Pradipta R. Muduli | Chilika Development Authority (original) (raw)

Papers by Pradipta R. Muduli

Abstract: Spatial distributions of hydrochemical characteristics were studied during three season... more Abstract: Spatial distributions of hydrochemical characteristics were studied during three seasons of 2007 in

Science of The Total Environment, 2021

Spatial and seasonal heterogeneity in phytoplankton communities are governed by many biotic and a... more Spatial and seasonal heterogeneity in phytoplankton communities are governed by many biotic and abiotic drivers. However, the identification of long-term spatial and temporal trends in abiotic drivers, and their interdependencies with the phytoplankton communities' structure is understudied in tropical brackish coastal lagoons. We examined phytoplankton communities' spatiotemporal dynamics from a 5-year dataset (n = 780) collected from 13 sampling stations in Chilika Lagoon, India, where the salinity gradient defined the spatial patterns in environmental variables. Generalized additive models showed a declining trend in phytoplankton biomass, pH, and dissolved PO4 in the lagoon. Hierarchical modelling of species communities revealed that salinity (44.48 ± 28.19%), water temperature (4.37 ± 5.65%), and season (4.27 ± 0.96%) accounted for maximum variation in the phytoplankton composition. Bacillariophyta (Indicator Value (IV): 0.74) and Dinophyta (IV: 0.72) emerged as top indicators for polyhaline regime whereas, Cyanophyta (IV: 0.81), Euglenophyta (IV: 0.79), and Chlorophyta (IV: 0.75) were strong indicators for oligohaline regime. The responses of Dinophyta and Chrysophyta to environmental drivers were much more complex as random effects accounted for ~70-75% variation in their abundances. Prorocentrum minimum (IV: 0.52), Gonyaulax sp. (IV: 0.52), and Alexandrium sp. (IV: 0.51) were potential indicators of P-limitation. Diploneis weissflogii (IV: 0.43), a marine diatom, emerged as a potential indicator of N-limitation. Hierarchical modelling revealed the positive association between Cyanophyta, Chlorophyta, and Euglenophyta whereas, Dinophyta and Chrysophyta showed a negative association with Cyanophyta, Chlorophyta, and Euglenophyta. Landsat 8-Operational Land Imager satellite models predicted the highest and lowest Cyanophyta abundances in northern and southern sectors, respectively, which were in accordance with the near-coincident field-based measurements from the lagoon. This study highlighted the dynamics of phytoplankton communities and their relationships with environmental drivers by separating the signals of habitat filtering and biotic interactions in a monsoon-regulated tropical coastal lagoon.

International Journal of Environmental Science and Technology, 2021

Remote Sensing, 2020

The SARS-CoV-2 (or COVID-19) lockdown in India, which started at an early stage of its infection ... more The SARS-CoV-2 (or COVID-19) lockdown in India, which started at an early stage of its infection curve, has been one of the strictest in the world. Air quality has improved in all urban centers in India, a major emitter of greenhouse gases (GHG). This study is based on the hypothesis that an abrupt halt in all urban activities resulted in a massive decline in NO2 emissions and has also altered coastal nitrogen (N) inputs; in-turn, this affected the trophic status of coastal waters across the country. We present the first evidence of an overall decline in pre-monsoon chlorophyll-a, a proxy for phytoplankton biomass, in coastal waters off urban centers during the peak of the lockdown in April. The preliminary field data and indirect evidence suggests the reduction in coastal chlorophyll-a could be linked to a net decline in nutrient loading, particularly of bioavailable N through watershed fluxes and atmospheric deposition. The preliminary results stress the importance of a further un...

