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Abyssal manganese nodules have been explored widely for their economic potential and paleoenvironmental significance. Debate about whether biogenic or physical‐chemical processes are responsible for their formation remains because of difficulties in quantifying ancient microbiological contributions. To address this question, we investigated microbial fossils in manganese nodules from the western Pacific Ocean by integrating scanning electron microscope, transmission electron microscope, and synchrotron transmission X‐ray microscope observations. Our results suggest that the nodules host abundant fossil biogenic magnetite and manganese‐oxidizing bacteria. These organisms engage in redox reactions or live in environments with redox gradients. By combining magnetic properties and observations of fossil biogenic magnetite morphology, we estimate magnetofossil abundances and further assess fossil biogenic manganese oxide in nodules. Our results imply that manganese nodule formation appears to be dominated by biomineralization with an additional terrestrial contribution. Extensive biomineralization in ultralow‐productivity oceanic environments suggests that manganese nodule formation is an important aspect of biogeochemical cycling in abyssal seafloor environments. Key Points: Abyssal ferromanganese nodules host abundant fossil biogenic magnetite and manganese oxide produced in environments with redox gradientsRedox reactions fueled abyssal microbial activity and contributed to biomass production in microecosystems within nodulesManganese nodule formation appears to be dominated by biomineralization [ABSTRACT FROM AUTHOR]

Larval dispersal may have an important effect on genetic structure of benthic fishes. To examine the population genetic structure of spottedtail goby Synechogobius ommaturus, a 478 base pair (bp) fragment of the hypervariable portion of the mtDNA control region was sequenced and used to interpret life-history characteristics and larval dispersal strategy. Individuals ( n = 186) from 10 locations on the coasts of China and Korea were analysed and 44 haplotypes were obtained. The levels of haplotype and nucleotide diversity were higher in East China Sea populations than in other populations. Both the phylogenetic tree and the minimum spanning tree showed that no significant genealogical structures corresponding to sampling locations existed. AMOVA and pair-wise FST revealed significant genetic differentiation between populations from Korea and China. A significant isolation by distance pattern was observed in this species ( r = 0·53, P < 0·001). Both mismatch distribution analysis and neutrality tests showed S. ommaturus to have experienced a recent population expansion. These results suggest that the Pleistocene ice ages had a major effect on the phylogeographic pattern of S. ommaturus, that larvae might avoid offshore dispersal and that dispersal of larvae may maintain a migration-drift equilibrium. [ABSTRACT FROM AUTHOR]

Radioactivity levels of 210 Pb and 226 Ra were detected in a sediment core obtained using a multi-corer from the polymetallic nodule area inside the Clarion-Clipperton Zone (CCZ), a contract area of the China Ocean Mineral Resources Association (COMR) in the eastern Pacific Ocean. The profile of excess 210 Pb ( 210 Pb ex ) shows that the specific activity of 210 Pb ex has three parts with different distributions at depths of 0-16 cm (I), 17-36 cm (II), and 37-48 cm (III). When the I section of nonlocal mixing was excluded, using a steady-state diffusion mode, the bioturbation coefficients of the core were estimated to be 24.2 cm 2 /a at 17-36 cm deep and 5.9 cm 2 /a at 37-48 cm deep, which were greater compared to previously published results. This is most likely owing to bioturbations caused by various organism species in the two sections.

