Andaman and Nicobar Islands, the gastropod diversity is high, due to the majority of shores are rocky. The wet rocky shore promotes algal growth, which is ultimate for feeding ground for gastropod growth and development leading to more diversity. The global warming, anthropogenic activities, industrial and domestic pollution, etc., have accelerated the loss of coastal and marine biodiversity components over the last few decades which has been of great concern. However, except global warming, the other factors were of least concern with reference to Andaman and Nicobar Islands biodiversity due to a pristine environment. Therefore, exploration of biodiversity in these islands is essential to create a baseline data for record and future research. Four locations of south to north Andaman Islands which represented Carbyns Cove from south Andaman, Rangat and Mayabunder from the Middle Andaman and Diglipur from the North Andaman were selected for this study. Gastropoda species were collected for a period of one year in three prevailing seasons of Andaman and Nicobar Islands. They are South West Monsoon (SW monsoon), North East Monsoon (NE Monsoon) and Non Rainy Seasons (NR Seasons). The present study of gastropods distribution in the South, Middle and North Andaman groups of Islands suggested that there are 71 species belonging to 52 genus and 33 families. At any one of the time and any one of the locations, only one occurrence was noticed for 38 species and remaining 33 species were overlapping with respect to stations and seasons. Evaluation of the cluster suggested that Cluster A (NR season in Carbyns Cove) and Cluster B (NE and SW Monsoon in Mayabunder) as a separate entity among the 12 combinations of stations and seasons due to their species representation. It was also concluded that out of 71 studied species, 3 species were not reported till date in these Island environment and 2 species from any other parts of India.
Andaman and Nicobar archipelago located in the central part of the Bay of Bengal consists of 572 islands. Southern tip of this archipelago is located just at 145 NM from the northern side of Indonesia and 750 NM distance from the eastern coast of India. This island is scarcely populated than the mainland India. This pristine environment supports establishment of well diversified coral communities. This archipelago is one among the 12 mega-biodiversities and also one among the 25 hotspots of the rich and highly endangered eco-regions of the world. Among the Asian countries, India is the only one country that has a long record of inventories of coastal and marine biodiversity dating back to at least two centuries.
The research history of malacological studies in India is among the oldest one which was initiated by the Asiatic Society of Bengal during the year 1784 and made a repository in the Indian Museum, Calcutta in the year 1814. Benson published a total of 90 research papers which was mainly concerned land and freshwater mollusks of the Indian subcontinent between 1830-1865 [
Among the mollusks, gastropods are more important in the coastal populations’ economy, i.e. as a shell-craft industry. Over and above, the marine gastropod resources in India consisted of different types of species which are exploited regularly for various purposes like drugs, ornamental purposes as well as for their meat. Andaman and Nicobar Islands, the gastropod diversity are high, due to the majority of shores are rocky. The wet rocky shore promotes algal growth, which is ultimate for feeding ground for gastropod growth and development leading to more diversity. Further, the mangrove environment also provides ideal conditions for the productivity of gastropods [
The global warming, anthropogenic activities, industrial and domestic pollution, etc., have accelerated the loss of coastal and marine biodiversity components over the last few decades which has been of great concern. However, except global warming, the other factors were of least concern with reference to Andaman and Nicobar Islands biodiversity due to a pristine environment. Therefore, exploration of biodiversity in these islands is essential to create a baseline data for record and future research. In this regard, gastropods are a significant indicator of environmental changes, hence, an attempt had been made to understand a comprehensive gastropod diversity by the way of studies on selected locations of the south to north Andaman coast lines.
The gastropod diversity of the Andaman Islands was studied in four locations of south to north Andaman Islands which represented Carbyns Cove from south Andaman, Rangat and Mayabunder from the Middle Andaman and Diglipur from the North Andaman (
This station is located in the south Andaman. This coast has a length of one km out of that, the central part which extends to around 300 m is covered with sand and remaining part are exposed as rock terrain. Near the southern part of the sandy beach environment a freshwater inlet is present through which inflow of rainwater occurs during the monsoon. However, during the high tide the whole beach is submerged with sea water.
