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Morphological characters and distribution pattern of the snake eel, Bascanichthys deraniyagalai is debatable during the past half-century. Thus, the species is re-described herewith by morphometry, vertebrae, and molecular data. In recent Chilika expedition in India, we have collected 10 specimens and observed a vertebral count dimorphism. The present study distinctly detected two vertebral groups of B. deraniyagalai: first group with 5 predorsal vertebrae, 81–83 preanal vertebrae, 190–196 total vertebrae in females; however, the sex of the second group with 5 predorsal vertebrae, 72–74 preanal vertebrae, 176–178 total vertebrae was not able to confirm. Further, the molecular data of morphologically identified two distinct groups of B. deraniyagalai shows negligible Kimura 2 parameter genetic divergence and cohesive clustering in Neighbor-Joining phylogeny proved to be the two different morphs of the same species. Hence, the present study indicated there might be vertebral count or sexual dimorphism in B. deraniyagalai, which need further sampling and taxonomic revision to unwrap the fact. [ABSTRACT FROM AUTHOR]

Assessing wildlife tourism sustainability in developing countries is crucial, but few studies analyse the sustainability of dolphin-based wildlife tourism in this context. We measure multiple indicators within the human dimensions of wildlife tourism, including tourist visitation numbers, satisfaction, preferences, perceptions, background and specialisation, to ascertain the extent to which the dolphin-watching industry at Chilika Lagoon, in rural India might be considered sustainable. Our methods included participant observation, tourist surveys, and the use of secondary data on visitation over 10 years. We found that the growth rate of tourist visitation over 10 years was beginning to decline. Tourists were mostly inexperienced, and dissatisfied with their dolphin-watching experience. Tourist preferences and perceptions showed useful insights and shortcomings in the way in which the industry was being conducted and managed, and reflected the expectations of non-specialist visitors. Our study highlights drawbacks in the way that wildlife tourism is managed in a rural, developing world context, which draws the sustainability of the dolphin-watching industry in Chilika into question. Future development of an early warning system that addresses combined governance or managerial, social, economic and ecological indicators, and an integrated management plan for conservation and wildlife tourism could contribute to the sustainable management of such industries. [ABSTRACT FROM AUTHOR]

The spatial distribution of the C/N ratios and variations in δ13C and δ15N of suspended particulate matter were used to characterise their source in Asia’s largest brackish water lagoon, Chilika, India. In addition, the significance of re-mineralised nutrients in the primary productivity of the shallow lagoon was also determined through quantification of the subsurface nitrogen uptake conditions at two relatively stable locations in the lagoon. The results indicated that the influence of terrestrial organic matter was the maximum in the northern sector and was relatively limited at the central and southern part of the lagoon.In situ15N uptake experiments (daytime) under biogeochemically stable conditions revealed that the N uptake by phytoplankton ranged between 0.24 and 1.01 mM m−3 h−1during pre-monsoon and post-monsoon seasons. New production and regenerated production in the shallow lagoon was also estimated by calculatingf-ratios (ratio of nitrate assimilation by phytoplankton to total nitrogenous nutrient assimilation, have been estimated), which varied from 0.52 in the post-monsoon to 0.38 in the pre-monsoon. Lowering of thef-ratio from post- to pre-monsoon indicated a dominance of mineralisation over the new production. [ABSTRACT FROM AUTHOR]

Chilika, a lagoon along the east coast of India, is undergoing transformation due to frequent shoreline change near inlet(s). Shoreline change near inlet includes change in position and shape of inlet, inlet channel length, and spit growth/erosion. These variable features of lagoon inlet(s) critically depend on alongshore sediment transport (LST) and discharge (water and sediment) from the lagoon to the sea. The LST and the processes responsible for sand spit growth/erosion, considered as important attributes of inlet stability, are the subject matter of the present investigation and hence the study assumes importance. The study includes integration of observational and modeling framework. Observations include nearshore wave, bathymetry, beach profile, shoreline and sediment grain size of spits while numerical modeling includes simulation of the wave using MIKE 21 Spectral Wave model and LST simulation using LITtoral DRIFT. The results indicate that the predominant wave directions as S and SSE, which induces round the year south to north alongshore transport with significant seasonal variation in magnitude. The estimated LST closely matches with previous studies near Chilika inlet and for other locations along the Odisha coast. Besides temporal variability, the study reveals spatial variability in alongshore transport near Chilika inlet and considers it as one of the important attributes along with northward spit growth for inlet migration/closure/opening. [ABSTRACT FROM AUTHOR]

