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Publications (50)
Phytoplankton, the primary producers of all aquatic systems, form the base of the marine food web. Any change in the environmental settings of the given ecosystem will affect the phytoplankton community structure of the region. In the present work, water sampling was carried out from the poorly explored polar region, beneath the sea ice during the...
In the Southern Ocean (SO) marine ecosystem, the interplay between CO2 sink and climate change is closely linked to the shifting plankton communities, leading to potentially wide-ranging biogeochemical effects. Within the Indian sector of the Southern Ocean (ISSO), the phytoplankton community was predominantly composed of Fragilariopsis spp., follo...
Phytoplankton are important indicators of climate change as they form the base of the marine food web, thus playing a major role in the biogeochemical cycling of the ocean. The abundance, distribution, and community structure of phytoplankton varies from place to place, and within the same water body. We carried out ~1 month (1st to 23rd January, 2...
There is very little knowledge on microplastic pollution in the Western Ghats (WG), a heritage site in southwest India. To address this, we have studied the spatiotemporal variations of sedimentary microplastics (MPs) from the River Sharavathi, a pristine river in the Western Ghats (WG), southern India. The rich biodiversity in the region makes it...
The bio-optical characteristics of the surface ocean play a pivotal role in radiative transfer
and photosynthetic carbon fixation. To examine spatiotemporal variability of bio-optical
properties in the tropical Indian Ocean, a 10-day time-series comparative study was made at one fixed and 3 variable stations in the southwestern tropical Indian Ocea...
To understand the role of physical processes and their interannual variability on the dissolved nutrient concentration and phytoplankton biomass distribution, field data collected in the Indian sector of the Southern Ocean (ISSO) during the austral summer of 2009–2011 are used. In the subtropical zone, macronutrients were limited (N:P < 1, N:Si < 1...
There is very little knowledge on microplastic pollution in the Western Ghats (WG), a heritage site in southwest India. To address this, we have studied the seasonal variations of sedimentary microplastics (MPs) from River Sharavathi - a pristine river in the WG, southern India. We analysed the sedimentological and carbon content (organic and inorg...
Seychelles-Chagos thermocline ridge is one of the major upwelling area in the tropical Indian Ocean, where planktons are known to have large impacts on ocean ecosystem and biogeochemical cycles. Time series assessments of surface zooplankton abundance, biovolume, and community composition were carried out in the Indian Ocean during June 2014. In th...
20 Mesoscale eddies influence the nutrient distribution and modulate the phytoplankton growth. 21 The present study addressed the influence of cyclonic and anticyclonic eddies on the 22 variability of particulate organic matter composition at the Subtropical Front of the Indian 23 Ocean sector of the Southern Ocean during austral summer 2012 and 20...
The existing oligotrophic conditions in the southwest tropical Indian Ocean (SWTIO) is believed to be one of the causes for low phytoplankton productivity (PP) observed in this area. Though many remote sensing based studies on PP have been carried out in SWTIO, studies on in situ estimation of PP and its cause(s) of variability are scarce. Thus, to...
The five major rivers (Ganges, Mahanadi, Godavari, Krishna, and Cauvery) flowing in the north eastern Indian Ocean greatly influence the biogeochemical cycling nearshore waters of the east coast of India. For example, estuaries which are located at the interface between land and ocean are an area of intense recycling of organic matter with a large...
Ballast water transport is considered as one of the major vectors for dispersal of microplastics around the global oceans. In this commentary, a simple, inexpensive solution has been proposed to reduce microplastic pollution and its mobility via ballast water. A screening chamber (with stainless steel three layered mesh) is proposed to be attached...
Phytoplankton, the primary producers in all aquatic systems, plays an important role in key biogeochemical processes that are linked to higher trophic levels and climate variability. The present study deals with the phytoplankton community structure in the Indian Ocean, particularly in the higher latitudes with respect to environmental variables to...
The Southern Ocean is a very dynamic ecosystem comprising many fronts and zones. Among the fronts, the Subtropical Front (STF) is a region of high eddy activity exhibiting spatio-temporal variability. The variability of food web structure in such a dynamic system characterised by frequent eddy events and their influence on the plankton community st...
