Statistical Evidence for Three classes of Gamma-ray Bursts

Two different multivariate clustering techniques, the K-means partitioning method and the Dirichlet process of mixture modeling, have been applied to the BATSE Gamma-ray burst (GRB) catalog, to obtain the optimum number of coherent groups. In the standard paradigm, GRB are classified in only two groups, the long and short bursts. However, for both the clustering techniques, the optimal number of classes was found to be three, a result which is consistent with previous statistical analysis. In this classification, the long bursts are further divided into two groups which are primarily differentiated by their total fluence and duration and hence are named low and high fluence GRB. Analysis of GRB with known red-shifts and spectral parameters suggests that low fluence GRB have nearly constant isotropic energy output of 10^{52} ergs while for the high fluence ones, the energy output ranges from 10^{52} to 10^{54} ergs. It is speculated that the three kinds of GRBs reflect three different origins: mergers of neutron star systems, mergers between white dwarfs and neutron stars, and collapse of massive stars.Comment: 7 pages, accepted for publication in the Astrophysical Journal. Minor editorial change

Baseline information of reproduction parameters of an amphidromous croaker Johnius coitor (Hamilton, 1822) from Ganga river basin, India with special reference to potential influence of climatic variability

Reproductive biology of female amphidromous croaker Johnius coitor (Hamilton, 1822) was studied for the first time from various freshwater stretches of Ganga river basin, India in relation to climatic variability. The species showed high spatial variation in reproductive phenology and capable of breeding during pre-monsoon, monsoon, post-monsoon and winter. Water temperature is the most crucial environmental parameter influencing gonadal maturation and breeding. Generalized additive model (GAM) models revealed water temperature near 23–25 °C as optimum and threshold GSI above 3 units necessary for breeding. Pre-spawning fitness (Kspawn50) and size at 50% maturity (LM50) benchmarked through Kaplan-Meier survival fit estimates were in the range 1.27–1.37 units and 19–24.5 cm respectively. First maturity of females was encountered at 11.4 cm within the size range 7.2–28.5 cm. Egg parameters in mature-ripe females ranged between 0.29–0.80 mm (diameter), 0.05–0.19 mg (weight) and 5687–121 849 eggs (absolute fecundity). Mapping of climate preferendum through LOESS smoothing technique hinted water temperatures 32 °C to be detrimental for attainment of pre-spawning fitness while no dependence on rainfall was observed. Based on the climato-hydrological influence on breeding and regional trends of changing climate along river Ganga, we infer minimal climate driven changes in breeding phenology of this amphidromous fish species. Results of this study may serve as baseline information for future studies assessing climate driven changes and evolutionary adaptations in croakers from river Ganga

Assessing vulnerability of freshwater minnows in the Gangetic floodplains of India for conservation and management: Anthropogenic or climatic change risk?

Not AvailableMinnows are the most ignored yet indispensable group of freshwater fishes in Asian inland waters. The reproductive resilience of minnows facing climatic variability, using a wetland inhabiting species Amblypharyngodon mola (Mola carplets) in lower Indo-Gangetic floodplains, was validated. Results revealed that spawning decision in females (threshold gonadosomatic index 5 units) is neither cued by water temperature nor rainfall. They can maintain pre-spawning fitness (condition factor 1.121.25 units) within a broad temperature (2233 C) and rainfall (0800 mm) window by active feeding, thus no risk of skipped spawning decisions while facing future climatic variabilities. Present breeding phenology (May-December) might have prolonged in the recent decade, especially the tail-end, concomitant with increasingly hot and rainy monsoon (May-August) and warmer post-monsoon months (September-December). Minnows are expected to prosper in a future climatic scenario, contributing to ecosystem balance (algal grazers) and regional food security. Female first maturity ( puberty) was encountered at 4.75.1 cm total length, hinting at a probable increase in the recent decade. Climate-favored prolonged recruitment window, in absence of extreme fishing pressure (currently), might have led to such pattern. However, this state might be temporary and labile. Minnows may soon get altered to earlier puberty (=warning sign of stock collapse) if fishing pressure intensifies under a reproductively favoring climate progression. Threshold body girth for spawning females was estimated at 3.23.4 cm ( + 17% than non-breeding ones). Fishing nets having mesh sizes (=total circumference) at least > 3234 mm will most likely be the key to minnows endurance or survival in the coming decades

