Distribution Pattern and Community Structure of Sea Cucumbers

Distribution Pattern and Community Structure of Sea Cucumbers

Indian Journal of Geo Marine Sciences Vol. 46 (03), March 2017, pp. 569-575 Distribution pattern and community structure of sea cucumbers (Class: Holothuroidea) in different biogeographic regions of the selected Islands of Lakshadweep Archipelago, India Idreesbabu K.K.a,b & S. Sureshkumarb,c a Coral Reef Research Centre, Department of Science and Technology, Kavaratti- 682555, Union Territory of Lakshadweep, India b Research Centre and Post-Graduate Department of Aquaculture & Fishery Microbiology, MES Ponnani College, University of Calicut, Ponnani, 679 586, Kerala, India c Present Address: School of Ocean Science and Technology, Kerala University of Fisheries and Ocean Studies, Panangad, Kochi 682506 , Kerala, India, [email protected] [ E. Mail: [email protected] ] Received 15 May 2014; revised 11 November 2016 Distribution pattern and community structure of Sea cucumber (Class: Holothuroidea) was investigated in different biogeographic region of three atolls of Agatti, Kavaratti, Kalpeni islands of Lakshadweep archipelago. Holothuria atra and H. leucospilota were randomly distributed in Agatti atoll while they showed aggregated distribution pattern in Kavaratti and Kalpeni atolls.. Species richness in Agatti (1.61 ± 0.46) and Kalpeni (1.63 ± 0.82) atolls were comparable and a lower species richness was observed in Kavaratti (1.33 ± 0.42) atoll. Species diversity of Kalpeni (2.1 ± 0.72) was higher than Agatti (2.0 ± 0.57) and Kavaratti (1.6 ± 0.49). The community structure of Sea cucumber in different biogeographic regions of the reef (WSB- Western Sea grass bed, WSA- Western Sandy area, WRF- Western Reef flat, ORS-Outer reef slop, ERS- Eastern Rocky area, ESW- Eastern Seaweed area) differs significantly (P<0.001). [Key words: Sea cucumber; Kalpeni; Kavaratti; Agatti; Lakshadweep] Introduction Comprehensive studies on holothurians In the seas around India nearly 200 are essential due to their significant role in the species of holothurians are known, of which about maintenance of the marine environment9. No 75 species are from the shallow waters of these attempts have so far been made to understand the only a dozen species are commercially important1. distribution pattern or quantitative estimation of The holothurians chiefly live in the lagoon and the holothurians resources of Lakshadweep10. The many species live in coral reefs of the present study aimed to bring about scientific data Lakshadweep2. James3 gave a general account on in phase regarding distribution, occurrence and ecology of intertidal holothurians from the Indian quantitative estimation of the holothurian region. The occurrence of holothurians resources resources of Lakshadweep based on the different of the Lakshadweep have been studied in greater biogeographic regions of the reef (WSB- Western detail after conducting a planned survey to all the Sea grass bed, WSA- Western Sandy area, WRF- 10 islands in the Lakshadweep4,5, however studies Western Reef flat, ORS-Outer reef slop, ERS- specific to the quantitative descriptions especially Eastern Rocky area, ESW- Eastern Seaweed area) richness and diversity are totally lacking. Recent and to predict the regions of holothurians attempts on sea cumbers of Indian waters are biodiversity by comparing the richness of the limited to the larval rearing and observation of selected zone. juveniles from east coast of India6,7,8. 570 INDIAN J. MAR. SCI., VOL. 46, NO. 03, MARCH 2017 Materials and Methods Density of species was calculated from Lakshadweep is an archipelago in the 50m×5m of each belt transect assuming complete Arabian Sea (8o & 12o 30' N, 71o & 74o E) off the detection of individuals, and averaged over the west cost of India (Figure 1). Lakshadweep replicates. Mean density of each species in the waters harbour rich faunal diversity of vertebrates different zones was then estimated from the and invertebrates11. Present study extended to the transect densities for each atoll. reefs of three atolls of Lakshadweep Archipelago, namely: (1) Agatti (10°51′N 72°11′E) with lagoon area of 17.5 km2; (2) Kavaratti (10°33′N 72°36′E) with lagoon area of 4.96 km2 and (3) Kalpeni (10°4′N 73°38′E) with lagoon area of 25.6 km2 (Fig.2). A total of 72 belt transects12 were surveyed in the atolls covering different geomorphologic zones of Kavaratti, Agatti and Kalpeni islands. Each transect, 50m × 5 m wide, were marked by recording their GPS locations at the start and end points. Direct search method was used to record the occurrence and abundance of Holothurians, at depths ranging from 1m to 30m with the help of snorkeling and SCUBA diving with simultaneous recording by photography, along the belt transects. Sample specimen of each species were collected and identified following standard references1,10. Fig. 1- Map of Lakshadweep Archipelago. Map not to the scale 2a 2b 2c Fig. 2-Atolls Selected for the study. 