scholarly journals Eco-Biology of Photosynthetic Picoeukaryotes in a Monsoon Influenced Tropical Bay: A Flow Cytometric and Chemotaxonomic Approach

2021 ◽  
Author(s):  
Smita Mitbavkar ◽  
Samantha D'souza
Keyword(s):  
Food Web ◽  
Environmental Conditions ◽  
High Performance ◽  
Microbial Food Web ◽  
Nutrient Concentrations ◽  
Flow Cytometric ◽  
South West Monsoon ◽  
Total Phytoplankton ◽  
West Monsoon ◽  
Tropical Bay

Abstract The composition and ecology of photosynthetic picoeukaryotes (PPEUK) are essential for microbial food web functioning. We hypothesize that the simultaneous use of flow cytometry (FCM) and High-Performance-Liquid-Chromatography (HPLC) tools will aid in discerning the dominant PPEUK groups contributing to abundance and biomass under prevailing environmental conditions. The PPEUK seasonal community abundance and pigment biomass were investigated from a south-west monsoon influenced tropical bay from June 2015-May 2016. A size-fractionated (< 3 µm) approach using FCM and HPLC revealed five and six PPEUK groups, respectively. Picocryptophytes dominated the PPEUK biomass under varied environmental conditions, whereas Picodiatoms contributed substantially, being abundant under turbulent, low-temperature, nutrient (NO3−, SiO44−) enriched conditions. The Picochlorophytes dominated the community numerically. The relatively higher abundance and biomass of Picoprasinophytes and a positive correlation with NO3− and NH4+ imply proliferation under higher nutrient concentrations. The least contributors to biomass were Picodinoflagellates and Picoprymnesiophytes. The relatively larger cell size of Picocryptophytes and Picodiatoms resulted in higher cumulative biomass, signifying their role in the microbial food web. Our study proposes incorporation of additional indicator pigments in algorithms used to estimate coastal picophytoplankton contribution to total phytoplankton biomass to avoid discrepancies.

scholarly journals Changing Ecological Conditions in the Marine Environment Generate Different Microbial Food Web Structures in a Repeatable Manner

2022 ◽  
Vol 8 ◽  
Author(s):  
Mladen Šolić ◽  
Danijela Šantić ◽  
Stefanija Šestanović ◽  
Grozdan Kušpilić ◽  
Frano Matić ◽  
...  
Keyword(s):  
Food Web ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Prey Selection ◽  
Gas Analysis ◽  
Microbial Food Web ◽  
Large Spatial Scale ◽  
Spatial And Temporal Scales ◽  
Distinct Structure ◽  
Functional Features

The mechanisms responsible for the development of various structural and functional features of the microbial food web (MFW) and their dynamics at spatial and temporal scales, which are important for predicting their responses to future environmental changes, are largely unknown. More than 3000 datasets of environmental and microbial variables collected over a decade on a seasonal and large spatial scale in the Adriatic Sea were analyzed. The sets of environmental variables were classified into four clusters (representing different environmental states) using Neural Gas analysis and the differences in MFW structure between the clusters were analyzed. Different variants of MFW evolve in the different clusters in terms of the abundance of MFW components, their ratios, growth and grazing rates, predator preference in prey selection, the strength of predator-prey interaction, and the relative importance of top-down and bottom-up control. However, these clusters are neither spatially nor temporally fixed; rather, the area studied represents a mosaic of different environmental conditions that alternate from one state to another on a time scale. In each of the environmental states, a distinct structure of MFW develops that shows consistent and repeatable changes that strictly follow the switching in environmental conditions from one state to another.

scholarly journals Relative Contributions ofHalobacteriovoraxand Bacteriophage to Bacterial Cell Death under Various Environmental Conditions

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Huan Chen ◽  
Edward A. Laws ◽  
Julio L. Martin ◽  
Timkhite-Kulu Berhane ◽  
Paul A. Gulig ◽  
...  
Keyword(s):  
Food Web ◽  
Environmental Conditions ◽  
Vibrio Vulnificus ◽  
Microbial Food Web ◽  
Nutrient Media ◽  
Bacterial Mortality ◽  
Content Type ◽  
Practical Applications ◽  
Cycling Of Nutrients