Oligotrophic sea area mainly distributes in tropical and subtropical ocean, which have a profound impact on the marine material cycle and the structure of biological community. Based on the comprehensive survey in M4 seamount area of the Tropical Western Pacific Ocean in August 2017, the nutrients characteristics were explained, the formation mechanism of oligotrophic characteristics in this region was explored, and the influence of M4 seamount on oligotrophic sea area was analyzed. The results showed that the M4 seamount area is a typical oligotrophic sea area. In the water column of 0-100 m, the nutrients levels are extremely low, and NO 3 -N, PO 4 -P and SiO 3 -Si are lower than 0.55, 0.15 and 1.75 μmol/L, respectively; in the water column of 100-500 m, the nutrients concentrations rise rapidly, forming nutriclines. Seawater stratification is one of the main reasons for the formation of oligotrophic characteristics in this area. The thermocline in the water column of 100-500 m and the high-salt area in the water column of 100-230 m form a dual effect, which hinders the upward transport of waters with high nutrients concentrations at the bottom. In addition, Synechococcus and bacteria grow and multiply in a large amount in the water column of 0-100 m, absorb and utilize nutrients, and aggravate the oligotrophic characteristics of this area. There are significant upwellings near the summit of the M4 seamount, which promotes the waters with high nutrients concentrations at the bottom to break through the barriers of the thermocline and high-salt area and to transport upwards into the euphotic layer, which can be better utilized by phytoplankton. This study showed that seamounts may have an important effect on improving the oligotrophic characteristics of local sea areas, and then promote the growth of phytoplankton., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nitrite is a pivotal component of the marine nitrogen cycle. The fate of nitrite determines the loss or retention of fixed nitrogen, an essential nutrient for all organisms. Loss occurs via anaerobic nitrite reduction to gases during denitrification and anammox, while retention occurs via nitrite oxidation to nitrate. Nitrite oxidation is usually represented in biogeochemical models by one kinetic parameter and one oxygen threshold, below which nitrite oxidation is set to zero. Here we find that the responses of nitrite oxidation to nitrite and oxygen concentrations vary along a redox gradient in a Pacific Ocean oxygen minimum zone, indicating niche differentiation of nitrite-oxidizing assemblages. Notably, we observe the full inhibition of nitrite oxidation by oxygen addition and nitrite oxidation coupled with nitrogen loss in the absence of oxygen consumption in samples collected from anoxic waters. Nitrite-oxidizing bacteria, including novel clades with high relative abundance in anoxic depths, were also detected in the same samples. Mechanisms corresponding to niche differentiation of nitrite-oxidizing bacteria across the redox gradient are considered. Implementing these mechanisms in biogeochemical models has a significant effect on the estimated fixed nitrogen budget.

Microplastics (MPs) contamination has been recognized as one of major threats to coastal marine environments. Although studies evidenced severe MPs contaminations to the Pacific Ocean, environmental implications of MPs concentrations, distributions, and characteristics have not been evaluated in sufficient detail. Here, we report on the distribution, abundance, and characteristics of MPs at the surface of the Northwestern Pacific Ocean, from which environmental implications are assessed. A manta trawl with a mesh size of ~330 μm and a rectangular net opening of 0.45 × 1 m was used to collect MPs samples on May 11-June 3, 2018. The MPs samples were sequentially isolated, digested, filtered, and characterized using an optical microscope, micro-Raman spectroscopy, and scanning electron microscopy. The results indicate the heterogeneity in abundance, shapes, color, and sizes of MPs. The study provides strong environmental implications such as sources, environmental degradation, residence time, transportation routes, and biological interactions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

People are increasingly aware of ubiquitous microplastic (MP) pollution in the world's ocean due to its far-reaching harmful impacts on marine ecosystem and potential hazards to human health, yet surprisingly comparatively limited studies about the abundance, source, transport, and fate of MPs in the Northwestern Pacific Ocean are available. We conducted the field survey of MPs pollution at the surface of the Northwestern Pacific Ocean between August 25 and September 26, 2017. MPs were collected from 18 sampling stations in the Northwestern Pacific Ocean using a manta trawl net with a mesh size of ∼330 μm and a rectangular net opening of 0.45 × 1 m. The abundance, shape, color, size, chemical composition, and surface morphology were characterized using light microscopy, μ-Raman spectroscopy, and scanning electron microscopy (SEM). The results show surface MPs at concentrations ranging over two orders of magnitude (6.4 × 10 2 to 4.2 × 10 4 particles km -2 ) and a mean abundance of 1.0 × 10 4 particles km -2 . The most concentrated MPs were found at XTJ3-9, which may be associated with the convergence of surface currents collectively affected by the Kuroshio and its extension, adjacent eddies, and flow regimes. Polyethylene accounts for 57.8% of enumerated MPs, followed by polypropylene (36.0%) and nylon (3.4%). Pellets, sheets, lines, and films are major forms which may be linked to the breakdown of larger particles, aging processes, and movement over long distances by prevailing currents. Four possible MPs migration pathways were proposed based on the source-specific distribution, chemical fingerprints, size distribution patterns, and the observed physical oceanographic parameters., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Five new fungal hybrid polyketides, cladosins A-D (1-4), that contain a novel linear 6(3)-enamino-8,10-dihydroxy-tetraketide (1 and 2) or 6-enamino-7(8)-en-10-ol (3 and 4) moiety, as well as the biogenetically related cladosin E (5), were isolated from the deep-sea-derived fungus Cladosporium sphaerospermum 2005-01-E3. Their structures (1-5) were elucidated through a combination of spectroscopic data, chemical conversion, and both Mosher's and Marfey's methods for stereochemical assignment. A plausible biogenetic pathway to 1-5 is proposed. Cladosin C (3) possesses mild anti-influenza A H1N1 virus activity.