This location is present in the southern part of Middle Andaman. This area covered a length of one km. This site is covered by rocky outcrops with boulders and pebbles which are in many ways similar to the Carbyns Cove, however, it has a less sandy beach of around 100 m long with a freshwater inlet in south side. However, during the non rainy season this inlet would be blocked with boulders and pebbles while during the rainy season it opens for the freshwater flow.
This station is located in the northern part of Middle Andaman. The exact location is near the eastern side of the fishery jetty. However, this area largely consists of exposed rocks with boulders and pebbles surrounded by mangrove vegetation.
This study area is located in the northern part of Andaman. The samples were collected at Kalipur beach. Sandy beach precedes an exposed coral basement on the eastern side while the western side has a plain and wider sand cover without any coral basement exposure along with a freshwater inlet. The high tide covers this coral basement along with the upper sandy beach. During the low tide more than a 600 to 700 m wide coral basement with gentle slope would be exposed.
All the above stations, once in four months, i.e. from August 2013 to August 2014, systematic samples were collected throughout the coastline. The seasons of Andaman considered as a unique one, eight months, having continuous rain and four month considered as the non rainy season. Overall annual rainfall is 3394 mm. The period January to April considered Non Rainy Season (NRS). The month May to August considered as South West Monsoon (SWM) and September to December considered as North East Monsoon (NEM). So, these collections were made at the end of each season, i.e. the Second Half of December to First Half of January is representing the end of NE monsoon. The Second Half of the April to First Half of May considered as the end of the Non Rainy season and Second Half of the July to First Half of August represented as the end of the SW monsoon period. The collection of samples was within one square meter transect at two sites in each station by hand picking as mentioned by Arumugam et al. [
Species Name | NER 2013 | NRR 2014 | SWR 2014 | NEM 2013 | NRM 2014 | SWM 2014 | NED 2013 | NRD 2014 | SWD 2014 | NEC 2013 | NRC 2014 | SWC 2014 |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Trochus radiates | 5.32 | --- | 1.53 | --- | --- | 2.77 | --- | --- | --- | 5.00 | --- | --- |
Monodonta australis | 1.33 | --- | --- | --- | --- | 8.33 | --- | 4.54 | 4.16 | 7.50 | --- | --- |
Tectus pyramis | ---- | --- | --- | --- | 10.52 | --- | --- | --- | 4.16 | --- | --- | --- |
Angaria delphinus | --- | --- | --- | 7.14 | --- | --- | --- | --- | --- | --- | --- | --- |
Turbo bruneus | 2.66 | --- | --- | --- | --- | 2.77 | 2.85 | 4.54 | 12.50 | 2.50 | --- | --- |
Lunella cinerea | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Turbo sp. | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | 33.33 | --- |
Turbonilla felicita | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.5 | --- | --- |
Nerita albicilla | 5.33 | 88.23 | 10.76 | --- | 5.26 | 8.33 | 17.14 | 13.63 | 20.83 | 25.00 | --- | 52.62 |
Nerita oryzarum | 1.33 | --- | 7.68 | --- | 36.84 | --- | 2.85 | --- | 8.32 | 2.50 | --- | --- |
Nerita polita | 16.00 | --- | 6.15 | --- | 5.26 | --- | --- | 9.09 | --- | --- | --- | --- |
Nerita histrio | --- | --- | --- | --- | --- | --- | 14.28 | --- | --- | --- | --- | --- |
Nerita chamaeleon | --- | --- | --- | --- | 10.52 | 5.55 | 2.85 | --- | --- | --- | --- | --- |
Nerita insculpta | --- | --- | 15.38 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Nerita costata | --- | --- | 13.84 | --- | --- | --- | --- | --- | --- | --- | --- | 15.78 |
Cellana radiata | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Cellana sp. | 4.00 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Menathais turberosa | 4.00 | --- | 3.07 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Tylothais virgata | 9.33 | --- | --- | 7.14 | --- | --- | --- | --- | --- | 15 | --- | --- |
Menathais intermedia | --- | --- | --- | --- | 5.26 | --- | --- | --- | --- | --- | --- | 23.68 |
