1,721,671 research outputs found
Benthic prokaryotic community dynamics along the Ardencaple Canyon, Western Greenland Sea
No full textThe Ardencaple Canyon, emanating from the Eastern Greenland continental rise over a distance of about 200 km towards the Greenland Basin, was investigated to determine the effect of enhanced down-slope transport mechanisms on deep-sea benthic prokaryotic communities. The concentration of viable bacterial cells (Live/Dead (R) BacLight) and prokaryotic incorporation rates (H-3-thymidine, C-14-leucine) increased with increasing distance from the continental shelf. Multidimensional scaling (MDS) results from terminal restriction fragment length polymorphism (T-RFLP) analysis indicated a spatial coherence between the benthic bacterial community structure, prokaryotic incorporation rates, water content, protein concentration and the total organic matter in the sediments. The community complexity in sediments at 4-5 cm depth was lower in the central parts of the channel compared with the northern and the southern levees, while richness in surface sediments of all stations was similar. Lacking any clear indications for a recent mass sediment transport or funneled shelf drainage flows, high similarities between bacterial assemblages in sediments along the canyon course may thus be governed by a combination of an ice-edge induced particle flux, episodic down-slope and canyon-guided transport mechanisms. (C) 2011 Elsevier B.V. All rights reserved
Soft-walled monothalamous and Nodellum-like foraminifera and gromiids (Protista) at the Håkon-Mosby Mud Volcano (Barents Sea slope)
No full textWe describe the occurrence of basal (‘primitive’) foraminifera and gromiids (a distinct taxon related to the foraminifera) in different bathyal habitats of the Håkon Mosby Mud Volcano (HMMV, Barents Sea). The foraminifera include two distinct groupings: (1) soft-shelled monothalamous foraminifera (‘allogromiids’, ‘saccamminids’ and ‘psammosphaerids’) and (2) brown organic-walled foraminifera (genera Conicotheca, Nodellum, Placopsilinella and Resigella). Samples were analysed from (1) the ‘hot centre’ of the volcano where fluid upflow was maximal; (2) smooth and structured muds in a ‘warm’ area of the centre where fluid upflow was reduced; (3) areas covered by Beggiatoa mats; (4) an area colonised by siboglinid polychaetes (‘pogonophores’); and (5) areas of ‘normal’ seafloor outside the volcano. Together, the studied organisms represented 57.8 % (‘normal’ seafloor; n?=?418), 28.5 % (‘warm centre’; n?=?122), and 26.4 % (Beggiatoa mats; n?=?5) of all ‘live’ (stained) foraminifera in three samples (0–1 cm layer) that were sorted for all stained foraminifera. In total, the 17 samples examined yielded 21 ‘allogromiid’ (organic-walled), 25 ‘saccamminid’ (agglutinated) and 5 other morphospecies among the monothalamous foraminifera, as well as 5 ‘brown-walled’ and 5 gromiid morphospecies. Four taxa were identified to species (Conicotheca nigrans, Resigella moniliforme, R. polaris, Micrometula hyalinosphaera); another seven were assigned to the genera Bathyallogromia, Conqueria, Nodellum, Placopsilinella, Resigella, Tinogullmia and Vanhoeffenella. All others were undescibed at the genus level. Some species, notably ‘Saccamminid sp. 5’, C. nigrans and Nodellum sp., were distributed in sediment layers down to 5 cm depth, and sausage-shaped gromiids were also present in the deeper layers of some samples. The number of basal foraminiferal and gromiid morphospecies varied considerably from site to site. It was relatively high north of the volcano (42 morphospecies in 4 samples) and in the ‘warm centre’ (28 morphospecies in 2 samples), somewhat lower southwest of the volcano (at least 13 morphospecies in 2 samples) and in the siboglinid field (14 morphospecies in three samples), and substantially reduced in the bacterial mat area (5 morphospecies in 6 samples). The scarcity of these protists at the bacterial mat sites is probably a consequence of high sulfide concentrations. No stained foraminifera or gromiids were observed at the ‘hot centre’ site. In general, assemblages from within and around the HMMV resembled those reported from other bathyal sites, notably in the Porcupine Seabight. Saccamminid sp. 5, by far the most common species in our samples, belongs to a ‘lamp-like’ morphotype that is widely distributed in the oceans. The wall structure, and the presence of what appears to be an internal partition across the base of the neck, is reminiscent of some komokiaceans
The organic-walled genera Resigella and Conicotheca (Protista, Foraminifera) at two Arctic deep-sea sites (North Pole and Barents Sea), including the description of a new species of Resigella
No full textWe describe a new organic-walled foraminiferan species from the central Arctic Ocean (North Pole; 4,300 m water depth) and the Håkon Mosby Mud Volcano (HMMV) at the south-western Barents Sea continental margin (1,250 m depth) based on morphological features. Resigella polaris sp. nov. has a more or less transparent test, brownish-yellow in colour, less than 200?µm in length, with a length:width ratio of 3.1–4.7, and consisting of 3 droplet-shaped to oval chambers. Morphologically, it is intermediate between R. bilocularis and R. laevis, two species described from an extreme hadal site (Challenger Deep, 10,895 m depth) in the western Pacific Ocean. Another species present at the HMMV is R. moniliforme, the type species of Resigella, which has only been reported once from outside the Pacific. Additionally, our Arctic samples yielded a species of the diminutive, monothalamous, organic-walled genus Conicotheca that is remarkably similar to C. nigrans from the Challenger Deep, despite the considerable geographical and bathymetric gulf between the populations. The abundance of these species, and particularly of R. polaris sp. nov. at the North Pole, probably reflects the oligotrophic character of this ice-covered region
