Research papers

WILLIAMS SUZANNE, APTE, D.A, OZAWA TOMOWO, KALIGIS FONTJE, NAKANO TOMOYUKI (2010)

Speciation and dispersal along continental coastlines and island arcs in the Indo-West Pacific turbinid gastropod genus Lunella. Evolution, 65-6: 1752–1771.

Abstract: Species trees were produced for the Indo-West Pacific (IWP) gastropod genus Lunella using MrBayes, BEAST, and ∗BEAST with sequence data from four genes. Three fossil records were used to calibrate a molecular clock. Eight cryptic species were recognized using statistical methods for species delimitation in combination with morphological differences. However, our results suggest caution in interpreting ESUs defined solely by the general mixed Yule Coalescent model in genera like Lunella, with lower dispersal abilities. Four almost entirely allopatric species groups were recovered that differ in ecology and distribution. Three groups occur predominantly along continental coastlines and one occurs on island arrays. Sympatric species occur only in the torquata and coronata groups along coastlines, whereas species in the cinerea group, distributed in two-dimensional island arrays, occur in complete allopatry. Dispersal along island arcs has been important in the maintenance of species distributions and gene flow among populations in the cinerea group. The emergence of new islands and their eventual subsidence over geological time has had important consequences for the isolation of populations and the eventual rise of new species in Lunella.

APTE, D.A. & SUTIRTHA DUTTA (2010)

Ecological determinants and stochastic fluctuations of Tridacna maxima survival rate in Lakshadweep Archipelago. Systematic and Biodiversity, 8 (4): 461-469.

Abstract: Compounding effects of slow life-history traits and adult-specific overharvesting have caused a range-wide decline of several giant clam populations. Erratic changes in these populations reported at isolated reefs, are attributable to stochastic fluctuations in recruitment and survival rates. These population rate parameters may be adversely influenced by the considerable and increasing human–reef economic interactions in tropical waters. The unsubstantiated knowledge on such influences hinders conservation management of species-habitat linkages particularly for species like the small giant clam (Tridacna maxima). Our study reports small giant clam survival rate, its ecological determinants and stochastic fluctuations from shallow lagoon waters of Lakshadweep Archipelago; a natural habitat not subjected to commercial giant clam harvesting. Survival rate was estimated by monitoring the status of identified individuals in belt-transects through successive years 2005–2009. The role of different factors in explaining the variation in survival rates was investigated at relevant scales: anthropogenic pressure at the population level in the reef, clam density at sub-population level in the belt-transects, and variables related to clams at the individual level. Effects were quantified through univariate regression techniques and Kaplan–Meier estimator coupled with generalized linear (logit link) models. Small giant clam survival rate in the reef decreased and its spatio-temporal fluctuations increased along the increasing gradient of human populations. Survival was density-independent. Size/age specific survival followed Siler distribution characterized by very low early-age survival, increased adult-age survival, and low older-age survival. Anchorage in coral substrate exerted a curvilinear effect, where survival of moderately anchored clams > loosely anchored clams >> deeply embedded clams. Our study recommends regular population monitoring in densely inhabited islands to detect incipient changes, which can subsequently be confronted by scientific lagoon bed management.

 

 

APTE, D.A. et al (2010)

Monitoring Densities of the Giant Clam Tridacna maxima Populations in the Lakshadweep Archipelago, India. Marine Biodiversity Records, Cambridge UK. Doi:10,1017/S1755267210000680; vol 3; e78; 2010, 1-9.

Abstract: Giant clams are endangered in many parts of their Indo-Pacific range owing to adult specific overharvesting that threatens recruitment, a demographic parameter exhibiting high sensitivity to environmental disturbances and adult densities among tridacnids. Lakshadweep reefs are not subjected to commercial giant clam fishery, and population assessment has not been carried out in these waters so far. We monitored the small giant clam Tridacna maxima populations in confined waters of 12 reefs in Lakshadweep Archipelago during 2005–2007 using a systematic line transect based distance sampling framework. Overall T. maxima density in the Archipelago was estimated at 141.2/ha (95% CL 118.2–168.7) in 2005 and 122.7/ha (103.60–145.37) in 2006. Populations showed wide variation in densities and relative proportions of different age-classes between reefs. While Agatti, Bitra and Chetlat lagoons harboured high clam densities, Amini harboured the most impoverished population. Data simulation showed that total clam count along transects of 100 m length × 2–5 m strip width, in a minimum of 140 replicates, stratified by area among lagoons, would provide a viable monitoring index for rapid assessments of T. maxima in Lakshadweep. Compared to unbiased absolute abundance estimates, this monitoring index could be achieved more easily, without much compromise on accuracy and precision, necessary for meaningful spatio-temporal comparisons. (Download pdf)

Attachments:
Download this file (Giant Clam.JMBA.Apte et al.pdf)Giant Clam Densities[ ]308 Kb

APTE, D.A. et al (2010)

An Annotated and illustrated Checklist of the Opisthobranch fauna of Gulf of Kutch, Gujarat, India with 20 new records for Gujarat and 14 new records for India. Part 1. Journal of Bombay Natural History Society, 107 (1), 14-23.

Abstract: The Opisthobranch fauna of Gujarat is among the least studied molluscs. Field surveys were undertaken along the Gulf of Kutch over a period of four months under the All India Co-ordinated Project on Taxonomy (AICOPTAX – Mollusca) funded by the Ministry of Environment and Forests, Government of India, and supported by the Gujarat State Forest Department and Marine National Park authorities. 33 species belonging to 19 families were recorded, of which 21 are new records to Gujarat and 13 are new records to Indian coast. (Download pdf)

Attachments:
Download this file (Opisthobranch_Gujarat_Part 1.pdf)Opisthobranch Fauna of Gulf of Kutch[ ]492 Kb

APTE, D.A. (2009)

Opisthobranch fauna of Lakshadweep Islands, India with 54 new records to Lakshadweep and 40 new records to India. Journal of Bombay Natural History Society. 106(2), 162-175.

Abstract: Opisthobranchs are the least studied fauna of India. The present study was carried out in Lakshadweep Archipelago between 2005 and 2009. During the 4-year study a total of 60 species from 25 families were recorded. Of these 60 species, 52 are new records to Lakshadweep and 40 are new records to the Indian coast. (Download pdf)

Opisthobranch fauna of Lakshadweep Islands, India with 54 new records to Lakshadweep and 40 new records to India. Journal of Bombay Natural History Society. 106(2), 162-175.

 

Abstract: Opisthobranchs are the least studied fauna of India. The present study was carried out in Lakshadweep Archipelago between 2005 and 2009. During the 4-year study a total of 60 species from 25 families were recorded. Of these 60 species, 52 are new records to Lakshadweep and 40 are new records to the Indian coast. (Downlode pdf)
More Articles...

book1

Share it

Latest Projects


Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Latest publications


Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109

Warning: Creating default object from empty value in /home/deepakap/public_html/modules/mod_latestnews/helper.php on line 109