Unraveling prokaryotic diversity distribution and functional pattern on nitrogen and methane cycling in the subtropical Western North Pacific Ocean.

Prokaryotes play an important role in marine nitrogen and methane cycles. However, their community changes and metabolic modifications to the concurrent impact of ocean warming (OW), acidification (OA), deoxygenation (OD), and anthropogenic‑nitrogen-deposition (AND) from the surface to the deep ocean remains unknown. We examined here the amplicon sequencing approach across the surface (0-200 m; SL), intermediate (200-1000 m; IL), and deep layers (1000-2200 m; DL), and characterized the simultaneous impacts of OW, OA, OD, and AND on the Western North Pacific Ocean prokaryotic changes and their functional pattern in nitrogen and methane cycles.

Ocean warming and acidification affect the transitional C:N:P ratio and macromolecular accumulation in the harmful raphidophyte Heterosigma akashiwo.

Despite an increase in ocean warming and acidification that is expected to increase the number of harmful algal species worldwide, the population of the raphidophyte Heterosigma akashiwo has been reported to be reduced. However, how this species physically and metabolically modifies transitional C:N:P ratio and macromolecule accumulation is unknown. Considering 1st, 10th, and 20th culture generations under present (low-temperature; low-carbon-dioxide [LTLC] 21 °C; pCO 400 ppm) and future (high-temperature; high-carbon-dioxide [HTHC] 25 °C; pCO 1000 ppm) ocean conditions, we examined transitional C:N:P ratio and macromolecule level changes and performed transcriptome sequencing.

Transitional traits determine the acclimation characteristics of the coccolithophore Chrysotila dentata to ocean warming and acidification.

Ocean warming and acidification interactively affect the coccolithophore physiology and drives major biogeochemical changes. While numerous studies investigated coccolithophore under short-term conditions, knowledge on how different transitional periods over long-exposure could influence the element, macromolecular and metabolic changes for its acclimation are largely unknown. We cultured the coccolithophore Chrysotila dentata, (culture generations of 1st, 10th, and 20th) under present (low-temperature low-carbon-dioxide [LTLC]) and projected (high-temperature high-carbon-dioxide [HTHC]) ocean conditions.

Acclimation traits determine the macromolecular basis of harmful dinoflagellate Alexandrium minutum in response to changing climate conditions.

Ocean warming and acidification are expected to have profound impacts on the marine ecosystem, although the dinoflagellate Alexandrium minutum is reported to be acclimated to such conditions. However, it is unknown on the transition time scale how this species physiologically adjusts their element accumulation and associated resource allocation for this process. We designed a set of experiments to examine how different culture generations (1, 5, and 10) change their cell physiology, cellular quotas and macromolecular cellular contents related to functional processes in A.

Water quality shifts the dominant phytoplankton group from diatoms to dinoflagellates in the coastal ecosystem of the Bohai Bay.

In this study, we conducted two cruises in the Bohai Bay (China) focusing on phytoplankton community and relation to water quality. The evaluation revealed that most of the open area was non-eutrophic, whereas the river inlet had severe eutrophication. Phytoplankton populations respond differently to different aquatic environments and are controlled by more than two factors, as revealed by aggregated boosted tree analysis.

Variation in biogenic calcite production by coccolithophores across mesoscale eddies in the Bay of Bengal.

Coccolithophore calcite production (CP) was investigated for the first time in the Bay of Bengal. Against expectation, calcite production was not fueled by the nutrient-enriched cold eddy because of the reduced light penetration. CP rate was observed to be higher at the anticyclonic eddy possibly benefited from rare species production.

Quantitative Proteomic Profiling of Marine Diatom in Response to Temperature and Silicate Induced Environmental Stress.

Global warming is expected to reduce the nutrient concentration in the upper ocean and affect the physiology of marine diatoms, but the underlying molecular mechanisms controlling these physiological changes are currently unknown. To understand these mechanisms, here we investigated iTRAQ based proteomic profiling of diatom in a multifactorial experimental with a combining change of temperature and silicate concentrations. In total, 3369 differently abundant proteins were detected in four different environmental conditions, and the function of all proteins was identified using Gene Ontology and KEGG pathway analysis.

