C. Raghunathan

Ecology of Faunal Communities on the Andaman and Nicobar Islands

This chapter deals with 30 species of polycheates that belong to eight families and 23 genera. All species were recorded for the first time from the Andaman and Nicobar Islands, of which 15 species are new to Indian waters. An updated checklist of polycheates of Andaman and Nicobar Islands is also presented in this chapter.

Occurrence of Seven Scleractinian Corals in Ritchie’s Archipelago, Andaman Islands of India

Occurrence of seven Scleractinian corals viz. Lobophyllia diminuta Veron, 1985; Acanthastrea regularis Veron, 2000 and Scolymia australis (Milne Edwards and Haime, 1849) [family: Mussidae], Montatrea cavernosa (Linnaeus, 1766) [family: Faviidae], Plerogyra simplex Rehberg, 1892 [family: Euphyllidae], Siderastrea siderea (Ellis and Solander, 1786) [family: Siderastreidae] and Dichocoenia stokesi Milne Edwards and Haime, 1848 [family: Meandrinidae] has been recorded from Ritchie’s Archipelago of Andaman group of Islands of India. Relevant information on these corals is depicted in this paper.

Identification of seven scleractinian corals from Andaman and Nicobar Islands as new record to IndianWater

Andaman and Nicobar Islands are the most diverse areas with enriched marine organisms. Presence of corals in any area shows the enriched productivity of marine ecosystem of that area. The coral helps the other associated faunal communities for their survival as well as their way of life towards the future generation. Seven species of scleractinian corals are recognized as the new records to Indian water as the survey made in Neil, Tarmugli and Car Nicobar Islands of Andaman & Nicobar Archipelago. They are — Acropora tanegashimensis (Veron, 1990), Acropora insignis (Nemenzo, 1967), Favites paraflexuosa (Veron,2002), Favites spinosa (Klunzinger, 1879), Solenastrea bournoni (Milne Edwards and Haime, 1849), Porites porites (Pallas, 1766) and Seriatopora aculeate (Quelch, 1846). These scleractinian corals belong to Acroporidae, Faviidae, Poritidae and Pocilloporidae families. The present investigation deals with their morphological characteristics with relative nomenclatural attributes to draw the ideal identifying remarks.

Post Bleaching Assessment of Corals in Andaman and Nicobar Islands

Reefs of Andaman and Nicobar Islands harbour 418 species of scleractinian corals spread over an area of 2,000xa0km2. In April to May, 2010, due to the delayed onset of the southwest monsoon the sea surface temperature of the coastal and oceanic region increased to 31.7xa0°C in respect to the earlier record of maximum 29.0xa0°C during the said period. This resulted in mass bleaching of hermatypic corals during May, 2010. Rapid under water surveys have been conducted in reefs of Andaman and Nicobar Islands to assess the health of corals between May 2010 and August 2011. It is estimated that 76.62xa0±xa0(SD) 10.83xa0% of coral species are bleached up to a water depth of 10–15xa0m. Species from the genus Acropora appeared more susceptible to bleaching than those belong to the genus Porites. During the month of June 2010 the sea surface temperature was reduced to 29xa0°C perhaps due to the rainfall which stimulated rebuilding of zooxanthellae population in bleached corals. Recovery of 85.54xa0±xa0(SD) 6.33xa0% of bleached corals was seen during the study period of 11xa0months after the bleaching event. Porites spp. showed a high recovery rate, while Acropora spp. had the highest mortality rate. Coral mortality can have profound ecological and socio-economical implications and highlights the need for sustained monitoring for coral reef conservation in India. Hence, steps must be taken to improve management tools to protect these resources of global significance.

Status and Distribution of Trochus niloticus (Linnaeus 1767) in Andaman and Nicobar Islands

Trochus niloticus (Linnaeus 1767) is a marine gastropod that belongs to the Order Archaeogastropoda and Family Trochidae. The present status survey on Trochus niloticus was carried out during August 2009 to March 2010 at 79 stations covering entire Andaman and Nicobar Islands to assess their distribution and standing stock on its natural beds parameters along with the primary and secondary productivities in their ambience. Extensive undersea and intertidal surveys revealed that the occurrence of Trochus niloticus throughout the sublittoral zone of continental shelf of Andaman and Nicobar Archipelago up to the depth of 20 m. The density of Trochus niloticus found in the depth ranges between 10 and 20 m at all the places of study. The mean density of Trochus niloticus varied from 6 shells/100 m2 in the coastal waters of South Andaman to 15 shells/100 m2 in Nancowry Islands. The abundance of Trochus niloticus was maximum in Nancowry group of Islands, and it recorded up to 20 shells/100 m3, and also the larger specimen up to the maximum size of 13.62 cm has been observed at this region. The observations of the present study revealed that the density and size of the Trochus niloticus is comparatively higher in the Nicobar group of Islands than Andaman group. Apart from that, Middle and North Andaman were shown to have moderately high density of animals.