ABSTRACTThe role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence thatBdellovibrioand like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator’s contribution. Here we investigated the contribution ofHalobacteriovorax, one of the BALOs, and bacteriophages when incubated with their common prey,Vibrio vulnificus, in a seawater microcosm. We observed thatHalobacteriovoraxwas the greatest responder to the prey, increasing 18-fold with a simultaneous 4.4-log-unit reduction ofV. vulnificusat 40 h, whereas the bacteriophage population showed no significant increase. In subsequent experiments to formulate a medium that would support the predatory activities and replication of both predators, low-nutrient media favored the predation and replication of theHalobacteriovorax, whereas higher-nutrient media enhanced phage growth. The greatest prey reduction and replication of bothHalobacteriovoraxand phage were observed in media with moderate nutrient levels. Additional experiments show that the predatory activities of both predators were influenced by environmental conditions, specifically, temperature and salinity. The two predators combined exerted greater control onV. vulnificus, a synergism that may be exploited for practical applications to reduce bacterial populations. These findings suggest that along with bacteriophage and protists,Halobacteriovoraxhas the potential to have a prominent role in bacterial mortality and cycling of nutrients, two vital ecologic functions.IMPORTANCEAlthough much has been reported about the marine microbial food web and the role of micropredators, specifically viruses and protists, the contribution ofBdellovibrio-like predators has largely been ignored, posing a major gap in understanding food web processes. A complete scenario of the microbial food web cannot be developed until the roles of all major micropredators and the magnitude of their contributions to bacterial mortality, structuring of microbial communities, and cycling of nutrients are assessed. Here we show compelling evidence thatHalobacteriovorax, a predatory bacterium, is a significant contributor to bacterial death and, in some cases, may rival viruses as agents of bacterial mortality. These results advance current understanding of the microbial loop and top-down control on the bacterial community.

Forecasting of Summer Monsoon Rainfall over Gangetic West Bengal, India Utilising Intrinsic Mode Functions, Linear and Neural Regression

2020 ◽  
Vol 12 (1) ◽  
pp. 60-69 ◽  
Author(s):  
Pijush Basak
Keyword(s):  
Neural Network ◽  
West Bengal ◽  
Monsoon Rainfall ◽  
Linear Part ◽  
Intrinsic Mode Functions ◽  
Quasi Biennial Oscillation ◽  
Nonlinear Part ◽  
South West ◽  
South West Monsoon ◽  
West Monsoon

The South West Monsoon rainfall data of the meteorological subdivision number 6 of India enclosing Gangetic West Bengal is shown to be decomposable into eight empirical time series, namely Intrinsic Mode Functions. This leads one to identify the first empirical mode as a nonlinear part and the remaining modes as the linear part of the data. The nonlinear part is modeled with the technique Neural Network based Generalized Regression Neural Network model technique whereas the linear part is sensibly modeled through simple regression method. The different Intrinsic modes as verified are well connected with relevant atmospheric features, namely, El Nino, Quasi-biennial Oscillation, Sunspot cycle and others. It is observed that the proposed model explains around 75% of inter annual variability (IAV) of the rainfall series of Gangetic West Bengal. The model is efficient in statistical forecasting of South West Monsoon rainfall in the region as verified from independent part of the real data. The statistical forecasts of SWM rainfall for GWB for the years 2012 and 2013 are108.71 cm and 126.21 cm respectively, where as corresponding to the actual rainfall of 93.19 cm 115.20 cm respectively which are within one standard deviation of mean rainfall.

scholarly journals Enhanced Viral Activity in the Surface Microlayer of the Arctic and Antarctic Oceans

2021 ◽  
Vol 9 (2) ◽  
pp. 317
Author(s):  
Dolors Vaqué ◽  
Julia A. Boras ◽  
Jesús Maria Arrieta ◽  
Susana Agustí ◽  
Carlos M. Duarte ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Food Web ◽  
Physicochemical Characteristics ◽  
The Arctic ◽  
Microbial Food Web ◽  
Surface Microlayer ◽  
Polar Regions ◽  
Nutrient Inputs ◽  
Viral Activity ◽  
The Impact

The ocean surface microlayer (SML), with physicochemical characteristics different from those of subsurface waters (SSW), results in dense and active viral and microbial communities that may favor virus–host interactions. Conversely, wind speed and/or UV radiation could adversely affect virus infection. Furthermore, in polar regions, organic and inorganic nutrient inputs from melting ice may increase microbial activity in the SML. Since the role of viruses in the microbial food web of the SML is poorly understood in polar oceans, we aimed to study the impact of viruses on prokaryotic communities in the SML and in the SSW in Arctic and Antarctic waters. We hypothesized that a higher viral activity in the SML than in the SSW in both polar systems would be observed. We measured viral and prokaryote abundances, virus-mediated mortality on prokaryotes, heterotrophic and phototrophic nanoflagellate abundance, and environmental factors. In both polar zones, we found small differences in environmental factors between the SML and the SSW. In contrast, despite the adverse effect of wind, viral and prokaryote abundances and virus-mediated mortality on prokaryotes were higher in the SML than in the SSW. As a consequence, the higher carbon flux released by lysed cells in the SML than in the SSW would increase the pool of dissolved organic carbon (DOC) and be rapidly used by other prokaryotes to grow (the viral shunt). Thus, our results suggest that viral activity greatly contributes to the functioning of the microbial food web in the SML, which could influence the biogeochemical cycles of the water column.

