Sequencing surveys of microbial communities in marine subsurface sediments have focused on organic-rich, continental margins; the database for organic-lean deep-sea sediments from mid-ocean regions is underdeveloped. The archaeal community in subsurface sediments of ODP Site 1225 in the eastern equatorial Pacific (3760 m water depth; 1.1 and 7.8 m sediment depth) was analyzed by PCR, cloning an...

The South China Sea (SCS) is the largest marginal sea of the western Pacific Ocean, yet little is known about archaeal distributions and TEX₈₆-based temperatures in this unique oceanic setting. Here we report findings of abundances in both core lipids (CL) and intact polar lipids (IPL) of Archaea from surface water (CL only) and core-top sediments from different regions of the SCS. TEX₈₆-derive...

Measurements of Pa, Th and Th concentrations have been made on five water-column profiles along the western margin of the Madagascar and Mascarene Basins in the southern Indian Ocean. These measurements help to fill a significant gap in the global coverage of water-column Th, Th and Pa data. Th concentrations vary, but generally increase with depth, suggesting higher particle loading in deeper ...

Iron reduction in subseafloor sulfate-depleted and methane-rich marine sediments is currently a subject of interest in subsurface geomicrobiology. While iron reduction and microorganisms involved have been well studied in marine surface sediments, little is known about microorganisms responsible for iron reduction in deep methanic sediments. Here, we used quantitative PCR-based 16S rRNA gene co...

A hybrid method coupling nonlinear and linear propagation codes is used to study the nonlinear signature of long-range acoustic propagation for high-amplitude sources in an ocean waveguide. The differences between linear and nonlinear propagation are investigated in deep and shallow water environments. The spectral reshaping that occurs in nonlinear propagation induces two main effects: in shal...

Here we describe a new reaction-transport model that quantitatively examines δ13C profiles of porewater methane and dissolved inorganic carbon (DIC) (δCCH4 and δCDIC) in the anoxic sediments of the Santa Barbara Basin (California Borderland region). Best-fit solutions of the model to these data suggest that CO2 reduction is the predominant form of methanogenesis in these sediments. These soluti...

Polycyclic aromatic hydrocarbons (PAHs) are widespread in marine ecosystems and originate from natural sources and anthropogenic activities. PAHs enter the marine environment in two main ways, corresponding to chronic pollution or acute pollution by oil spills. The global PAH fluxes in marine environments are controlled by the microbial degradation and the biological pump, which plays a role in...

determined from the downward vertical flux of pheopigments. Improved extraction of chlorophyll a and b from algae using dimethylsulfoxide. Limnol. zooplankton reproduction: Implications for diel vertical migration theory. Abstract-We report the first seasonal time-series observations of porewater composition obtained for deep-sea sediments. We observed considerable temporal variability of O,, N...

The deep ocean floor covers more than 60% of the Earth's surface, and hosts diverse bacterial communities with important functions in carbon and nutrient cycles. The identification of key bacterial members remains a challenge and their patterns of distribution in seafloor sediment yet remain poorly described. Previous studies were either regionally restricted or included few deep-sea sediments,...