Microbial communities in sponges, Antarctica
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Genetic techniques were employed to investigate the archaeal, bacterial and eukaryotic communities associated with the Antarctic sponges Kirkpatrickia varialosa, Latrunculia apicalis, Homaxinella balfourensis, Mycale acerata and Sphaerotylus antarcticus. The sponges and seawater for the analyses were obtained from sites in McMurdo Sound: adjacent to McMurdo Station (MM), Scott Base (SB) and Cape Armitage (CA).Rarefaction analysis was performed to determine the number of unique bacterial clones as a proportion of the estimated total diversity.Archaeal PCR product was not detected from seawater, H. balfourensis or S. antarcticus samples. 150 archaeal clones (50 each from L. apicalis, K. varialosa, and M. acerata ) were screened by RFLP analysis, 4 unique operational taxonomic units (OTUs) wre observed. RFLP analysis screened 250 sponge-derived bacterial clones, 61 were unique OTUs not detected during examination of 160 seawater-derived clones and were subsequently sequenced for phylogenetic determination. Of the 160 seawater bacterial clones, 103 exhibited unique banding patterns, creating distinct seawater operational taxonomic units (OTUs).The phylogenetic affiliation of sponge-derived bacteria was assessed by 16S rRNA sequencing of cloned DNA fragments. Denaturing gradient gel electrophoresis (DGGE) was used to determine the profiles of 18S rRNA-defined eukaryotic populations from replicate sponge specimens at the 3 Antarctic sites. Samples analysed by DGGE were K. varialosa (K), L. apicalis (L), M. acerata (M) and seawater (SW). 2-4 replicates were used per sample type.Neighbour-joining phylogenetic trees were formed from analysis of: 889 bp of 16S rRNA gene sequence from Antarctic archaeal clones 1-4; 857 bp of 16S rRNA gene sequence from Antarctic bacterial clones; and 304 bp of bacterial 16S rRNA gene sequence retrieved from DGGE. Branches were also found using the Fitch-Margoliash or maximum parsimony methods.The bacterial communities associated with Antarctic sponges primarily clustered within the Gamma and Alpha proteobacteria and the Cytophaga/Flavobacterium of Bacteroidetes group.GenBank Accession Numbers were assigned to: 4 unique Antarctic archaeal sequences detected in M. acerata (AY320198, AY320199, AY320200, AY320201). The study aimed to describe the microbial species composition, the stability of the host-bacterium associations and the spatial variability in sponge-derived microbial communities. 54 sponge-derived unique bacterial clones which produced suitable sequence data for phylogenetic analysis, GenBank Accession Numbers in brackets (AY321378, AY321379, AY321380, AY321381, AY321382, AY321383, AY321384, AY321385, AY321386, AY321387, AY321388, AY321389, AY321390, AY321391, AY321392, AY321393, AY321394, AY321395, AY321396, AY321397, AY321398, AY321399, AY321400, AY321401, AY321402, AY321403, AY321404, AY321405, AY321406, AY321407, AY321408, AY321409, AY321410, AY321411, AY321412, AY321413, AY321414, AY321415, AY321416, AY321417, AY321418, AY321419, AY321420, AY321421, AY321422, AY321423, AY321424, AY321425, AY321426, AY321427, AY321428, AY321429, AY321430, AY321431, AY321432); 10 bands for which high quality eukaryotic sequence data was obtained (AY320202, AY320203, AY320204, AY320205, AY320206, AY320207, AY320208, AY320209, AY320210, AY320211); and high-quality sequences for 19 bacterial bands (AY320212, AY320213, AY320214, AY320215, AY320216, AY320217, AY320218, AY320219, AY320220, AY320221, AY320222, AY320223, AY320224, AY320225, AY320226, AY320227, AY320228, AY320229, AY320230).
Spring Phytoplankton Assemblages in the Southern Ocean Between Australia and Antarctica
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This dataset comprises of an excel spreadsheet of data collected on the CLIVAR-SR3 cruise in November to December 2001. The spreadsheet contains plankton and carbon data. From the abstract of the referenced publication: Variations of phytoplankton assemblages were studied in November-December 2001, in surface waters of the Southern Ocean along a transect between the Sub-Antarctic Zone (SAZ) and the Seasonal Ice Zone (SIZ; 46.9-64.9 degrees S; 142-143 degrees E; CLIVAR-SR3 cruise). Two regions had characteristic but different phytoplankton assemblages. Nanoflagellates (less than 20 microns) and pico-plankton (~2 microns) occurred in similar concentrations along the transect, but were dominant in the SAZ, Sub-Antarctic Front (SAF), Polar Front Zone (PFZ) and the Inter-Polar Front Zone (IPFZ), (46.9-56.9 degrees S). Along the entire transect their average cell numbers in the upper 70 m of water column, varied from 300,000 to 1,100,000 cells per litre. Larger cells (greater than 20 microns), diatoms and dinoflagellates, were more abundant in the Antarctic Zone-South (AZ-S) and the SIZ (60.9-64.9 degrees S). In AZ-S and SIZ diatoms ranged between 270,000 and 1,200,000 cells per litre, dinoflagellates from 31,000 to 102,000 cells per litre. A diatom bloom was in progress in the AZ-S showing a peak of 1,800,000 cells per litre. Diatoms were dominated by Pseudo-nitzschia spp., Fragilariopsis spp., and Chaetoceros spp. Pseudo-nitzschia spp. outnumbered other diatoms in the AZ-S. Fragilariopsis spp. were most numerous in the SIZ. Dinoflagellates contained autotrophs (eg Prorocentrum) and heterotrophs (Gyrodinium/Gymnodinium, Protoperidinium). Diatoms and dinoflagellates contributed most to the cellular carbon: 11-25 and 17-124 micrograms of carbon per litre, respectively. Small cells dominated in the northern region characterised by the lowest N-uptake and new production of the transect. Larger diatom cells were prevalent in the southern area with higher values of N-uptake and new production. Diatom and nanoflagellate cellular carbon contents were highly correlated with one another, with primary production, and productivity related parameters. They contributed up to 75% to the total autotrophic C biomass. Diatom carbon content was significantly correlated to nitrate uptake and particle export, but not to ammonium uptake, while flagellate carbon was well correlated to ammonium uptake, but not to export. Diatoms have contributed highly to particle export along the latitudinal transect, while flagellates played a minor role in the export. This work was completed as part of ASAC project 1343 (ASAC_1343). The fields in this dataset are: Station (depth, position, date, comments) Species Cells per millilitre cell carbon - micrograms per litre