An effort has been made for the first time in Asia's largest brackish water lagoon, Chilika, to investigate the spatio-temporal variability in primary productivity (PP), bacterial productivity (BP), bacterial abundance (BA), bacterial respiration (BR) and bacterial growth efficiency (BGE) in relation to partial pressure of CO2(pCO2) and CO2air–water flux and the resultant trophic switchover. Annually, PP ranged between 24 and 376 µg C L−1d−1with significantly low values throughout the monsoon (MN), caused by light limitation due to inputs of riverine suspended matter. On the contrary, BP and BR ranged from 11.5 to 186.3 µg C L−1d−1and from 14.1 to 389.4 µg C L−1d−1, respectively, with exceptionally higher values during MN. A wide spatial and temporal variation in the lagoon trophic status was apparent from BP/PP (0.05–6.4) and PP/BR (0.10–18.2) ratios. The seasonal shift in net pelagic production from autotrophy to heterotrophy due to terrestrial organic matter inputs via rivers, enhanced the bacterial metabolism during the MN, as evident from the highpCO2(10,134 µatm) and CO2air–water flux (714 mm m−2d−1). Large variability in BGE and BP/PP ratios especially during MN led to high bacteria-mediated carbon fluxes which was evident from significantly high bacterial carbon demand (BCD >100% of PP) during this season. This suggested that the net amount of organic carbon (either dissolved or particulate form) synthesized by primary producers in the lagoon was not sufficient to satisfy the bacterial carbon requirements. Lagoon sustained low to moderate autotrophic–heterotrophic coupling with annual mean BCD of 231% relative to the primary production, which depicted that bacterioplankton are the mainstay of the lagoon biogeochemical cycles and principal players that bring changes in trophic status. Study disclosed that the high CO2supersaturation and oxygen undersaturation during MN was attributed to the increased heterotrophic respiration (in excess of PP) fuelled by allochthonous organic matter. On a spatial scale, lagoon sectors such as south sector, central sector and outer channel recorded “net autotrophic,” while the northern sector showed “net heterotrophic” throughout the study period. [ABSTRACT FROM PUBLISHER]

A study was conducted in Lakshadweep islands to determine the feasibility of using Indian Remote Sensing (IRS) satellites for detecting changes in the seagrass from other coastal features. IRS ID and IRS P6 LISS III having spatial resolution of 23.5 m with lower cost compared to all other contemporary satellites with the same spatial resolution have not been widely used for monitoring the changes in seagrass cover. In this context, the present study attempted to explore the effectiveness of LISS III data for mapping seagrasses and to inform the international community about the usefulness of these low-cost imageries for coastal resource monitoring. Supervised classification and change detection studies found a significant decrease in seagrass cover of 73.03 ha in the Lakshadweep group of islands. An overall accuracy of 67.5% was obtained for the change maps, and seagrass cover and its changes vary at different islands. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

The northeasterly long shore transport (littoral drift) along the east coast of India shifts the mouth of the lagoon northeastwards. It results in lengthening of the outer channel, reduced tidal flux, fall in salinity levels, weed infestation, decline in fishery resources, and overall loss of biodiversity and productivity. The Chilika Development Authority made an artificial mouth near the village of Sipakuda, which was opened on 23 September 2000. The present study focuses on applications of Resourcesat-1 LISS-III and AWiFS data to understand the impact of the new mouth opening on the morphology and water quality of the Chilika Lagoon. Digital image processing of multi-temporal Resourcesat-1 AWiFS, LISS-III, and IRS-1D LISS-III data was carried out. Changes were shown out for pre- and post-opening of the new mouth. The results indicate that the initial cut of 80 m has widened to approximately 676 m and, so far, the process has not attained stability. There has been northward erosion for approximately 376 m and southward erosion for approximately 143 m at the new mouth. The study shows that the strong ebbing tide current from the northwest is responsible for this erosion. The old mouth has been closed completely just three years after the opening of the new mouth. There has been an overall rise in salinity levels in the Chilika Lagoon, in particular during the pre-monsoon period following the opening of the new mouth. This indicates that the tidal flux in the lagoon has increased and the associated circulation is effective in mixing the water masses. After the opening of the new mouth, weeds have reduced by a 172-km2 area, in particular in the northeast part of the lagoon. AWiFS data is extremely useful in identifying changes in morphology and water quality under different tide conditions. Tidal conditions influence the signatures of turbidity, weed cover, shoals, and spits under development. The SWIR channel of AWiFS is found to be extremely useful for detecting aquatic vegetation. The study concludes that large transport of sediments at the new mouth opening, along with predominant erosion of the northern bank, suggests a northward migration of the new mouth in the near future. [ABSTRACT FROM AUTHOR]

Four species of mysids collected from the Minicoy lagoon are reported. Anisomysis minicoyensis sp. nov. is distinguished from the related species by the shape of the rostrum, the relative length of the antennal scale and the short protuberances on the second segment of the mandibular palp. The other three species recorded are Siriella australiensis , Anisomysis truncata and unidentified species of subfamily Gastrosaccinae. [ABSTRACT FROM AUTHOR]

Sedimentation, resulting from cyclic growth, spread and disintegration of macrophytes and influx of silt-laden fresh water through the riverine system, is the dominant process influencing the contemporary phase of lagoon modification in the Chilka. Remote sensing offers promise in the detection and delineation of the functional elements of lagoon modification. Therefore, IRS-1B LISS-I data along with synchronous ground data observations have been used in the present study for a qualitative and quantitative evaluation of the components involved in the modification and to obtain estimates of their distribution, abundance, diversity and physical state during an annual cycle. Results obtained indicate that the ecological parameters in the lagoon such as water quality and macrophytes undergo significant seasonal as well as interannual variability following interannual monsoon variability. Seasonal mode of variability appears to dominate over interannual mode. October and April appear as two extreme periods in the annual cycle of lagoon modification. Maximum likelihood classification for digital image analysis of time series data depicts the different lagoonal features, which largely agree with field observations. Area estimates for spectrally significant classes and their comparison with earlier studies indicate that the rate at which the vegetation is spreading has been increasing steadily and alarmingly. IRS data proved useful for predicting selected water quality parameters. [ABSTRACT FROM AUTHOR]