Comparative Proteomic Analysis Reveals New Insights Into the Common and Specific Metabolic Regulation of the Diatom to the Silicate and Temperature Availability.

Silicate (Si) and temperature are essential drivers for diatom growth and development in the ocean. Response of diatoms to these particular stress has been investigated; however, their common and specific responses to regulate intracellular development and growth are not known. Here, we investigated the combination of physiological characteristics and comparative proteomics of the diatom grown in silicate- and temperature-limited conditions.

Transcriptomic reprogramming of the oceanic diatom Skeletonema dohrnii under warming ocean and acidification.

Under ocean warming and acidification, diatoms use a unique acclimation and adaptation strategy by saving energy and utilizing it for other cellular processes. However, the molecular mechanisms that underlie this reprogramming of energy utilization are currently unknown. Here, we investigate the metabolic reprogramming of the ecologically important diatom Skeletonema dohrnii grown under two different temperature (21°C and 25°C) and pCO (400 and 1000 ppm) levels, utilizing global transcriptomic analysis.

The Biotechnological Potential of the Marine Diatom to the Elevated Temperature and CO Concentration.

Marine diatoms are promising candidates for biotechnological applications, since they contain high-value compounds, naturally. To facilitate the production of these compounds, stress conditions are often preferable; however, challenges remain with respect to maximizing a metabolic potential for the large-scale cultivation. Here, we sequenced the transcriptome of diatom under the actual (21 °C, 400 ppm) and elevated (25 °C, 1000 ppm) temperature and CO condition.

Assessment of trace metal contamination in the marine sediment, seawater, and bivalves of Parangipettai, southeast coast of India.

Industrial and domestic discharge into the coastal environment has driven us to propose an integrated approach to delineate stations contaminated with metals on the Parangipettai coast by collecting sediment and seawater samples monthly at 18 stations from 2015 to 2017. Descriptive statistics revealed that the concentrations of some metals in the sediment and seawater samples were beyond the permissible level. Further, factor analysis showed a sampling adequacy of 0.

Quantitative Proteomic Analysis Reveals Novel Insights into Intracellular Silicate Stress-Responsive Mechanisms in the Diatom .

Diatoms are a successful group of marine phytoplankton that often thrives under adverse environmental stress conditions. Members of the genus are ecologically important which may subsist during silicate stress and form a dense bloom following higher silicate concentration. However, our understanding of diatoms' underlying molecular mechanism involved in these intracellular silicate stress-responses are limited.

Distribution of living coccolithophores in eastern Indian Ocean during spring intermonsoon.

We studied the biodiversity of autotrophic calcareous coccolithophore assemblages at 30 locations in the Eastern Equatorial Indian Ocean (EEIO) (80°-94°E, 6°N-5°S) and evaluated the importance of regional hydrology. We documented 26 species based on the identification of coccospheres and coccoliths, respectively. The coccolithophore community was dominated by Gephyrocapsa oceanica, Emiliania huxleyi, Florisphaera profunda, Umbilicosphaera sibogae, and Helicosphaera carteri.

Evaluation of the environmental quality of Parangipettai, Southeast Coast of India, by using multivariate and geospatial tool.

The anthropogenic pressure in recent years has driven us to investigate the environmental quality at 22 stations in Parangipettai by collecting seawater samples monthly from 2014 to 2015. The sampling stations were grouped into three different environments, namely, Vellar Estuary (VE), Coleroon Estuary (CE), and Open Sea (OS). Factor analysis showed a total variance of 65.

Nitrogen Fixation by Trichodesmium and unicellular diazotrophs in the northern South China Sea and the Kuroshio in summer.

Distribution of diazotrophs and their nitrogen fixation activity were investigated in the northern South China Sea (nSCS) and the Kuroshio from July 16th to September 1st, 2009. N fixation activities in whole seawater and <10 μm fraction at the surface were measured by acetylene reduction assay. Higher activities were observed at the East China Sea (ECS) Kuroshio and the nSCS shelf.