperature (°C) Minimum Temperature(°C) Year → Month↓ 2009 2010 2011 2009 2010 2011 January 30.1 30.7 30.4 23 24 24 February 31.5 31.7 31.1 22 23 23 March 32.7 32.8 30.6 24 24 24 April 32.5 34.2 32.1 26 26 25 May 31.4 33.1 25 26 June 29.1 31.1 25 25 July 29.9 30 25 24 August 30.3 29.6 25 25 September 27.8 30.5 25 25 October 31 30.4 24 24 November 31.5 30.6 25 25 December 31 30.5 25 24

Table 3—Station wise Monthly Rainfall Station North Andaman Long Island South Andaman Year → Month↓ 2009 2010 2011 2009 2010 2011 2009 2010 2011 January 0 203 189 0 46 117.2 0 89.2 132.1 February 0 0 5 0 0 78.4 0 0 77.4 March 4 0 302 2 0 222.6 27.2 0 456.2 April 92 5 44 128.2 5 36 157.4 7 54.2 May 70 504 220 344 405.1 320.1 June 1020.5 634 985.7 155 505.4 390.8 July 749 806 395 390.2 178.8 600.2 August 744 993.1 379.8 583 418.5 423 September 629 394 342.2 191 416.2 314.5 October 562 662 262.2 427.6 237.6 420.7 November 35 77 21 112.4 88.6 222.3 December 53 163 51 112.4 61.9 328.8 new to Indian water to strengthen the total compacted character in the septal arrangement. scleractinian database. Morphometrics were taken Though the rainfall was recorded in all the studied for the consideration to illustrate phenotypic plasticity areas but among them the level of rainfall was of skeletal variations in scleractinians on clonal comparatively less in Long Island its associated areas. population structures33,34 and species diagnosis26,27,28,35,36. Guiter Island is a nearby island of Long Island, the A physiological difference with regard to transparency was 2.3 meter, might be attributed vulnerability to elevated temperature has also been to sedimentation load from coastal areas and shown among individuals of the same mushroom mangrove environment near the vicinity. Due to these coral species within close range of each other9. adverse conditions, the corals earned the strategies Samples of the Guiter Island showed the maximum for combating with the situation with this compact MONDAL et al.: PHENOTYPIC PLASTICITY OF CYCLOSERIS SOMERVILLEI IN ANDAMAN & NICOBAR ISLANDS 615

temperature was noticed from those study areas, it can be said that environmental factors have great impact on morphological construction of scleractinian corals.

Acknowledgements Authors are grateful to the Ministry of Environment and Forests, Govt. of India for providing financial assistance to undertake the study through the projects of National Coral Reef Research Institute, Zoological Survey of India, Port Blair. Thanks are also extended towards the Officer-in-Charge, Indian Meteorological Department, Port Blair for providing Fig. 2—Monthly Average Maximum Temperature necessary atmospheric database.

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