Microbial Diversity of Deep-Sea Ferromanganese Crust Field in the Rio Grande Rise, Southwestern Atlantic Ocean.

Seamounts are often covered with Fe and Mn oxides, known as ferromanganese (Fe-Mn) crusts. Future mining of these crusts is predicted to have significant effects on biodiversity in mined areas. Although microorganisms have been reported on Fe-Mn crusts, little is known about the role of crusts in shaping microbial communities. Here, we investigated microbial communities based on 16S rRNA gene sequences retrieved from Fe-Mn crusts, coral skeleton, calcarenite, and biofilm at crusts of the Rio Grande Rise (RGR). RGR is a prominent topographic feature in the deep southwestern Atlantic Ocean with Fe-Mn crusts. Our results revealed that crust field of the RGR harbors a usual deep-sea microbiome. No differences were observed on microbial community diversity among Fe-Mn substrates. Bacterial and archaeal groups related to oxidation of nitrogen compounds, such as Nitrospirae, Nitrospinae phyla, Candidatus Nitrosopumilus within Thaumarchaeota group, were present on those substrates. Additionally, we detected abundant assemblages belonging to methane oxidation, i.e., Methylomirabilales (NC10) and SAR324 (Deltaproteobacteria). The chemolithoautotrophs associated with ammonia-oxidizing archaea and nitrite-oxidizing bacteria potentially play an important role as primary producers in the Fe-Mn substrates from RGR. These results provide the first insights into the microbial diversity and potential ecological processes in Fe-Mn substrates from the Atlantic Ocean. This may also support draft regulations for deep-sea mining in the region.

Aliterella atlantica gen. nov., sp. nov., and Aliterella antarctica sp. nov., novel members of coccoid Cyanobacteria.

Two Cyanobacteria isolated from South Atlantic Ocean continental shelf deep water and from a marine green algae inhabiting the Admiralty Bay, King George Island, Antarctica were investigated based on morphological and ultrastructural traits, phylogeny of 16S rRNA gene sequences, secondary structure of the 16S-23S internal transcribed spacer regions and phylogenomic analyses. The majority of these evaluations demonstrated that both strains differ from the genera of cyanobacteria with validly published names and, therefore, supported the description of the novel genus as Aliterella gen. nov. The identity and phylogeny of 16S rRNA gene sequences, together with the secondary structure of D1D1' and BoxB intergenic regions, further supported the two strains representing distinct species: Aliterella atlantica gen. nov., sp. nov. (type SP469036, strain CENA595T) and Aliterella antarctica sp. nov. (type SP469035, strain CENA408T). The phylogenomic analysis of A. atlantica sp. nov. CENA595T, based on 21 protein sequences, revealed that this genus belongs to the cyanobacterial order Chroococcidiopsidales. The isolation and cultivation of two geographically distant unicellular members of a novel cyanobacterial genus and the sequenced genome of the type strain bring new insights into the current classification of the coccoid group, and into the reconstruction of their evolutionary history.

Diel Vertical Dynamics of Gelatinous Zooplankton (Cnidaria, Ctenophora and Thaliacea) in a Subtropical Stratified Ecosystem (South Brazilian Bight).

The diel vertical dynamics of gelatinous zooplankton in physically stratified conditions over the 100-m isobath (~110 km offshore) in the South Brazilian Bight (26°45'S; 47°33'W) and the relationship to hydrography and food availability were analyzed by sampling every six hours over two consecutive days. Zooplankton samples were taken in three depth strata, following the vertical structure of the water column, with cold waters between 17 and 13.1°C, influenced by the South Atlantic Central Water (SACW) in the lower layer (>70 m); warm (>20°C) Tropical Water in the upper 40 m; and an intermediate thermocline with a deep chlorophyll-a maximum layer (0.3-0.6 mg m-3). Two distinct general patterns were observed, emphasizing the role of (i) physical and (ii) biological processes: (i) a strong influence of the vertical stratification, with most zooplankton absent or little abundant in the lower layer. The influence of the cold SACW on the bottom layer apparently restricted the vertical occupation of most species, which typically inhabit epipelagic warm waters. Even among migratory species, only a few (Aglaura hemistoma, Abylopsis tetragona eudoxids, Beroe sp., Thalia democratica, Salpa fusiformis) crossed the thermocline and reached the bottom layer. (ii) A general tendency of partial migrations, with variable intensity depending on the different species and developmental stages; populations tended to be more widely distributed through the water column during daylight, and to become more aggregated in the upper layer during the night, which can be explained based on the idea of the "hunger-satiation hypothesis", maximizing feeding and minimizing the chances of being predated.

Offshore distribution patterns of the cyanobacterium Trichodesmium erythraeum ehrenberg and associated phyto- and bacterioplankton in the southern Atlantic coast ( Paraná, Brazil )

O propósito principal da presente pesquisa foi investigar as florações de Trichodesmium erythraeum na plataforma continental interna do Estado do Paraná, Brasil. Foram medidas, em águas de superfície a temperatura, salinidade, bactérias totais, biomassa bacteriana, clorofila-a, densidade fitoplanctônica, densidade das cianobactérias Anabaena sp., Merismopedia sp. e T. erythraeum. Ao contrário dos dinoflagelados, cuja abundância foi relativamente constante em todas as estações, as diatomáceas cêntricas e penadas, Anabaena sp. e Merismopedia sp. foram mais abundantes até a isóbata dos 15 m. A densidade de bactérias totais também foi relativamente homogênea na área amostrada, o que sugere que as florações de T. erythraeum não se encontravam em fase senescente. Os resultados confirmam que T. erythraeum é capaz de sobreviver em condições ambientais relativamente inóspitas devido à sua capacidade de fixar nitrogênio e efetuar a fotossíntese em altas intensidades de luz.