Indothais lacera | --- | --- | --- | --- | --- | --- | 2.85 | --- | 4.16 | --- | --- | --- |
Tenguella granulata | --- | --- | 12.3 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Vokesimurex tryoni | --- | --- | --- | --- | --- | --- | --- | 4.54 | --- | 2.50 | --- | --- |
Chicoreus brunneus | --- | --- | 1.53 | --- | --- | 11.11 | --- | --- | 4.16 | 2.50 | --- | --- |
Murex tribulus | 2.66 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Semiricinula konkanensis | 2.66 | --- | 3.07 | --- | --- | --- | --- | --- | --- | --- | --- | -- |
Thais sp. | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.50 | 33.33 | --- |
Morula nodicostata | --- | --- | --- | --- | --- | --- | --- | --- | 20.83 | --- | --- | --- |
Morula sp. | --- | --- | 1.53 | --- | --- | 8.33 | --- | --- | --- | --- | --- | --- |
Vasum turbinellus | 1.33 | --- | --- | --- | --- | --- | --- | 20.72 | --- | --- | --- | --- |
Clypeomorus bifasciata | 4.00 | --- | --- | --- | 5.26 | --- | 54.27 | 20.17 | --- | 5.00 | 33.33 | --- |
Clypeomorus petrosa | --- | --- | --- | --- | 5.26 | --- | --- | 13.63 | --- | 2.50 | --- | --- |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Cerithium coralium | --- | --- | --- | --- | --- | --- | --- | --- | 4.16 | --- | --- | --- |
Rhinoclavis vertagus | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.50 | --- | --- |
Batillaria multformis | 8.00 | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Nebularia aurantia | --- | --- | 7.65 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Strigatella paupercula | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Haliotis planata | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.50 | --- | --- |
Turritella sp | --- | --- | --- | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
Nassarius sp. | --- | --- | 3.07 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Nassarius coronatus | 1.33 | --- | --- | --- | 5.26 | --- | --- | --- | --- | --- | --- | --- |
Nassarius olivaceus | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Nassarius pullus | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Nassarius conoidalis | --- | --- | --- | --- | 5.26 | --- | --- | --- | --- | --- | --- | --- |
Oliva vidua | --- | --- | --- | --- | --- | 8.33 | --- | --- | --- | --- | --- | --- |
Oliva sp. | 2.66 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Bufonaria rana | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Bufonaria echinata | 4.00 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Bursa granularis | 2.66 | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Gammula vagata | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Turrilatirus craticulatus | --- | --- | --- | --- | --- | --- | --- | --- | 4.16 | --- | --- | --- |
Latirolagena smaragdulus | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Scutellastra flexuosa | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Terebralia paluster | --- | --- | --- | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
Engina mendicaria | 1.33 | --- | --- | --- | --- | --- | --- | --- | 8.32 | --- | --- | --- |
Pollia undosa | 5.33 | --- | --- | --- | --- | --- | 2.85 | --- | 4.16 | --- | --- | --- |
Siphonaria sp.1 | --- | 5.88 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Siphonaria sp.2 | --- | --- | 1.53 | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
Canarium labiatum | 2.66 | 5.88 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Gibberulus gibberulus | --- | --- | --- | 14.28 | --- | 2.77 | --- | --- | --- | --- | --- | --- |
Laevistrombus canarium | --- | --- | --- | 21.42 | --- | --- | --- | --- | --- | --- | --- | --- |
Conus ebraeus | --- | --- | --- | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
Harpa major | 1.33 | --- | 1.53 | --- | --- | --- | --- | --- | --- | 5.00 | --- | 7.89 |
Semicassis bisulcata | 2.66 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Polinices mammilla | 1.33 | --- | --- | --- | 5,26 | --- | --- | --- | --- | --- | --- | --- |
Tanea lineata | --- | --- | --- | 7.14 | --- | 11.11 | --- | --- | --- | --- | --- | --- |
Patelloida saccharina | --- | --- | --- | --- | --- | --- | --- | --- | --- | 15.00 | --- | --- |
Onchidium sp. | --- | --- | --- | 21.42 | --- | --- | --- | --- | --- | --- | --- | --- |
