Biodiversity and monthly density fluctuations of water mites in Khankra gad, a spring-fed tributary of river Alaknanda, Pauri Garhwal in Uttarakhand, India

Hydrachnidia is an important group of aquatic invertebrates. They play an important role in regulating other invertebrate populations, thus influencing the composition and functionality of river ecosystems. The present study aims to assess the habitat ecology, density and diversity of aquatic mites in the Khankra gad, Rudraprayag district for a period of two year on a monthly basis, from July 2018 to June 2020. The Khankra gad is a perennial spring-fed stream originating from the Bansoun peak in district-Rudraprayag of Garhwal Himalaya (800 m asl). A total of 2537 Hydrachnidia samples were collected, belonging to 6 families viz, Torrenticolidae, Sperchontidae, Feltriidae, Hygrobatidae, Lebertiidae and Aturidae. Sperchontidae, Torrenticolidae and Hygrobatidae were the common families recorded in both spots, whereas Feltriidae was recorded in Spot-1, Lebertiidae and Aturidae were recorded in Spot-2. The highest numbers (1842) of Hydrachnidia were collected from Spot-2.  A total of 19 aquatic mite species were recorded in Spot-1 and 25 species in Spot-2 throughout the study period. Aquatic mites showed maximum density (177 units.m-2 in Spot-1 and 274units.m-2 in Spot-2) in December and minimum (11 units.m-2 in Spot-1 and 17 units.m-2 in Spot-2) in July. Various ecological parameters of our study indicated that Khankra gad is a good habitat for aquatic mites

Age and growth analysis of the fish Mastacembelus armatus (Lacepede) from River Nayar, Garhwal Himalaya, Uttarakhand

The ability to age fish accurately is essential in understanding the dynamics of fish population. Age and growth determination in Mastacembelus armatus was assessed by the scale method which was verified by the length-frequency distribution method. The scales were small, elongated and the focus was shifted slightly uppish from the centre. The fish length and scale radius relationship was found linear (Scale radius = 6.974 + 0.452 Fish length; r = 0.9746) and authenticated the age analysis. Back calculation method was used to find out the size of fish at annulus formation, which confirmed four age rings in M. armatus  at the size of 14.07±0.92,  26.05±4.99,  37.96± 2.59  and  48.48±6.06 cm respectively. First two age rings were observed in the fish length group 30-40 cm, the third ring was observed in 40-50 cm and the fourth ring in 50-60 cm length group. The finding was dully validated by length-frequency distribution method. The growth annual increment (h) of M. armatus shows that the length increment was 14.07, 13.32, 11.91 and 10.52 cm during 1st, 2nd, 3rd and 4th year respectively. It shows that the fish grows continuously during its entire life period. The average growth (? h) was observed as 12.12 cm. annually. The assessment of age and growth rate of fish is a prerequisite to generate the information on recruitment, longevity and fluctuations in fishery caused by various year classes which is an important tool for rational exploitation of fish stock

Population structure and diversity of the periphyton community in the glacier-fed stream Balkhila at Siron from Garhwal Himalaya

The stream Balkhila is a glacier-fed and originates at higher altitudes from the Lal Mati glacier, flows through the famous Mandal valley of Garhwal Himalaya and finally merges with the Alaknanda River in Chamoli district of Uttarakhand. The present study aimed to assess the population structure, density and diversity of the periphyton community along with some detrimental ecological parameters in the glacier fed stream Balkhila for a period of two years on a monthly basis from November 2018 to October 2020. The stream Balkhila was represented by 17 periphytic genera belonging to 3 classes, namely, Bacillariophyceae, Chlorohyceae and Cyanophyceae. The class Bacillariophyceae was represented by 10 periphytic genera (Cymbella, Navicula, Fragilaria, Nitzschia, Ampohora, Diatoma, Synedra, Tabellaria, Cocconeis and  Meridion), and Chlorophyceae (green algae) was represented by 6 algal genera (Chlorella, Ulothrix, Zygnema, Oedogomium, Spirogyra and Stigeoclonium). The class Myxophyceae was represented by a single genus (Phormidium). The maximum periphytic density (individuals/cm2) was found to be 316.7±7.1 x 103 in January, and the minimum density (12.5±3.5 x 103) was recorded in August. The SIMPLER test indicated 18.58% dissimilarity of periphytic communities between the two years of study. The Shannon–Wiener diversity index values were high (2.358 and 2.388) in December and January and minimum (0.2484 and 0.3534) in July and August during the first and second years of the study, respectively. Multivariate canonical correspondence analysis (CCA) suggested that most of the periphytic genera were closely associated with the winter season (December, January and February). The various ecological parameters of our study indicated that the Balkhila stream is a conducive habitat for periphyton communities

Highlighting the Compound Risk of COVID-19 and Environmental Pollutants Using Geospatial Technology