scholarly journals Insight into the Metabolic Profiles of Pb(II) Removing Microorganisms

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4008
Author(s):  
Carla Cilliers ◽  
Evans M. N. Chirwa ◽  
Hendrik G. Brink
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Microbial Consortium ◽  
Luria Bertani ◽  
Nutrient Concentrations ◽  
Batch Experiments ◽  
Metabolic Study ◽  
Luria Bertani Broth ◽  
Tandem Mass Spectroscopy ◽  
Insight Into

The objective of the study was to gather insight into the metabolism of lead-removing microorganisms, coupled with Pb(II) removal, biomass viability and nitrate concentrations for Pb(II) bioremoval using an industrially obtained microbial consortium. The consortium used for study has proven to be highly effective at removing aqueous Pb(II) from solution. Anaerobic batch experiments were conducted with Luria-Bertani broth as rich growth medium over a period of 33 h, comparing a lower concentration of Pb(II) with a higher concentration at two different nutrient concentrations. Metabolite profiling and quantification were conducted with the aid of both liquid chromatography coupled with tandem mass spectroscopy (UPLC-HDMS) in a “non-targeted” fashion and high-performance liquid chromatography (HPLC) in a “targeted” fashion. Four main compounds were identified, and a metabolic study was conducted on each to establish their possible significance for Pb(II) bioremoval. The study investigates the first metabolic profile to date for Pb(II) bioremoval, which in turn can result in a clarified understanding for development on an industrial and microbial level.

Modeling the microbial food web

1994 ◽  
Vol 28 (2) ◽  
pp. 303-319 ◽  
Author(s):  
H. W. Ducklow
Keyword(s):  
Food Web ◽  
Microbial Food Web

Abundance and Community Structure of Picoplankton and Protists in the Microbial Food Web of Barguzin Bay, Lake Baikal

2005 ◽  
Vol 39 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Hiroyuki Ueno ◽  
Toshiya Katano ◽  
Shin-Ichi Nakano ◽  
Osamu Mitamura ◽  
Kaori Anbutsu ◽  
...  
Keyword(s):  
Community Structure ◽  
Food Web ◽  
Lake Baikal ◽  
Microbial Food Web

Recurrent landslides in Southern Western Ghats, India: A changing environmental perspective

2021 ◽  
Author(s):  
Asokan Laila Achu ◽  
Girish Gopinath
Keyword(s):  
Western Ghats ◽  
Hot Spot ◽  
Extreme Rainfall ◽  
Vital Role ◽  
Monsoon Period ◽  
Extreme Rainfall Events ◽  
South West ◽  
South West Monsoon ◽  
West Monsoon ◽  
The Western Ghats

&lt;p&gt;The Western Ghats (WG), an elevated passive continental margin along the southwestern coast of India, is the most widely populated biodiversity hot spot in the world. Monsoon climate is prevalent throughout the length of the Western Ghats. The WG region is prone to the occurrence of various hydro-climatic disasters such as extreme rainfall-driven floods and landslides. During the past 100 years, landslides and floods caused by extreme rainfall events in the WG have occurred in 1924 and 1979; but the most disastrous event, in terms of area of impact, loss of life and economic impact, occurred in August 2018. Generally, the south-west monsoon (Indian summer monsoon) occurs in the first week of June and extends up to September and the Indian Meteorological Department (IMD) predicted above-normal rainfall of 13% during the month of August 2018. But the State received an excess of 96% during the period from 1st to 30th August 2018, and 33% during the entire monsoon period till the end of August. The unprecedented heavy rains, storms, floods and associated thousands of landslides have caused exorbitant losses including 400 life losses, over 2.20 lakh people were displaced, and 20000 homes and 80 dams were damaged or destructed. This study aimed to elucidate the reasons behind the thousands of landslides caused in WG using observed and field evidences. Changes in south-west monsoon pattern and rainfall intensity played a vital role in the occurrence of landslides in WG. Further, the extensive causalities are the result of anthropogenic disturbances including landscape alterations and improper landuse practices in the hilly tracks of WG. The major causative factors for series of landslides in various segments of WG is due to hindrance of lower order streams/springs, vertical cutting, intensive quarrying, unscientific rain pits &amp; man-made structures together with erratic rainfall triggered major and minor landslides in various segments of WG. The present investigation concludes that a scientific landuse policy and geoscientific awareness is essential to mitigate the environment.&lt;/p&gt;

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