Littoraria undulate | --- | --- | --- | 21.42 | --- | 13.88 | --- | --- | --- | --- | --- | --- |
Monetaria moneta | --- | --- | --- | --- | --- | --- | --- | 9.08 | --- | --- | --- | --- |
Gyrineum natator | --- | --- | --- | --- | --- | 5.55 | --- | ---- | --- | --- | --- |
Further, the data were analysed by Primer 6 software [
Gastropoda species were collected from the coasts of Carbyns Cove, Rangat, Mayabunder and Diglipur for a period of one year in three prevailing seasons of Andaman and Nicobar Islands. They are SW monsoon, NE Monsoon and Non rainy Seasons. The collected samples were identified up to species level and their data were converted into percentages (
Based on this study, among the four stations, seventy one species belonging to fifty two genus and thirty three families of gastropods were observed. Among the seventy one species, 38 species fell in unique category such that it may be noticed in any one of the stations, in any one of the season, i.e. their appearances/dis- appearance were not found to be site specific or seasonal specific (
Out of the remaining species, 20 species were observed in two occurrences by the way of any two seasons or any two locations or one season in two locations (
The species Tylothais virgata only observed during the NE monsoon of all the stations except Diglipur. Clypeomorus bifasciata species noticed only in the fifty percent of the seasons of the study period (NE Rangat, NRS Mayabunder, NE Diglipur, NRS Diglipur, NE and NRS of Carbyns Cove. Pollia undosa species were observed in NE monsoon season of Rangat and Diglipur as well as SW monsoon at Diglipur (
Trochus radiates noticed in the NE monsoon of Rangat and Carbyns Cove
Sl. No. | Species Name | NER 2013 | NRR 2014 | SWR 2014 | NEM 2013 | NRM 2014 | SWM 2014 | NED 2013 | NRD 2014 | SWD 2014 | NEC 2013 | NRC 2014 | SWC 2014 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Angaria delphinus | --- | --- | --- | 7.14 | --- | --- | --- | --- | --- | --- | --- | --- |
2 | Lunella cinerea | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
3 | Turbo sp. | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | 33.33 | --- |
4 | Turbonilla felicita | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.50 | --- | --- |
5 | Nerita histrio | --- | --- | --- | --- | --- | --- | 14.28 | --- | --- | --- | --- | --- |
6 | Nerita insculpta | --- | --- | 15.38 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
7 | Cellana radiate | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
8 | Cellana sp. | 4.00 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
9 | Tenguella granulata | --- | --- | 12.30 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
10 | Murex tribulus | 2.66 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
11 | Morula nodicostata | --- | --- | --- | --- | --- | --- | --- | --- | 20.83 | --- | --- | --- |
12 | Cerithium coralium | --- | --- | --- | --- | --- | --- | --- | --- | 4.16 | --- | --- | --- |
13 | Rhinoclavis vertagus | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.50 | --- | --- |
14 | Nebularia aurantia | --- | --- | 7.65 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
15 | Strigatella paupercula | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
16 | Haliotis planata | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.50 | --- | --- |
17 | Turritella sp | --- | --- | --- | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
18 | Nassarius sp. | --- | --- | 3.07 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
19 | Nassarius olivaceus | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
20 | Nassarius pullus | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
21 | Nassarius conoidalis | --- | --- | --- | --- | 5.26 | --- | --- | --- | --- | --- | --- | --- |
22 | Oliva vidua | --- | --- | --- | --- | --- | 8.33 | --- | --- | --- | --- | --- | --- |
23 | Oliva sp. | 2.66 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
24 | Bufonaria rana | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
25 | Bufonaria echinata | 4.00 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
26 | Gammula vagata | 1.33 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
