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1.
Upwelling Bays: How Coastal Upwelling Controls Circulation, Habitat, and Productivity in Bays.
Largier, JL
Annual review of marine science. 2020;:415-447
Abstract
Bays in coastal upwelling regions are physically driven and biochemically fueled by their interaction with open coastal waters. Wind-driven flow over the shelf imposes a circulation in the bay, which is also influenced by local wind stress and thermal bay-ocean density differences. Three types of bays are recognized based on the degree of exposure to coastal currents and winds (wide-open bays, square bays, and elongated bays), and the characteristic circulation and stratification patterns of each type are described. Retention of upwelled waters in bays allows for dense phytoplankton blooms that support productive bay ecosystems. Retention is also important for the accumulation of larvae, which accounts for high recruitment in bays. In addition, bays are coupled to the shelf ecosystem through export of plankton-rich waters during relaxation events. Ocean acidification and deoxygenation are a concern in bays because local extrema can develop beneath strong stratification.
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2.
Progress in the Study and Use of Seawater Vegetables.
Li, L, Zhao, Y, Han, G, Guo, J, Meng, Z, Chen, M
Journal of agricultural and food chemistry. 2020;(22):5998-6006
Abstract
As global soil salinization increases, halophytes that can grow in saline soils are the primary choice for improving soil quality. Some halophytes can even be irrigated with seawater and used as vegetables. These so-called seawater vegetables include those that can be planted on saline and alkali soils and some edible halophytes and ordinary vegetables that are salt-tolerant. The cultivation of seawater vegetables on saline soil has become a matter of increasing interest. In this review, we focus on the salt-tolerance mechanisms and potential applications of some seawater vegetables. We also summarize their value to health, medicine, industry, and the economy as a whole. Further improvement and development to support the use of seawater vegetables will require in-depth research at the cellular and molecular levels.
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3.
GEOTRACES: Accelerating Research on the Marine Biogeochemical Cycles of Trace Elements and Their Isotopes.
Anderson, RF
Annual review of marine science. 2020;:49-85
Abstract
The biogeochemical cycles of trace elements and their isotopes (TEIs) constitute an active area of oceanographic research due to their role as essential nutrients for marine organisms and their use as tracers of oceanographic processes. Selected TEIs also provide diagnostic information about the physical, geological, and chemical processes that supply or remove solutes in the ocean. Many of these same TEIs provide information about ocean conditions in the past, as their imprint on marine sediments can be interpreted to reflect changes in ocean circulation, biological productivity, the ocean carbon cycle, and more. Other TEIs have been introduced as the result of human activities and are considered contaminants. The development and implementation of contamination-free methods for collecting and analyzing samples for TEIs revolutionized marine chemistry, revealing trace element distributions with oceanographically consistent features and new insights about the processes regulating them. Despite these advances, the volume and geographic coverage of high-quality TEI data by the end of the twentieth century were insufficient to constrain their global biogeochemical cycles. To accelerate progress in this field of research, marine geochemists developed a coordinated international effort to systematically study the marine biogeochemical cycles of TEIs-the GEOTRACES program. Following a decade of planning and implementation, GEOTRACES launched its main field effort in 2010. This review, roughly midway through the field program, summarizes the steps involved in designing the program, its management structure, and selected findings.
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4.
Aequoribacter fuscus gen. nov., sp. nov., a new member of the family Halieaceae, isolated from coastal seawater.
