The Amundsen Sea Polynya is characterized by large phytoplankton blooms, which makes this region disproportionately important relative to its size for the biogeochemistry of the Southern Ocean. In situ data on phytoplankton are limited, which is problematic given recent reports of sustained change in the Amundsen Sea. During two field expeditions to the Amundsen Sea during austral summer 2010–2...

The diversity of macro-organisms increases towards the equator, with almost no exceptions. It is the most conserved biogeographical pattern on earth and is thought to be related to the increase of temperature and productivity in the tropics. The extent and orientation of a latitudinal gradient of marine bacterioplankton diversity is controversial. Here we studied the euphotic zone of the Atlant...

Attenuation of light and sound propagation in the upper ocean is tightly linked to the patterns of vertical distribution of particulate matter (primarily detritus, phytoplankton, and zooplankton). Local maxima in these distributions frequently occur within the euphotic zone, and are often concentrated within depth intervals that are less than 1-2m thick (e.g., Dekshenieks et al. 2001, Cowles 20...

[1] The effects of physical processes on the distribution, speciation, and sources/sinks for Fe in a high-nutrient low-chlorophyll (HNLC) region were assessed during FeCycle, a mesoscale SF6 tracer release during February 2003 (austral summer) to the SE of New Zealand. Physical mixing processes were prevalent during FeCycle with rapid patch growth (strain rate g = 0.17–0.20 d ) from a circular ...

Heterotrophic activities on sinking particulate matter (SPM) play an important role in SPM fluxes in the ocean. To demonstrate regional differences in heterotrophic activities on SPM, we measured heterotrophic bacterial production (HBP) in seawater (HBP(SW)) and SPM (HBP(SPM)) as well as potential extracellular enzyme activity (EEA) in SPM on a transect along 155°E in the western North Pacific ...

We independently manipulated mixing intensity (strong artificial mixing vs. background turbulence) and water-column depth (2 m, 4 m, 8 m, and 12 m) in order to explore their separate and combined effects in a field enclosure experiment. To accentuate the vertical light gradient, enclosures had black walls, resulting in a euphotic depth of only 3.7 m. All enclosures were placed in a well-mixed w...

Using current, hydrographic and satellite observations collected off Northeast Brazil around the Fernando de Noronha Archipelago Rocas Atoll during two oceanographic cruises (spring 2015 fall 2017), we investigated general oceanic circulation its modifications induced by islands. In spring 2015, area was characterized lower SST (26.6°C) deep mixed-layer (∼90 m). At this depth, a strong current ...

Traditional measurements of the Secchi depth ( z SD ) and Forel-Ule colour were collected alongside modern radiometric ocean clarity colour, in-situ chlorophyll-a concentration (Chl-a), on four Atlantic Meridional Transect (AMT) cruises. These data used to evaluate historic optical techniques for monitoring Chl-a, remote-sensing algorithms. Historic broadly consistent with current understanding...

Sinking aggregates are the major component of the vertical particulate flux in most regions of the ocean. Controlling factors for aggregate remineralization rates and solute exchange with the surrounding water, however, are poorly quantified because of few empirical data. To study the role of flow and diffusion on aggregate remineralization rates, oxygen distributions were mapped within and aro...