27 | Turrilatirus craticulatus | --- | --- | --- | --- | --- | --- | --- | --- | 4.16 | --- | --- | --- |
28 | Latirolagena smaragdulus | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
29 | Scutellastra flexuosa | --- | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
30 | Terebralia paluster | --- | --- | --- | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
31 | Siphonaria sp.1 | --- | 5.88 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
32 | Laevistrombus canarium | --- | --- | --- | 21.42 | --- | --- | --- | --- | --- | --- | --- | --- |
33 | Conus ebraeus | --- | --- | --- | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
34 | Semicassis bisulcata | 2.66 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
35 | Patelloida saccharina | --- | --- | --- | --- | --- | --- | --- | --- | --- | 15.00 | --- | --- |
36 | Onchidium sp. | --- | --- | --- | 21.42 | --- | --- | --- | --- | --- | --- | --- | --- |
37 | Monetaria moneta | --- | --- | --- | --- | --- | --- | --- | 9.08 | --- | --- | --- | --- |
38 | Gyrineum natator | --- | --- | --- | --- | --- | 5.55 | --- | ---- | --- | --- | --- | -- |
Sl. No. | Species Name | NER 2013 | NRR 2014 | SWR 2014 | NEM 2013 | NRM 2014 | SWM 2014 | NED 2013 | NRD 2014 | SWD 2014 | NEC 2013 | NRC 2014 | SWC 2014 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Tectus pyramis | ---- | --- | --- | --- | 10.52 | --- | --- | --- | 4.16 | --- | --- | --- |
2 | Nerita costata | --- | --- | 13.84 | --- | --- | --- | --- | --- | --- | --- | --- | 15.78 |
3 | Menathais turberosa | 4.00 | --- | 3.07 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
4 | Menathais intermedia | --- | --- | --- | --- | 5.26 | --- | --- | --- | --- | --- | --- | 23.68 |
5 | Indothais lacera | --- | --- | --- | --- | --- | --- | 2.85 | --- | 4.16 | --- | --- | --- |
6 | Vokesimurex tryoni | --- | --- | --- | --- | --- | --- | --- | 4.54 | --- | 2.5 | --- | --- |
7 | Semiricinula konkanensis | 2.66 | --- | 3.07 | --- | --- | --- | --- | --- | --- | --- | --- | -- |
8 | Thais sp. | --- | --- | --- | --- | --- | --- | --- | --- | --- | 2.5 | 33.33 | --- |
9 | Morula sp. | --- | --- | 1.53 | --- | --- | 8.33 | --- | --- | --- | --- | --- | --- |
10 | Vasum turbinellus | 1.33 | --- | --- | --- | --- | --- | --- | 20.72 | --- | --- | --- | --- |
11 | Batillaria multformis | 8.00 | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
12 | Bursa granularis | 2.66 | --- | 1.53 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
13 | Engina mendicaria | 1.33 | --- | --- | --- | --- | --- | --- | --- | 8.32 | --- | --- | --- |
14 | Siphonaria sp.2 | --- | --- | 1.53 | --- | --- | 2.77 | --- | --- | --- | --- | --- | --- |
15 | Canarium labiatum | 2.66 | 5.88 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
16 | Gibberulus gibberulus | --- | --- | --- | 14.28 | --- | 2.77 | --- | --- | --- | --- | --- | --- |
17 | Polinices mammilla | 1.33 | --- | --- | --- | 5.26 | --- | --- | --- | --- | --- | --- | --- |
18 | Tanea lineata | --- | --- | --- | 7.14 | --- | 11.11 | --- | --- | --- | --- | --- | --- |
18 | Littoraria undulate | --- | --- | --- | 21.42 | --- | 13.88 | --- | --- | --- | --- | --- | --- |
20 | Nassarius coronatus | 1.33 | --- | --- | --- | 5.26 | --- | --- | --- | --- | --- | --- | --- |
and SW monsoon period in Mayabunder and Rangat. Chicoreus brunneus observed in SWM of Rangat, Mayabunder and Diglipur as well as NEM of Carbyns Cove stations. SWM of Mayabunder, NEM of Rangat and Carbyns exhibited Monodonta australis species and in Diglipur it had been noticed in Non rainy season and SW monsoon. Harpa major species were noticed in NEM and SWM of Rangat and Carbyns Cove (
Except NEM in Mayabunder and NRS of Carbyns Cove all the remaining seasons represented by Nerita albicilla (
The NEM in Rangat, Diglipur and Carbyns Cove as well as NRS in Diglipur and SWM in Mayabunder and Diglipur represented the species Turbo bruneus, i.e. all the three seasons in Diglipur this species was present. Nerita oryzarum was observed during the period of NEM of Rangat, Diglipur and Carbyns Cove,