During Austral summer 2012, seawater samples were collected from the upper 120 m of the water column, across the frontal zones in the Indian Ocean sector of the Southern Ocean. Suspended particulate organic matter from seawater was characterised, from its organic carbon and nitrogen content, and δ¹³C(POM). There was a marked difference in δ¹³C(POM)...
The existing oligotrophic conditions in the southwest tropical Indian Ocean (SWTIO) is believed to be one of the causes for low phytoplankton productivity (PP) observed in this area. Though many remote sensing based studies on PP have been carried out in SWTIO, studies on in situ estimation of PP and its cause(s) of variability are scarce. Thus, to...
Ongoing sea-ice melting and associated environmental changes influence the bloom phenology and biogeochemistry of the Arctic Ocean. Kongsfjorden, a fjord in Svalbard, has already undergone the transition of being sea-ice covered in winter to sea-ice free, and now stands vulnerable to Atlantic water intrusion and glacier melting. We monitored physic...
The northern boundary of the Indian sector of Southern Ocean is marked by the juncture of the Agulhas Return Front and the southern Subtropical Front and is a hydrographically dynamic region. During austral summer, a time series study (13th to 15th January 2012) was conducted in this region (40°S, 58°30′E) to discuss the episodic biochemical change...
Phytoplankton biomass (chlorophyll-a) and community structure in the water column was analyzed across various frontal regions in the Subtropical Front (STF), Sub-Antarctic Front (SAF), Polar Front-1 (PF1) and Polar Front-2 (PF2) in the Indian Ocean sector of the Southern Ocean (SO) during the austral summer (January–February) of 2013 and 2015. The...
The monsoon-influenced tropical Indian region is quite different from the subtropical, temperate, and polar regions in terms of hydrographic conditions due to monsoonal activities. These regions can unravel some important roles of cyanobacteria in the aquatic ecosystem. The oligotrophic waters of the Indian Ocean mainly comprise Prochlorococcus and...
This study investigates the effect of metals (cadmium, lead, mercury, and tellurium) and organic pollutants (benzene, diesel, lindane, and xylene) on a dinoflagellate—Prorocentrum sigmoides Böhm—and its associated culturable bacteria. Two bacterial cultures (Bacillus subtilis strain PD005 and B. xiamensis strain PD006) were isolated from P. sigmoid...
Microplastic pollution in marine waters around the globe is increasing exponentially. This is the first comprehensive review which focuses on microplastics as a source and vector for metals, antibiotics, toxic chemicals, pathogenic bacteria (Vibrio cholerae), and Harmful Algal Bloom (HAB)-forming dinoflagellates across the continents through ballas...
Phytoplankton are microscopic, unicellular organisms that play a pivotal role as the base of food webs in aquatic systems. Depending on the econiche inhabited, the sampling strategies and procedures employed for analysis differ. In this chapter, we discuss the sampling strategies used for water and sediment, in diverse coastal and oceanic environme...
The abundance and vertical distribution of zooplankton community structure in the mesopelagic zone are important to better understand their role in the food web dynamics in the Southern Ocean ecosystem. During the austral summer of 2015, in the Indian sector of the Southern Ocean, the vertical profiles of zooplankton community structures between 0...
Observations of iodine oxide (IO) were made in the Indian Ocean and the Southern Ocean marine boundary layer (MBL) during the 8th Indian Southern Ocean Expedition. IO was observed almost ubiquitously in the open ocean with larger mixing ratios south of the Polar Front (PF). Contrary to previous reports, IO was not positively correlated to sea surfa...
Upper layer diapycnal mixing in the Subtropical Front (STF) was estimated using microstructure shear profiles collected from the Indian sector of the Southern Ocean (ISSO) during the austral summer of 2012. Observations were made in the northern and southern boundary of the highly mesoscale turbulent STF, which is characterized by the presence of t...
Prorocentrum rhathymum,a toxic dinoflagellate, was isolated for the first time from coastal waters of the eastern Arabian Sea. Batch cultures were grown and cell pellets were extracted in methanol for analysis of algal toxin. LCMS/MS studies exhibited presence of dinophysis toxin 1 (DTX1) with no detectable Okadaic Acid. Growth rates varied between...