A Modeling Approach to Determine the Harvest Potential for Sustainable Fishery in Stocked Reservoirs

Not AvailableIndia is bestowed with rich inland water resources ? viz. ponds, lakes & reservoirs, and rivers among others. Inland fish production ? especially from reservoirs - over the years has grown steadily contributing much to the nutritional security of the people, poverty alleviation, community development and women empowerment. Recent advancements in modeling offer tremendous scope to determine population harvest from open waters. In reservoirs, fish harvest levels are of paramount importance because they should ensure sustainability of the fisheries and economic viability. Since stocking is resorted to enhance fish production in reservoirs these days, in this paper, a modeling approach has been attempted for sustainable fishery exploitation in stocked reservoirs. Accordingly, a modified Verhulst-Schaefer model that takes into account the impact of stocking of fingerlings in reservoirs on fish population growth ? was applied in one stocked reservoir. Catch/effort and stocking data from Bargi reservoir (Madhya Pradesh, India) was used in model validation and in the estimation of Maximum Sustainable Yield (MSY). The present study not only be helpful to estimate impact, but also to understand how different stocking regimes impact the fish harvest potential at varying levels of efforts for effective fisheries management of reservoirs

Climate and Development

Not AvailableFloodplain wetlands are among the most threatened ecosystems. It is highly vulnerable to climate change, affecting the wetland ecosystem and its associated fisheries. In the face of data deficiency, this article presents an alternative approach to assess the vulnerability of wetland fisheries to climate change. A total of 15 wetlands from a wetland-fisheries-rich area of West Bengal, India, were selected to illustrate the methodology. The proposed method mainly relies on stakeholders? perceptions of the wetland fisheries vulnerability. Elicitation stakeholders? response iteratively screened the indicators of fisheries vulnerability. The hybrid method of index-based vulnerability comprises two types of indicators: climate indicators with long-term quantitative data and stakeholder perceived vulnerability indicators specific to wetland fisheries. The high level of consensus (92%) among respondents provided strong evidence of climate change in last 15 years, which has also been validated through long-term data analysis. The Principal Component Analysis extracted five synthesized vulnerability indicators, explaining 83.35% variability of the original 14 indicators. The wetlands were further grouped according to differential vulnerability for prioritizing the wetlands for strategic planning. Climate change, reduction in species richness and adaptive capacity were the key components responsible for differential vulnerability. The study also revealed some indigenous climate-smart mitigation strategies of wetland fisheries to climate change

International Journal of Biometeorology

Not AvailableThe spawning and well-being of fish in an ecosystem are closely linked to climatic cues, viz., temperature and rainfall. Reduced fitness can affect the reproductive performance and lead to skipped spawning. Benchmarking the threshold fitness required for a fish population to achieve readiness for spawning, and understanding how climatic parameters influence the fitness will aid in predicting the fate of its reproductive success in future climatic conditions. This study determined the threshold condition factor pre-spawning fitness (Kspawn50) at which 50% of the female Channa punctata population can be deemed fit for spawning. The optimal climate within which pre-spawning fitness is attained by this species under Indian climatic conditions was also identified. The study was conducted from June 2015 to September 2016, covering two spawning seasons (June?August) in a Gangetic floodplain wetland of West Bengal, India. The non-parametric Kaplan?Meier method (survival fit) was used for estimation of pre-spawning fitness. ?Ready to spawn? females were classified based on binary coding of the gonadal maturity stages. The thermal and precipitation range within which spawning fitness is achieved was identified by using the locally weighted?smoothing technique. Female C. punctata pre-spawning fitness (Kspawn50) ranged from 1.26 to 1.39 with an estimated median of 1.29 units. Temperatures between 29 and 32?degree Celsius and rainfall above 100?mm were conducive to attaining the requisite pre-spawning fitness in C. punctata. This is the first study benchmarking the pre-spawning fitness and optimal climate for C. punctata. Understanding spawning requirements can inform the climate change induced impacts on reproductive plasticity and evolutionary adaptations of snakeheads in the Ganga river basin