Diversity of Sponges in Marine Protected Areas of North Andaman, India

The continental shelf of the Andaman and Nicobar Islands harbours rich sponge diversity. Despite being one of the most important components of the reef ecosystem, comprehensive inventories of marine sponges of the protected areas of these Islands are still lacking. The present study was devoted to provide an outline of the sponge species composition of the island sanctuaries and adjoining areas of North Andaman and to compare the species assemblage from east and west coasts. The intertidal and subtidal sponges were surveyed from 41 sites covered under 23 locations (17 island sanctuaries and 6 undesignated locations) during March 2016 – September 2017. A total of 43 sponges distributed among 16 orders, 25 families and 35 genera were identified and recorded. The number of sponges per location was ranging from 6 to 20 in the east coast with a mean (meanu2009±u2009SE) of 14u2009±u20092.07 and 3 to 21 in the west coast with a mean of 9.13u2009±u20091.44, indicating a significant difference on a spatial scale, notwithstanding the geographical proximity of the survey locations. Haplosclerida was the most represented order (9 species), contributing approximately 21% to the total sponge biodiversity, followed by Axinellida and Dictyoceratida (6 species). Two species namely, Carteriospongia foliascens (18 locations) followed by Neopetrosia exigua (16 locations) were dominant from the survey locations, indicating their ubiquitous occurrences throughout the survey locations. Sixteen growth forms were observed of which, cushions were the most dominant growth form (18.6%) followed by thin sheets (16.28%) and massive-globose (11.63%), suggestive of their survival ability in the coral-reef environments. Nevertheless, the significant differences in the species composition and growth forms among the survey locations are likely to be attributed to numerous ecological and environmental factors. Further research on sponges should be devoted in understanding their interaction with other fauna.

New distribution records of three Sarcophyton species (Alcyonacea: Alcyoniidae) in Indian waters from Andaman Islands

Three alcyonacean corals— Sarcophyton acutum Tixier-Durivault, 1970, S. latum (Dana, 1846) and S. spongiosum Thompson & Dean, 1931—under the family Alcyoniidae are reported from Andaman Islands as new records to Indian waters. The paper deals with the detailed taxonomic description of these three newly recorded alcyonacean species along with a note on their previously known distribution.

Diversity of Scleractinian Corals in Great Nicobar Island, Andaman and Nicobar Islands, India

Great Nicobar Island is the southernmost island of Andaman and Nicobar group of islands and largest island of Nicobar group included in UNESCO-MAB-Network of biosphere reserve. The island is inhabited by a total of 173 species of scleractinian corals from 6 different study areas among the 577 species reported from entire Andaman and Nicobar Islands. The Shannon–Weiner diversity index ranged from 2.84 to 4.45 while the Simpson’s density index ranges from 0.93 to 0.99. Among the study areas, it was seen that the Laxman Beach is most diverse in comparison with the other 5 areas. Presence of 29.98xa0% scleractinian coral species in Great Nicobar Island denotes the sense of ecological attributes behind the sustainable support towards the coral settlement, growth and development.

Bleaching: The Driving Force of Scleractinian New Recruitment at Little Andaman Island, Andaman and Nicobar Islands

Peak bleaching of corals was seen in 2010 in the Andaman and Nicobar Islands. The results were observed as adverse impacts on the reef environment. Little Andaman Island is the southern-most part of Andaman group of Islands. The continental shelf of this island showed a limited number of scleractinian corals as new recruitment at the destroyed reef areas after the 2004 tsunami. Only 34 species of hermatypic corals were reported in 2009. Consecutive underwater survey and experimental outcome reveals that 124 species of scleractinian corals were identified from the same areas after the mass bleaching effect. The presence of species composition of the study area is near about 4 times higher than the study which was made on newly recruited corals after tsunami. Bleaching was the only giant event which occurred in between 2009 and 2012, considered as the prime regulator for the new recruitment of scleractinians. The Shannon–Weaver’s species diversity index of the study area ranges from 5.09 to 6.00, Simpson’s species density index varies from 0.94 to 0.97 whereas the Pielou’s evenness index shows the results in between 0.93 and 0.98. The present paper depicts the species composition, diversity, density and evenness at post bleaching state to signify the constructive role of bleaching towards the settlement of new scleractinian coral life on the preceding places.