Effect of climato-environmental parameters on chlorophyll a concentration in the lower Ganga basin, India / Efecto de los parámetros climáticos ambientales sobre la concentración de clorofila a en la cuenca baja del Ganges, India

Introduction: Chlorophyll a concentration proxies the phytoplankton biomass which directly involves in signifying the production functions of aquatic ecosystem. Thus, it is imperative to understand their spatio-temporal kinetics in lotic environment with reference to regional climatic variabilities in the tropical inland waters. Objective: In-situ studies were conducted to examine the changes in phytoplankton biomass in lower Ganga basin as influenced by various environmental parameters under regional climatic variability during 2014-2016. Methods: Firstly, the most key influential environmental parameters on riverine Chl-a concentration were determined. Then the direct cascading effect of changing climatic variables on key environmental parameters were derived through modeling and quantified probable changes in mean Chl-a concentration in the lower stretch of river. Results: Only five environmental parameters namely water temperature, total dissolved solid, salinity, total alkalinity and pH were key factors influencing Chl-a (Multiple R2: 0.638, P < 0.05). Present estimates indicate that if the present rate of regional climatic variability over the last 3 decades (mean air temperature + 0.24 °C, total annual rainfall -196.3 mm) remain consistent over the next three decades (2015-2045), an increase in mean Chl-a by + 170 µgL-1 may likely be expected grossly reaching about 475.94 µg L-1 by the year 2045 or more. Conclusions: The present study is first such comprehending a gross hint towards the probable ecosystem response with an alternative model based methodology in data-deficient situations. Subsequently, the output would also be of great benefit for increase water governance and developing strategy protocol for sustainable water management for greater ecosystem services.

Introducción: La concentración de clorofila a representa la biomasa de fitoplancton la cual influye directamente en las funciones de producción de los ecosistemas acuáticos. Por lo tanto, es imperativo comprender su cinética espacio-temporal en el ambiente lótico con respecto a las variabilidades climáticas regionales en las aguas continentales tropicales. Objetivo: Se realizaron estudios in situ para examinar la influencia de varios parámetros ambientales en la biomasa del fitoplancton en la cuenca baja del Ganges durante 2014-2016. Métodos: En primer lugar, se determinaron los parámetros ambientales más influyentes en la concentración de Chl-a fluvial. Luego, el efecto directo en cascada de las variables climáticas sobre los parámetros ambientales clave, mediante el modelado y los cambios en la concentración media de Chl-a en el tramo inferior del río. Resultados: Solo cinco parámetros ambientales, entre ellos, temperatura del agua, sólidos disueltos totales, salinidad, alcalinidad total y pH, fueron factores clave que influyeron en la Chl-a (R2 múltiple: 0.638, P < 0.05). Las estimaciones actuales indican que si la tasa actual de variabilidad climática regional durante las últimas 3 décadas (temperatura media del aire + 0.24 °C, precipitación total anual -196.3 mm) permanece constante durante las próximas tres décadas (2015-2045), se presente un aumento en el promedio de la Chl-a en +170 µgL-1 y alcance aproximadamente 475.94 µgL-1 para el 2045 o más. Conclusiones: Este estudio presenta una metodología basada en modelos alternativos en situaciones de escasez de datos, la información generada también podría contribuir a mejorar la gobernanza del agua y a desarrollar un protocolo para la gestión sostenible del agua y de esta manera mejorar los servicios ecosistémicos.

Using otolith weight to predict the age of different stocks of Sperata aor (Siluriformes: Bagridae) from the River Ganga

Estimation of accurate fish age is considered as an essential step for the understanding of life history characteristics, population dynamics, and the management of the fisheries resources. The otolith weight keeps on increasing because of continuous deposition of material on the otolith surface; therefore, otolith measurements are successfully used to infer fish age. The present study was conducted to estimate the relationship between otolith weight and observed age (estimated by counting annuli on the sectioned otoliths) for the stocks of Sperata aor. A total of 315 samples were collected from January 2016 to April 2017 from three different stocks of S. aor i.e. Narora-Kanpur, Varanasi and Bhagalpur from the River Ganga. Linear regression analysis was applied between otolith weight and observed age to predict the age of the fish of each stock from otolith weight. Significant relationships between otolith weight and fish age were observed for the three stocks of the selected fish species from the River Ganga (R2 > 0.9, P 0.05). Overall, 88.5, 88.8, and 87.2 % of the predicted ages were correctly classified to their observed ages for Narora-Kanpur, Varanasi, and Bhagalpur stock, respectively. Thus, it can be concluded that the relationship between otolith weight and fish age can provide a surrogate method of age estimation, and can be used to examine the age structure of the three stocks of S. aor from the River Ganga.