Sl. No. | Species Name | NER 2013 | NRR 2014 | SWR 2014 | NEM 2013 | NRM 2014 | SWM 2014 | NED 2013 | NRD 2014 | SWD 2014 | NEC 2013 | NRC 2014 | SWC 2014 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Trochus radiates | 5.32 | --- | 1.53 | --- | --- | 2.77 | --- | --- | --- | 5.00 | --- | --- |
2 | Monodonta australis | 1.33 | --- | --- | --- | --- | 8.33 | --- | 4.54 | 4.16 | 7.50 | --- | --- |
3 | Angaria delphinus | --- | --- | --- | 7.14 | --- | --- | --- | --- | --- | --- | --- | --- |
4 | Nerita albicilla | 5.33 | 88.23 | 10.76 | --- | 5.26 | 8.33 | 17.14 | 13.63 | 20.83 | 25.00 | --- | 52.62 |
5 | Nerita oryzarum | 1.33 | --- | 7.68 | --- | 36.84 | --- | 2.85 | --- | 8.32 | 2.50 | --- | --- |
6 | Tylothais virgata | 9.33 | --- | --- | 7.14 | --- | --- | --- | --- | --- | 1.50 | --- | --- |
7 | Chicoreus brunneus | --- | --- | 1.53 | --- | --- | 11.11 | --- | --- | 4.16 | 2.50 | --- | --- |
8 | Clypeomorus bifasciata | 4.00 | --- | --- | --- | 5.26 | --- | 54.27 | 20.17 | --- | 5.00 | 33.33 | --- |
9 | Pollia undosa | 5.33 | --- | --- | --- | --- | --- | 2.85 | --- | 4.16 | --- | --- | --- |
10 | Harpa major | 1.33 | --- | 1.53 | --- | --- | --- | --- | --- | --- | 5.00 | --- | 7.89 |
SWM in Rangat and Diglipur and NRS in Mayabunder (
The station Carbyns Cove exhibited a total of nineteen species consist of nine families. Out of nineteen species, single occurrence was noticed in 15 species and dual occurrence noticed for 4 species. A total of 24 families was missing in this station.
The station Rangat reported 42 species from 21 families. Out of 42 species single seasons were noticed for 32 species and dual occurrence noticed in 09 species and one species in all seasons. Twelve families were missing from this station.
The gastropods of 29 species belonging to 17 families were observed at Mayabunder station. Out of these 29 species, single occurrence noticed in 25 species and dual occurrence noticed in four species. There were 16 families missing.
Diglipur station reported 20 species belonging to 10 families in all the seasons. Out of 20 species, 13 species single time reported and two and three time presence noticed respectively 05 and 02 species. In this location 13 families were missing.
The study period represented the highest number of species (60) during the NE monsoon represented than remaining seasons. Next higher number of species (53) noticed in the SW monsoon and lowest numbers noticed in Non rainy season (26).
The results of the studied gastropods in the Primer software and the univariate analysis (
The group average of the Cluster plot (
The unit 3 (C-3) also has two sub-sub clusters with SWM Digilipur and NEM Carbyns Cove. The unit 4 (C-4) represented only one season that is NRS Mayabunder. The last unit 5 (C-5) has two subdivisions represented NEM and SWM Rangat.
Season | Total Species (S) | Total Individuals (N)? Normalised | Margalef’s Species Richness Index (d) | Pielou’s Evenness Index (J') | Shannon Wiener Index (H’) | Simpson Diversity Index (1 − λ) |
---|---|---|---|---|---|---|
NER | 29 | 100 | 6.0801 | 0.9109 | 3.0673 | 0.9466 |
NRR | 3 | 100 | 0.4343 | 0.4038 | 0.4437 | 0.2166 |
SWR | 21 | 100 | 4.3429 | 0.8711 | 2.6521 | 0.9184 |
NEM | 7 | 100 | 1.3028 | 0.9424 | 1.8338 | 0.8349 |
NRM | 10 | 100 | 1.9543 | 0.8596 | 1.9794 | 0.8105 |
SWM | 16 | 100 | 3.2572 | 0.9407 | 2.6082 | 0.9259 |
NED | 8 | 100 | 1.5200 | 0.6825 | 1.4192 | 0.6578 |
NRD | 9 | 100 | 1.7372 | 0.9330 | 2.0499 | 0.8650 |
SWD | 12 | 100 | 2.3886 | 0.9071 | 2.2542 | 0.8802 |
NEC | 16 | 100 | 3.2572 | 0.8618 | 2.3893 | 0.8826 |
NRC | 3 | 100 | 0.4343 | 1 | 1.0986 | 0.6734 |
SWC | 4 | 100 | 0.6514 | 0.8445 | 1.1708 | 0.6421 |
Based on the above results it was inferred that the station Rangat was highly enriched with gastropod species when comparing all the four stations followed by Mayabunder, Diglipur and Carbyns Cove stations. However, based on the occurrence of the species, it was noted that the stations Rangat and Carbyns Cove may be similar in environmental condition than the remaining two stations. Similarly, NE and SW monsoon plays a major role in the diversity and distribution of species in Rangat stations than in the Non rainy season. Mayabunder and Diglipur stations exhibited less diversity and distribution in NE monsoon than SW monsoon.
