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Coccolithophores are a key functional phytoplankton group and produce minute calcite plates (coccoliths) in the sunlit layer of the pelagic ocean. Coccoliths significantly contribute to the sediment record since the Triassic and their geometry have been subject to palaeoceanographic and biological studies to retrieve information on past environmental conditions. Here, we present a comprehensive analysis of coccolith, coccosphere and cell volume data of the Southern Ocean Emiliania huxleyi ecotype A, subject to gradients of temperature, irradiance, carbonate chemistry and macronutrient limitation. All tested environmental drivers significantly affect coccosphere, coccolith and cell volume with driver‐specific sensitivities. However, a highly significant correlation emerged between cell and coccolith volume with Vcoccolith = 0.012 ± 0.001 * Vcell + 0.234 ± 0.066 (n = 23, r2 =.85, p <.0001, σest = 0.127), indicating a primary control of coccolith volume by physiological modulated changes in cell volume. We discuss the possible application of fossil coccolith volume as an indicator for cell volume/size and growth rate and, additionally, illustrate that macronutrient limitation of phosphorus and nitrogen has the predominant influence on coccolith volume in respect to other environmental drivers. Our results provide a solid basis for the application of coccolith volume and geometry as a palaeo‐proxy and shed light on the underlying physiological reasons, offering a valuable tool to investigate the fossil record of the coccolithophore E. huxleyi. [ABSTRACT FROM AUTHOR]

Here we described the general hydrography in the South Brazil Bight (23–28°S) with emphasis on frontal processes and their role in the structure and functioning of the regional shelf ecosystem. One of the key roles of fronts for ecosystem dynamics is the injection of nutrients into the euphotic zone increasing primary production. Frontal systems also affect plankton biodiversity and fisheries. Physical mechanisms behind frontogenesis in this region are similar in the analogous western side of oceanic basins; their magnitude and seasonal dynamics, however, may differ due to peculiarities in shelf morphology, wind field, tidal circulation and continental drainage. Here we provide a reassessment of earlier and recent ecological and hydrographic studies for a better evaluation of the spatial and temporal dynamics of fronts and their regional ecological implications. Albeit in a fragmented manner, we give a more detailed conceptual framework about the ecosystem responses to the complex frontal system in the South Brazil Bight. [ABSTRACT FROM AUTHOR]

Five oceanographic cruises were made between November 2005 and June 2006, sampling a cross-shelf transect off the South Brazilian Bight (SBB; 26°46′S) to follow the seasonal development of the South Atlantic Central Water (SACW) intrusion over the shelf and its influence on the assemblage of planktonic cnidarians. An onshore wind-driven bottom intrusion of the SACW was clearly perceptible, reaching the coast in January. From March onward, the SACW influence was gradually displaced seaward due to wind and tidal mixing. By late June the SACW influence was offshore and the inshore was dominated by low-salinity waters (<34.5). The abundance, distribution, and general taxonomic composition of both medusae and siphonophores were strongly influenced by the onshore intrusion of the SACW. An inshore–offshore gradient was clear. The Canonical Correspondence Analysis suggested that coastal species – dominated by Liriope tetraphylla , actinula larvae and Muggiaea kochi – were mostly related to food availability and a vertically mixed environment inshore, and their abundance and extent were reduced during intrusion periods. In contrast, species with offshore affinities tended to increase their abundance and distribution during intrusion periods, and were mostly related to the presence of thermal stratification and a deep chlorophyll maximum layer. Most of these offshore species, such as Aglaura hemistoma , Rhopalonema velatum and many calycophorans, are associated with the warm upper layer. However, high concentrations of large (>20 mm in diameter) Solmaris corona were observed exclusively in cold waters, suggesting this medusa is a SACW indicator. [ABSTRACT FROM AUTHOR]

Describes the seasonal pattern of periphytic diatom populations growing on glass slides in the Bay of Paranagua, southern Brazil in relation to environmental parameters. Variation of temperature, salinity and precipitation and Secchi readings during high and low tides at surface and bottom layers in the water column; Diatom species colonizing glass slides in the bay; Photosynthetic rate and biomass accumulation.

The article refers to phytoplankton biomass. Phytoplankton biomass and photosynthesis were investigated in relation to physicochemical environmental conditions in Tokyo Bay from May 1979 through March 1981. Vertical and seasonal variations of "chlorophyll a," photosynthetic and respiratory activity, and environmental conditions were investigated in the inner part of the bay. It is found that "Chlorophyll a" concentrations were generally high when salinity was low, but no definite relationship was observed between photosynthesis and salinity. No clear relationship was observed between chlorophyll a and nutrient concentrations.

• Rio Grande Rise pelagic microbiome. • Picoplankton abundance. • Dominance of heterotrophic bacteria. Marine microbes control the flux of matter and energy essential for life in the oceans. Until now, the distribution and diversity of planktonic microorganisms above Fe-Mn crusts have received relatively little attention. Future deep-sea mining is predicted to affect microbial diversity. Here, we studied the ecology of picoplankton among pelagic zones of a Fe-Mn deposit region, at Rio Grande Rise, Southwestern Atlantic Ocean. We investigated microbial community composition using high-throughput sequencing of 16S rRNA genes and their abundance estimated by flow cytometry. The picoplankton populations were more abundant in epi- and mesopelagic waters, corresponding to the Tropical and South Atlantic Central Water masses. Bacterial groups related to heterotrophy, such as Oceanospirillales (Gammapoteobacteria), SAR11 (Alphapoteobacteria), Flavobacteriales (Bacteroida), and Rhodobacterales (Alphapoteobacteria), were the main representatives of the pelagic microbial community. Additionally, we detected abundant assemblages belonging to acetate-oxidizing manganese reducers, i.e., Alteromona s. No differences were observed in microbial community diversity among pelagic zones and water masses. These results provide the first insights into the picoplankton abundance, taxonomy and diversity, and ecological processes in the Rio Grande Rise of the Atlantic Ocean. This may also support draft regulations for deep-sea mining in the region. [ABSTRACT FROM AUTHOR]