La estimación precisa de la edad de peces es considerada un paso esencial para la evaluación de su historia natural, dinámica de población y manejo de pesquerías. El otolito sigue creciendo debido a la continua deposición de material en la superficie; por lo tanto, las medidas del otolito son un buen indicador para inferir la edad del pez. En este estudio se evaluó la relación entre el peso de los otolitos y la edad observada (estimada contando los anillos de los otolitos seleccionados) de individuos de Sperata aor. En total se recolectaron 315 muestras entre enero 2016 y abril 2017 en tres zonas de S. aor en el Río Ganga (Narora-Kanpur, Varanasi y Bhagalpur). Se aplicó un análisis de regresión lineal entre el peso de los otolitos y la edad observada para predecir la edad de los peces de cada zona a partir del peso de los otolitos. Se observaron relaciones significativas entre el peso de los otolitos y la edad de los peces de las zonas del Río Ganga (R2 > 0.9, P 0.05). En general, 88.5, 88.8 y 87.2% de las edades predichas se clasificaron correctamente con respecto a las edades observadas para Narora-Kanpur, Varanasi y Bhagalpur, respectivamente. Se puede concluir que la relación entre el peso de los otolitos y la edad de los peces puede proveer un método para la estimación de la edad y puede ser usado para examinar la estructura de edades en tres stocks de S. aor en el Río Ganga.

Analysis of water quality parameters of River Ganga during Maha Kumbha, Haridwar, India.

This study represents the summary of the water quality of River Ganga during mass bathing in Haridwar during Maha Kumbha of 2010 in terms of microbiological and molecular analysis. The sample was collected from River Ganga during Makar Sankranti to Shakh Poornima and assessed for fecal indicator bacteria Escherichia coli along with Standard Plate Count (SPC) to determine total bacterial load in the river. Of all the nine days of sample collection (mass bathing days) results on the main royal bath (Baisakhi) displayed maximum SPC (log 6.79 cfu ml-1) and most probable number (210 and 150 MPN 100 ml-1 for total and fecal coli form, respectively). The water was extremely contaminated and not suitable for drinking on Somvati Amavasya, Maghi Poornima, Maha Shivratri and Baisakhi. The results clearly indicated that the mass bathing coupled with ritual activities performed by bathers was most probable cause of increased values of different parameters. The polymerase chain reaction analysis targeting malate dehydrogenase (mdh) gene proved to be more rapid and sensitive than classical culture techniques.

Studies on chemical composition and energy transformation in river Ganga at Kanpur and Varanasi due to environmental degradation.

Impact of effluents discharged in Ganga through various sources on chemical composition, energy transformation rate and level of heavy metals was studied at Kanpur and Varanasi. The effluents were found to be nil in oxygen with acidic in oxygen with acidic to neutral pH (6.8-7.0) and having very high values of free CO2 (40-68 mg l-1), alkalinity (300.0-412.0 mg l-1), conductance (1082.0-1824.0 μmhos), total dissolved solids (542.0-912.0 mg l-1), hardness (228.0-330.0 mg l-1), chloride (42.0-60.0 mg l-1), organic matter (8.4-18.2 mg l-1) and BOD load (98.0-248.0 mg l-1). The heavy metals Cu, Cr, Cd, Pb and Zn were also quite high in the effluents (48.6-78.4, 54.0-84.6, 9.8-12.4, 72.4-84.0 and 148.6-284.0 μg l-1 respectively). The discharged effluents induced severe reduction in oxygen (av. 0.82-3.4 mg l-1) and sharp increase in the level of free CO2 (av. 10.8-24.8 mg l-1), alkalinity (182.4-288.4 mg l-1), conductance (480.0- 628.0 mmhos), total dissolved solids (254.0-315.0 mg l-1), hardness (170.0-259.0 mg l-1), chloride (36.0-52.0 mg l-1), organic matter (4.8-6.8 mg l-1) and BOD load (36.4- 58.4 mg l-1) at the discharge point (OF zones) from their comparatively much lower values before discharge (AOF zone). The rate of energy transformation and photosynthetic efficiency also reduced considerably at the discharge point (av. 1060-2101 calm-2day-1 and 0.09-0.18%) from high values before discharged point (av. 4045-4733 calm-2day-1 and 0.34-0.42%). The level of Cu, Cr, Cd, Pb and Zn also showed higher values at the discharged point (20.4-38.0, 22.4-54.8, 5.2-7.8, 30.8-72.0 and 64.8-120.8 μg l-1 respectively). Considerable improvement was observed below the discharge (BOF zone). Comparison with earlier observation revealed that the magnitude of impact has reduced considerably after the regulation in the discharge both in he respect of chemical composition and energy transformation rates.