However, the Non Rainy Season shows diversity and distribution in between the above rainy seasons. Carbyns Cove represented SWM and NRS less favorable for diversity and distribution than NEM period.
Out of seventy one species studied, 10 species identified only upto genus level. The remaining 61 species, 57 species already reported in Andaman and Nicobar Islands by Rao (2003). The species Nerita oryzarum was reported by Ragunathan and Venkatraman [
The west coast of India in Raigad District, Maharashtra exhibited 14 species occurrence from the studies of Kade and Mane [
The station Rangat, Mayabunder, Diglipur and Carbyns Cove represented 42, 29, 20 and 19 species among the studied species. This suggested that Rangat station has an exposure of rocky outcrop which may provide a better niche for larger diversity of gastropod species. Even though Carbyns Cove also has the similar exposure because of little areal exposure during the low tide time may be reduced the population of this species. The studied Mayabunder location may have rocky and mangrove exposure support the presence of Littoraria undulata exclusively in this location and have next in concentration of diversity. Diglipur station was covered with coralline exposure than the rock exposure has fallen in between the Carbyns Cove and Mayabunder diversity status. Chelladurai et al. [
These studies well follow the existing inference from the world wide study pattern of the gastropoda. As reported by the Sanpanich et al. [
The results of univariate analysis based on Margalef’s Species Richness Index, Pielou’s Evenness Index, Shannon-Wiener Index and Simpson Diversity Index supported each other for the distribution of gastropods in the study locations for all the seasons. The cluster analysis also grouped the unique character of occurrences with reference to locations and seasons. While comparing these clusters, it was noted that that the individual clusters Cluster A and Cluster B has no similar species between them, but it shared similarities of the species with C1 and C2 clusters. The cluster B represented single common species (Nerita albicilla). Cluster C, among all the sub clusters (5 Nos.), the cluster four and five have three common species Nerita albicilla, Nerita oryzarum and Nerita polita. The sub cluster three, four and five showing two common species Nerita albicilla and Nerita oryzaraum and three and four exhibited two common species Nerita albicilla and Turbo brunneus. However, the cluster two and five exhibited one common species are Nerita albicilla. Turbo species exclusively in Cluster A among the three available species and Cluster B exhibited twelve species exclusively among the 20 available species. Total forty nine species exclusively found in Cluster C among 59 which can be divided into five sub clusters.
The present study of gastropods distribution in the South, Middle and North Andaman groups of Islands suggested that there are 71 species belonging to 52 genus and 33 families. At any one of the time and any one of the locations, only one occurrence was noticed for 38 species and remaining 33 species were overlapping with respect to stations and seasons. Nerita albicilla observed at all the stations with the majority of the seasons except NEM of Mayabunder and NRS of Carbyns Cove. Turbo species exclusively in Cluster A among the three available species and Cluster B exhibited twelve species exclusively among the 20 available species. Total forty nine species exclusively found in Cluster C among 59 which can be divided into five sub clusters. This study also concluded that three species (Turbonilla felicita, Vokesimurex tryoni and Batillaria multiformis) were new to the Andaman Islands and among them two species (Vokesimurex tryoni and Batillaria multiformis) were not recorded any part of India.
The authors thank the Central Marine Living Resources and Ecology, Ministry of Earth Sciences, Kochi for funding this work (MOES/CMLRE/10-ITIS/5/2012, Date: 01/10/2012). They also acknowledge the authorities of Pondicherry University for providing the facilities needed for the execution of this project.
Jeeva, C., Mohan, P.M., Sabith, K.K.D.B., Ubare, V.V., Muruganantham, M. and Kumari, R.K. (2018) Distribution of Gastropods in the Intertidal Environment of South, Middle and North Andaman Islands, India. Open Journal of Marine Science, 8, 173-195. https://doi.org/10.4236/ojms.2018.81009