Li, SH, Song, J, Kang, I, Hwang, J, Cho, JC
Journal of microbiology (Seoul, Korea). 2020;(6):463-471
Abstract
A Gram-stain-negative, rod-shaped, obligately aerobic, nonflagellated, and chemoheterotrophic bacterium, designated IMCC3088T, was isolated from coastal seawater of the Yellow Sea. The 16S rRNA gene sequence analysis indicated that this strain belonged to the family Halieaceae which shared the highest sequence similarities with Luminiphilus syltensis NOR5-1BT (94.5%) and Halioglobus pacificus S1-72T (94.5%), followed by 92.3-94.3% sequence similarities with other species within the aforementioned family. Phylogenetic analyses demonstrated that strain IMCC3088T was robustly clustered with Luminiphilus syltensis NOR5-1BT within the family Halieaceae. However, average amino acid identity (AAI), percentages of conserved proteins (POCP), average nucleotide identity (ANI), and alignment fraction (AF) between strain IMCC3088T and Luminiphilus syltensis NOR5-1BT were 54.5%, 47.7%, 68.0%, and 16.5%, respectively, suggesting that they belonged to different genera. Whole-genome sequencing of strain IMCC3088T revealed a 3.1 Mbp genome size with a DNA G + C content of 51.7 mol%. The genome encoded diverse metabolic pathways including sulfur oxidation, phenol degradation, and proteorhodopsin phototrophy. Mono-unsaturated fatty acids were found to be the predominant cellular fatty acid components in the strain. Phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were the primarily identified polar lipids, and ubiquinone-8 was identified as a major respiratory quinone. The taxonomic data collected herein suggested that strain IMCC3088T represented a novel genus and species of the family Halieaceae, for which the name Aequoribacter fuscus gen. nov., sp. nov. is proposed with the type strain (= KACC 15529T = NBRC 108213T).
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5.
The ambivalent role of water at the origins of life.
do Nascimento Vieira, A, Kleinermanns, K, Martin, WF, Preiner, M
FEBS letters. 2020;(17):2717-2733
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Abstract
Life as we know it would not exist without water. However, water molecules not only serve as a solvent and reactant but can also promote hydrolysis, which counteracts the formation of essential organic molecules. This conundrum constitutes one of the central issues in origin of life. Hydrolysis is an important part of energy metabolism for all living organisms but only because, inside cells, it is a controlled reaction. How could hydrolysis have been regulated under prebiotic settings? Lower water activities possibly provide an answer: geochemical sites with less free and more bound water can supply the necessary conditions for protometabolic reactions. Such conditions occur in serpentinising systems, hydrothermal sites that synthesise hydrogen gas via rock-water interactions. Here, we summarise the parallels between biotic and abiotic means of controlling hydrolysis in order to narrow the gap between biochemical and geochemical reactions and briefly outline how hydrolysis could even have played a constructive role at the origin of molecular self-organisation.
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6.
The Formation and Distribution of Modern Ooids on Great Bahama Bank.
Harris, PM, Diaz, MR, Eberli, GP
Annual review of marine science. 2019;:491-516
Abstract
Great Bahama Bank (GBB) is the principal location of the formation and accumulation of ooids (concentrically coated, sand-size carbonate grains) in the world today, and as such has been the focus of studies on all aspects of ooids for more than half a century. Our view from a close look at this vast body of literature coupled with our continuing interests stresses that biological mechanisms (microbially mediated organomineralization) are very important in the formation of ooids, whereas the controlling factor for the distribution and size of ooid sand bodies is the physical energy. Mapping and coring studies of the modern ooid sand bodies on GBB provide insight into the rock record from different perspectives. An important consequence of the dual influence of ooid formation and distribution is that the geochemical signature of ooids is not in equilibrium with the seawater in which ooids form; therefore, extracting the paleophysical energy record from oolitic deposits is potentially more accurate than doing so for the paleochemical record.
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7.
Phototrophic marine benthic microbiomes: the ecophysiology of these biological entities.