Environmental Science and Pollution Research

Not AvailableThe regional climate has significantly warmed with erratically declining annual rainfall and intensified downpour within a narrower span of monsoon months, which led to an increased trophic state (algae) in most inland waters. Freshwater clupeids vitally control the aquatic food chain by grazing on algae. Despite increasing food availability, IUCN Red List revealed 16 freshwater clupeids with a decreasing population trend. We investigated one such species reproductive dependencies, Gudusia chapra (Indian river shad), in the lower Gangetic drainage (India) under a mixed context of climate change and overfishing. Monthly rainfall ( 60100 mm) and water temperature ( 3132 C) are key breeding cues for females. The regional climate seems inclined to fulfill these through the significant part of the breeding season, and indeed the species has maintained consistent breeding phenology over 20 years. Other breeding thresholds relevant to fishing include size at first maturity ( 6.8 cm; reduced by ~ 2536%) and pre-spawning girth (Girthspawn50 7 cm; first record). Girthspawn50 is a proxy of the minimum mesh size requirement of fishing nets to allow safe passage of gravid females ( + 22% bulged abdomen) and breed. The operational fishing nets (310 cm mesh) probably have been indulged in indiscriminative fishing of gravid females for generations. Under a favorably changing climate and food availability, existing evidence suggests a fishery-induced evolution in regional females (to circumvent such mesh sizes) through earlier maturation/puberty at smaller sizes. It could be an early warning sign of population collapse (smaller females lessening fecundity fewer offspring). Overfishing seemed to be a bigger threat than climate change

Mobile electrophoresis kit for high school students: Scientific practices with innovation

Not AvailableGel electrophoresis (GE) is the most preferred and adapted technique for the separation and identification of biological molecules like proteins/peptides and nucleic acids from diverse types of organisms. All over the world, researchers, educators, and students aspiring to work in biochemistry and molecular biology disciplines use the polyacrylamide gel electrophoresis (PAGE) technique for resolving proteins/nucleic acids for understanding the structure and function of any cell. A simple PAGE technique requires a wide range of chemicals/reagents along with a well-equipped and well-spaced laboratory. We have developed a compact and impeccable mobile electrophoresis kit suitable for any vertically oriented PAGE technique. This comprehensive and portable laboratory set-up provides the complete advantages of safety, cost-efficiency, space management, and utility to the researchers for high-throughput research. All new equipment of the mobile electrophoresis kit is fabricated using inexpensive and off-the-rack components. Overall performance of the mobile kit was verified through a practical exercises executed by high school students with positive outcomes

Spatial characterization of commercial fishing catch rate of <em>Tenualosa Ilisha</em> in Hooghly-Matlah estuary of India: a geostatistical appraisal

2524-2531Geostatistical method, which involved variogram and kriging, was applied to the geo-referenced catch and effort data collated from the logbook of five randomly selected vessels. Variogram analysis unraveled systematic spatial structure of catch rates of the species. No spatial dependence of catch rate was observed beyond the distance of 17.43 km. Kriging method predicted three regions of high, medium and low catch rates. Even though vessels&rsquo; logbook data was criticized for preferential sampling bias, we established here that application of geo-statistical tools to the same became useful in the present study

Not Available

Not AvailableIn river ecosystems, mesohabitat characteristics (i.e. pool, run, riffle, rapids, etc.) act as proximate variables to fish species occurrence. Fish occurrence and mesohabitat data are very often collected independently for different purposes, which invites challenges to characterize the fish species distribution pattern on mesohabitat scale. The present article delineates quantitative assessment of fish occurrence in relation to mesohabitat using secondary data. Middle stretch of the Narmada River of India has been selected for the study. Geographic information system tools have been used for integration of species and mesohabitat data. Nonmetric Multidimensional Scaling, cluster analysis and Analysis of Similarity techniques have been used for similarity analysis. Logistic regression model has been applied for model-based inferences on family-mesohabitat relationship. Two separate mesohabitat types, viz., Pool-Run and Run-Riffle, have been characterized by the fish species occurrence pattern. Dissimilarity of fish species composition between Pool-Run and Run-Riffle was statistically significant (p-value < 0.05). The family-mesohabiat model predicted that the occurrence probability of a fish species was 14.49 times more in the Pool-Run than that in the Run-Riffle. The predictive accuracy of the model was 69.8%.Not Availabl