Phytoplankton composition plays a major role in biogeochemical cycles of the ocean. The intensity of carbon fixation and export is strongly dependent on the phytoplankton community. Yet, the contribution of different types of phytoplankton to the total production on various communities is still poorly understood in the Indian Ocean sector of Southe...
This study reports nitrogen uptake rate (using 15N tracer) of phytoplankton in surface waters of different frontal zones in the Indian sector of the Southern Ocean (SO) during austral summer of 2013. The investigated area encompasses four major frontal systems, i.e., the subtropical front (STF), subantarctic front (SAF), polar front-1 (PF1) and pol...
Pollution in marine environments has been widely studied because of its impact, both direct and indirect, on human livelihood. Pollution may arise from different sources, the most well known being influx of domestic sewage, industrial waste and mining effluents. Shipping activities also contribute to pollution, either through accidental oil spills,...
This study investigates the effects of light and temperature on the surface water diatoms and chlorophytes, phytoplankton in the Indian Ocean sector of the Southern Ocean (SO) during the austral summer of 1998‒2014. Significant longitudinal variations in hydrographic and biological parameters were observed at the Sub tropical front (STF), Sub Antar...
In a shipboard microcosm experiment we manipulated cobalt (Co), copper (Cu), iron (Fe), and Fe+Co availability in surface water samples collected during austral summer of 2013 from a Polar front (PF) location in the Indian Sector of Southern Ocean, to examine the responses of phytoplankton as well as bacterial community (BC) to these micronutrient...
The probable cause for photoinhibition of primary productivity (PP) in the surface layers of the Indian Ocean sector of the Southern Ocean (SO) was studied during the austral summer (February) 2010. Chlorophyll a (Chl a) and PP values were higher for polar stations compared to offshore stations and showed surface maxima; however, subsurface Chl a m...
Algal blooms have been documented along the west and east coasts of India. A review of bloom occurrences in Indian waters from 1908 to 2009 points out that a total of 101 cases have been reported. A comparison of the bloom cases reported before and after the 1950s reveals that there is an increase in the number of bloom occurrences. The reports of...
Harmful algal blooms (HABs) have been documented along the coasts of India and the ill effects felt by society at large. Most of these reports are from the Arabian Sea, west coast of India, whereas its counterpart, the Bay of Bengal (BOB), has remained unexplored in this context. The unique characteristic features of the BOB, such as large amount o...
Spatial and temporal variations in surface water phytoplankton pigment distribution in the Bay of Bengal
were studied during the spring intermonsoon (SpIM, February–April) and the commencement of the summer
monsoon (CSM, May–June), using pigment and diagnostic indices. The Prokaryotic pigment index (ProkDP)
was dominant at all the oceanic stations...
Dinoflagellates form an important component of marine and freshwater phytoplankton. They are a remarkably diverse and complex group with various modes of nutrition and ability to produce toxins, and are major contributors to harmful algal blooms. In the present work, we identify the presence of Karlodinium veneficum in India. Its detection in the c...
The planktonic diatom genus Skeletonema is common in Indian coastal waters. Recent taxonomic studies have uncovered high diversity in this genus, and it is expected that several species occur also in the highly diverse marine habitats along the Indian coastline. In the present study, material of a culture raised from a specimen isolated from a wate...
A non-linear model that uses satellite-derived chlorophyll to estimate water-column primary production was developed and tested using data from the Delagoa Bight, where the model results compared well with local estimates. The data were also used to assess variations in phytoplankton biomass and daily water-column primary production (PZT; mg C m−2...
Diatoms are one of the early colonisers on surfaces submerged in the photic zone of the environment. Their colonisation on man made structures, termed biofouling, has enormous implications in the marine industry. The processes involved in biofouling and the role of Diatoms is presented. The article also provides an overview of the current and poten...
The measurement of primary production is of great importance because of its significance to the problems of aquatic ecology and fishery management. The interaction of light intensity, temperature and nutrient levels determines the photosynthetic efficiency of an aquatic ecosystem. Studies on primary productivity was carried out in Karwar bay at thr...