Stal, LJ, Bolhuis, H, Cretoiu, MS
Environmental microbiology. 2019;(5):1529-1551
Abstract
Phototrophic biofilms are multispecies, self-sustaining and largely closed microbial ecosystems. They form macroscopic structures such as microbial mats and stromatolites. These sunlight-driven consortia consist of a number of functional groups of microorganisms that recycle the elements internally. Particularly, the sulfur cycle is discussed in more detail as this is fundamental to marine benthic microbial communities and because recently exciting new insights have been obtained. The cycling of elements demands a tight tuning of the various metabolic processes and require cooperation between the different groups of microorganisms. This is likely achieved through cell-to-cell communication and a biological clock. Biofilms may be considered as a macroscopic biological entity with its own physiology. We review the various components of some marine phototrophic biofilms and discuss their roles in the system. The importance of extracellular polymeric substances (EPS) as the matrix for biofilm metabolism and as substrate for biofilm microorganisms is discussed. We particularly assess the importance of extracellular DNA, horizontal gene transfer and viruses for the generation of genetic diversity and innovation, and for rendering resilience to external forcing to these biological entities.
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8.
Sulfur metabolites in the pelagic ocean.
Moran, MA, Durham, BP
Nature reviews. Microbiology. 2019;(11):665-678
Abstract
Marine microorganisms play crucial roles in Earth's element cycles through the production and consumption of organic matter. One of the elements whose fate is governed by microbial activities is sulfur, an essential constituent of biomass and a crucial player in climate processes. With sulfur already being well studied in the ocean in its inorganic forms, organic sulfur compounds are emerging as important chemical links between marine phytoplankton and bacteria. The high concentration of inorganic sulfur in seawater, which can readily be reduced by phytoplankton, provides a freely available source of sulfur for biomolecule synthesis. Mechanisms such as exudation and cell lysis release these phytoplankton-derived sulfur metabolites into seawater, from which they are rapidly assimilated by marine bacteria and archaea. Energy-limited bacteria use scavenged sulfur metabolites as substrates or for the synthesis of vitamins, cofactors, signalling compounds and antibiotics. In this Review, we examine the current knowledge of sulfur metabolites released into and taken up from the marine dissolved organic matter pool by microorganisms, and the ecological links facilitated by their diversity in structures, oxidation states and chemistry.
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9.
Modelling the marine eutrophication: A review.
Ménesguen, A, Lacroix, G
The Science of the total environment. 2018;:339-354
Abstract
In the frame of a national, joint scientific appraisal, 45 scientific French-speaking experts have been mandated in 2015-2016 by the French ministries of Environment and Agriculture to perform a global review of scientific literature dealing with the eutrophication phenomenon, in freshwater as well as in marine waters. This paper summarizes the main results of this review restricted to a sub-domain, the modelling approach of the marine eutrophication. After recalling the different aims pursued, an overview is given on the historical time course of this modelling effort, its world distribution and the various tools used. Then, the main results obtained are examined, highlighting the specific strengths and weaknesses of the present models. Needs for future improvement are then listed.
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10.
Microbial ecology of deep-sea hypersaline anoxic basins.
Merlino, G, Barozzi, A, Michoud, G, Ngugi, DK, Daffonchio, D
FEMS microbiology ecology. 2018;(7)
Abstract
Deep hypersaline anoxic basins (DHABs) are unique water bodies occurring within fractures at the bottom of the sea, where the dissolution of anciently buried evaporites created dense anoxic brines that are separated by a chemocline/pycnocline from the overlying oxygenated deep-seawater column. DHABs have been described in the Gulf of Mexico, the Mediterranean Sea, the Black Sea and the Red Sea. They are characterized by prolonged historical separation of the brines from the upper water column due to lack of mixing and by extreme conditions of salinity, anoxia, and relatively high hydrostatic pressure and temperatures. Due to these combined selection factors, unique microbial assemblages thrive in these polyextreme ecosystems. The topological localization of the different taxa in the brine-seawater transition zone coupled with the metabolic interactions and niche adaptations determine the metabolic functioning and biogeochemistry of DHABs. In particular, inherent metabolic strategies accompanied by genetic adaptations have provided insights on how prokaryotic communities can adapt to salt-saturated conditions. Here, we review the current knowledge of the diversity, genomics, metabolisms and ecology of prokaryotes in DHABs.