Science of The Total Environment, 2021

Cyclones can produce a wide variety of short-term and long-term ecological impacts on coastal lag... more Cyclones can produce a wide variety of short-term and long-term ecological impacts on coastal lagoons depending on cyclone's physical-meteorological characteristics and the lagoon's geographic, geomorphic, and bathymetric characteristics. Here, we theorized that in monsoon regulated tropical coastal lagoons, another important factor that could determine the impact of a cyclone is the landfall season or time of the year with reference to the monsoon season. We analyzed the impact of two cyclones which made landfall near Chilika, Asia's largest brackish water lagoon in different seasons, Cyclone Fani and Titli before and after the monsoon season. We compared field measured and satellite-derived water quality parameters including nutrient, salinity, water temperature, transparency, Chlorophyll-a (Chl-a), total suspended matter (TSM), and colored dissolved organic matter (CDOM) before and after the cyclones. We found that although both the cyclones were of similar intensities, after their land interaction, their impact on the lagoon's water quality was contrasting. The post-monsoon cyclone produced a substantial increase in total nitrogen (TN) and total phosphorous (TP), a large drop in salinity, CDOM, and Chl-a. In contrast, after the pre-monsoon cyclone, TN and TP did not show any such hike, no substantial change in salinity and CDOM either, and only a slight increase in Chl-a was observed. We found that the controlling factor in determining the impact of a cyclone is the rate and duration of freshwater discharge to the lagoon, which is normally a strong pulse for pre-monsoon and a continued high flow for post-monsoon cyclones. We conclude that the antecedent conditions of the lagoon and the watershed at the time of a cyclone's landfall is a key criterion in determining the impact. The combined use of satellite data and field data was proved critical to capture the overall impact of cyclones on the hydrological characteristics of the monsoon-regulated coastal lagoon.

Marine pollution bulletin, 2018

Bioavailable dissolved organic carbon (B), nitrogen (B) and their degradation rate constants were... more Bioavailable dissolved organic carbon (B), nitrogen (B) and their degradation rate constants were measured for the Chilika Lagoon, India. Long-term laboratory incubation experiments (90 days) were conducted at a constant temperature (25 °C) to quantify the bioavailable dissolved organic matter (DOM) and the possible degradation rate coefficients. The results showed that 41 ± 12% of dissolved organic carbon (DOC) and 47 ± 17% of dissolved organic nitrogen (DON) were B and B respectively, with their stoichiometry found to be higher than the Redfield ratio. A first order exponential non-linear fitting routine was used to estimate pool sizes. The degradation rate constant (k) for the B varied from 0.127-0.329 d and B from 0.043-0.306 d during the study period. Half-lives of the B and B ranged from 2.1-5.4 and 2.2-15.9 days, respectively. Overall, the results showed that a fraction of the labile DON was transported from the lagoon to the adjacent coastal sea.

International Journal of Environmental Science and Technology, 2017

Journal of Hydrology, 2017

Science of The Total Environment, 2021

Chemistry and Ecology, 2017

ABSTRACT The spatial distribution of the C/N ratios and variations in δ13C and δ15N of suspended ... more ABSTRACT 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 situ 15N 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−1 during pre-monsoon and post-monsoon seasons. New production and regenerated production in the shallow lagoon was also estimated by calculating f-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 the f-ratio from post- to pre-monsoon indicated a dominance of mineralisation over the new production.

International Journal of Environmental Science and Technology, 2021

Bulletin of environmental contamination and toxicology, Jan 14, 2017

The spatio-temporal distribution and the controlling factors of petroleum hydrocarbons (PHCs) in ... more The spatio-temporal distribution and the controlling factors of petroleum hydrocarbons (PHCs) in sediments of Chilika lagoon was investigated. Samples were collected during three seasons and quantified using UV-fluorescence spectroscopy. Concentrations of PHCs in surface sediments varies from 0.18 to 12.13 ppm (mean 3.71 ± 3.94 ppm). Compared to the lagoon, the monitoring stations adjacent to jetties with high boating activities tend to have higher PHC concentrations, suggesting that the contribution is likely to be from fossil fuel combustion and accidental seepage. The sediment organic matter (OM) of Chilika ranges from 0.26% to 6.23%. PHC maintains a positive correlation with OM (p < 0.05; f = 0.334), indicating the long term deposition of PHC as sediment OM. However, there is no significant relation between PHC and sediment texture, indicating its negligible control over PHC. The recorded PHC concentrations are below the threshold limit (70 ppm) as classified by United States...