2a- Agatti, 2b- Kavaratti and 2c- Kalpeni. Source: - Centre for Earth science. Independent sample t-tests were performed Kavaratti and Kalpeni atolls. Aggregation patterns to test the significance of variation in species of different species were analysed from the mean to densities between different zones of Agatti, variance ratios of densities, and tested for any trend K. & SURESHKUMAR: DISTRIBUTION AND COMMUNITY STRUCTURE OF SEA CUCUMBERS IN LAKSHADWEEP 571 towards clumping or uniformity through Chi square regions of the reef were also worked out. H. atra test of significance using the software Biodiversity- was the abundant (16.00±7.2) species while Pro13. Bray-Curtis similarity method was used to Stichopus herrmanni demonstrated sparse evaluate the distance or similarities in abundance of occurrence (0.33±0.58). Species richness and holothurians in different biogeographic region of diversity index were estimated and compared the atolls. Non metric multidimensional scaling was between the different biogeographic regions of also adopted to find a configuration of points in three atolls (Table 2). The community structure of Euclidean space between the Biogeographic region Sea cucumber in different biogeographic regions of and similarity abundance of the holothurians. Mean the reef (Sea grass bed, Sandy area, Reef flat, outer densities in different Biogeographic region were reef slop, Rocky and rubble area and Sea weed and compared through one-way ANOVA with post hoc algae quarter) differs significantly (P<0.05) . Newman–Keuls test. Species richness in Agatti with Kalpeni atoll exhibit more or less comparable (1.61 ± 0.46) and (1.63 ± Results 0.82) respectively and in Kavaratti species richness During the survey fifteen species of Sea found low (1.33 ± 0.42), when compared with cucumbers belong to seven genera and three Agatti and Kalpeni atoll. Species diversity of families were recorded and their distribution pattern Kalpeni (2.1 ± 0.72) was higher than Agatti (2 ± and densities in different substrata were worked 0.57) and Kavaratti (1.6 ± 0.49). out. Average abundance of Sea cucumber (number per 100 m2) along the different biogeographic Table 1:- Occurrence and average abundance (number of Sea cucumber per 100 m2 ± SD) along the different biogeographic regions of the reef of Lakshadweep atolls. WSB- Western Sea grass bed, WSA- Western Sandy area, WRF- Western Reef flat, ORS-Outer reef slop, ERS- Eastern Rocky area, ESW- Eastern Seaweed area Species WSB WSA WRF ORS ERA ESW Holothuria atra Jaeger, 1833 16.00±7.20 3.67±0.58 8.96±0.58 2.33±0.58 10.33±1.5 3.67±1.53 Holothuria leucospilota (Brandt, 1835) 0 0 0 1.00±00 8.67±4.16 1.67±0.58 Holothuria scabra Jaeger, 1833 0 4.67±3.06 1.56±0.58 0.67±0.58 0.33±0.58 0.33±0.58 Holothuria nobilis (Selenka, 1867) 0 0 0 2.00±00 0.67±0.58 0 Holothuria hilla Lesson, 1830 1.67±0.58 0 0.75±0.58 0 5.67±2..08 1.00±1.73 Holothuria pervicax Selenka 1867 0 0 0 0 0.67±0.58 0 Holothuria edulis Lesson, 1830 0 0 0 0.33±0.58 0.67±0.58 0 Holothuria cinerascens (Brandt, 1835) 0 0 0 0 0.67±0.58 0.33±0.58 Actinopyga mauritiana (Quoy & Gaimard, 1834) 0 0 0 0 2.00±00 6.00±20 Bohadschia argus Jaeger, 1833 1.33±0.58 0.33±0.58 0.75±0.58 0 0 0.33±0.58 Synapta maculata (Chamisso & Eysenhardt, 1821) 4 0 2.22±0.58 0 0.67±1.15 0 Pearsonothuria graeffei (Semper, 1868) 0 0 0 3.33±0.58 0 0 Thelenota ananas (Jaeger, 1833) 0 0.33±0.58 0.11±0.58 2.33±0.58 0 0 Stichopus chloronotus Brandt 1835 0.67±1.15 0 0.61±2.31 0 0 0 Stichopus herrmanni Semper, 1868 0 0 0 0 0 0.33±0.58 H. atra found to be distributed in all the were fairly common in different atolls of the selected biogeographic regions of the atolls while archipelago (Table 1). Distribution pattern of Sea Pearsonothuria graeffei restrict their distribution to cucumbers along different atolls showed dissimilar outer reef slope. Species like Holothuria pervicax, pattern, Holothuria atra and H. leucospilota were H. edulis, Thelenota ananas and Stichopus distributed at random in Agatti while they, showed herrmanni were rarely encountered. Bohadschia aggregated distribution pattern in Kavaratti and argus, Holothuria scabra, H. nobilis, H. hilla and Kalpeni. Actinopyga mauritiana and Stichopus herrmanni occurred moderately while Pearsonothuria graeffei exhibited aggregation Actinopyga mauritiana, H. atra, H. leucospilota 572 INDIAN J. MAR. SCI., VOL. 46, NO. 03, MARCH 2017 pattern in all the selected atolls of the study (Table cucumbers can well be ascertained from the MDS 3). plot. Substantiating the cluster analysis, Hierarchical Cluster analysis was aggregation of similar biogeographic zones of performed to find the similarities in different different atolls, with respect to distribution of sea Biogeographic region with respect to the cucumbers were observed in the MDS plot also distribution of sea cucumbers and similarities in (Fig.

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