The new COVID-19 coronavirus disease has emerged as a global threat and not just to human health but also the global economy. Due to the pandemic, most countries affected have therefore imposed periods of full or partial lockdowns to restrict community transmission. This has had the welcome but unexpected side effect that existing levels of atmospheric pollutants, particularly in cities, have temporarily declined. As found by several authors, air quality can inherently exacerbate the risks linked to respiratory diseases, including COVID-19. In this study, we explore patterns of air pollution for ten of the most affected countries in the world, in the context of the 2020 development of the COVID-19 pandemic. We find that the concentrations of some of the principal atmospheric pollutants were temporarily reduced during the extensive lockdowns in the spring. Secondly, we show that the seasonality of the atmospheric pollutants is not significantly affected by these temporary changes, indicating that observed variations in COVID-19 conditions are likely to be linked to air quality. On this background, we confirm that air pollution may be a good predictor for the local and national severity of COVID-19 infections.The authors acknowledge financial support from the Spanish Government, Grant RTI2018-354 094336-B-I00 (MCIU/AEI/FEDER, UE), the Spanish Carlos III Health Institute, COV 20/01213, and the Basque Government, Grant IT1207-19

Gyroid-Forming Diblock Copolymers Confined in Cylindrical Geometry: A Case of Extreme Makeover for Domain Morphology

The self-assembly of gyroid-forming diblock copolymers confined in cylindrical geometry is studied using a combination of computer simulations and experiments. The simulations, based on a system qualitatively representative of poly(styrene-b-isoprene), are performed with cylindrical nanopores of different diameter (D) and surface selectivity. The effects of the pore size and surface selectivity on morphology are systematically investigated. Different morphological sequences are predicted for two gyroid-forming diblock copolymers. The experiments are carried out on two gyroid-forming poly(styrene-b-dimethylsiloxane) block copolymer samples confined in the core of continuous core−shell nanofibers of different diameters, which are obtained by a coaxial two-fluid electrospinning technique. The internal microphase-separated morphologies of these fibers are investigated by transmission electron microscopy (TEM). Both simulations and experiments demonstrate that a rich variety of structures spontaneously form for the gyroid-forming diblock copolymers, depending on the conditions of cylindrical confinement. Many of these confinement-induced structures are quite different from those of cylinder-forming or lamella-forming block copolymers. Simulations further show that these structures depend sensitively on the block copolymer composition, surface selectivity, and the ratio D/L0 where L0 is the period of the equilibrium gyroid phase. While the simulation and experimental systems are representative of different chemistries, the morphological predictions of simulations are qualitatively consistent with the experimental observations.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract DAAD-19-02-D-0002)United States. Army Research Offic

Mechanical properties, microstructure and crystallographic texture of magnesium AZ91-D alloy welded by Friction Stir Welding (FSW)

The objective of the study was to characterize the properties of a magnesium alloy welded by friction stir welding (FSW). The results led to a better understanding of the relationship between this process and the microstructure and anisotropic properties of alloy materials. Welding principally leads to a large reduction in grain size in welded zones due to the phenomenon of dynamic recrystallization. The most remarkable observation was that crystallographic textures appeared from a base metal without texture in two zones: the thermo-mechanically affected and stir welded zones. The latter zone has the peculiarity of possessing a marked texture with two components on the basal plane and the pyramidal plane. These characteristics disappeared in the TMAZ, which had only one component following the basal plane. These modifications have been explained by the nature of the plastic deformation in these zones, which occurs at a moderate temperature in the TMAZ and high temperature in the SWZ

DIURNAL VARIATION IN SOME ASPECTS OF LIMNOLOGY OF THE RIVER MANDAKINI FROM THE GARHWAL HIMALAYA

Dissolved O, free Co2, and total alkalinity exhibit a negative relationship with the durinal temperature variation. But pH and oxygen saturation values increase during day and decrease at night. The study also provides an answer as to why the maximum number of fish are caught during night

MATHEMATICAL MODELING OF THE FOOD ITEMS IN THE GUT AND THEIR AVAILABILITY IN THE ENVIRONMENT FOR THE HILL-STREAM FISH, Barilius bendelisis (HAMILTON) BASED ON STRAUSS SELECTIVITY INDEX

Barilius bendelisis (Hamilton) is an ornamental fish. The feeding ethos of fish is of great concern for its culture and breeding. Strauss selectivity index is simply the unweighted difference in proportion (L= ri - pi) of the prey item in the gut and the environment. It ranges from   -1 to + 1 with a positive value indicating preference and the negative value indicating avoidance or inaccessibility. Three length-groups (1 < 5cm, 5-10cm. and > 10cm.) were analyses in current study. Barilius bendelisis has been found to accompany a change of food habit with more emphasis on insect items in higher length groups.  It had been noticed that in Barilius bendelisis feeding ethos showed dipterans larva as more available digestible food part in gut portion than ephemeroptera and trichoptera larvae in all different size groups