Raw data of continuous VM-ADCP (vessel-mounted Acoustic Doppler Current Profiler) profile during POLARSTERN cruise ARK-XXV-2
No full textMeiofauna communities from iron-enriched sediments at LTER HAUSGARTEN, with special foucs on nematodes
No full textImpact of Local Iron Enrichment on the Small Benthic Biota in the deep Arctic Ocean The study assesses the impact of local iron enrichment on the small benthic biota (bacteria, meiofauna) together with environmental parameters indicating the input of food at the deep seafloor. To evaluate the hypothesis that abundance, distribution, and diversity of the small benthic biota varies in relation to a local input of structural steel at the seabed, we analyzed sediment samples and the associated infauna along a short transect with increasing distance to an iron source, i.e., corroding steel weights of a free-falling observational platform (bottom-lander), lying on the seafloor for approximately seven years. Iron-enriched surface sediments in the vicinity of the bottom-weight left in summer 2008 after a short-term deployment of a bottom-lander in 2433 m water depth at the LTER (Long-Term Ecological Research) observation HAUSGARTEN in eastern parts of the Fram Strait were sampled on 28th July 2015 using push-corer (PC) handled by the Remotely Operated Vehicle (ROV) QUEST 4000 (MARUM Center for Marine Environmental Sciences, Germany) during Dive 369 from board RV Polarstern. The block-shaped steel bottom-weights (30 x 30 x 6 cm) were sitting about half of the height sunken into the seafloor and thus, almost not affecting near-bottom currents. During sampling in 2015, the plates were largely corroded. Surface sediments around the plates had an orange-red color with a gradient of decreasing color intensity with increasing distance from the source, i.e., the bottom weight. A total of eight push-corer samples (PC1-8) were taken at approx. regular distances (on average every 18 cm) along a short transect (about 1.5 m) crossing the iron gradient. Push-corers PC1-4 retrieved sediment from heavily impacted sediments, while samples taken from push-corers PC5-8 were visually indistinguishable from background sediments in the wider area. After recovery of the ROV, sediment cores (8 cm in diameter, and 20-25 cm in height) were sub-sampled using plastic syringes with cut-off anterior ends for meiofauna and nematode communities as well as for environmental parameters. The position specified in the data sets (longitude / latitude) refers to the position of the ROV
Environmental parameters of iron-enriched sediments at LTER HAUSGARTEN during POLARSTERN cruise PS93
No full textImpact of Local Iron Enrichment on the Small Benthic Biota in the deep Arctic Ocean The study assesses the impact of local iron enrichment on the small benthic biota (bacteria, meiofauna) together with environmental parameters indicating the input of food at the deep seafloor. To evaluate the hypothesis that abundance, distribution, and diversity of the small benthic biota varies in relation to a local input of structural steel at the seabed, we analyzed sediment samples and the associated infauna along a short transect with increasing distance to an iron source, i.e., corroding steel weights of a free-falling observational platform (bottom-lander), lying on the seafloor for approximately seven years. Iron-enriched surface sediments in the vicinity of the bottom-weight left in summer 2008 after a short-term deployment of a bottom-lander in 2433 m water depth at the LTER (Long-Term Ecological Research) observation HAUSGARTEN in eastern parts of the Fram Strait were sampled on 28th July 2015 using push-corer (PC) handled by the Remotely Operated Vehicle (ROV) QUEST 4000 (MARUM Center for Marine Environmental Sciences, Germany) during Dive 369 from board RV Polarstern. The block-shaped steel bottom-weights (30 x 30 x 6 cm) were sitting about half of the height sunken into the seafloor and thus, almost not affecting near-bottom currents. During sampling in 2015, the plates were largely corroded. Surface sediments around the plates had an orange-red color with a gradient of decreasing color intensity with increasing distance from the source, i.e., the bottom weight. A total of eight push-corer samples (PC1-8) were taken at approx. regular distances (on average every 18 cm) along a short transect (about 1.5 m) crossing the iron gradient. Push-corers PC1-4 retrieved sediment from heavily impacted sediments, while samples taken from push-corers PC5-8 were visually indistinguishable from background sediments in the wider area. After recovery of the ROV, sediment cores (8 cm in diameter, and 20-25 cm in height) were sub-sampled using plastic syringes with cut-off anterior ends for meiofauna and nematode communities as well as for environmental parameters. The position specified in the data sets (longitude / latitude) refers to the position of the ROV
Meiofauna communities from iron-enriched sediments at LTER HAUSGARTEN during POLARSTERN cruise PS93
No full textImpact of Local Iron Enrichment on the Small Benthic Biota in the deep Arctic Ocean The study assesses the impact of local iron enrichment on the small benthic biota (bacteria, meiofauna) together with environmental parameters indicating the input of food at the deep seafloor. To evaluate the hypothesis that abundance, distribution, and diversity of the small benthic biota varies in relation to a local input of structural steel at the seabed, we analyzed sediment samples and the associated infauna along a short transect with increasing distance to an iron source, i.e., corroding steel weights of a free-falling observational platform (bottom-lander), lying on the seafloor for approximately seven years. Iron-enriched surface sediments in the vicinity of the bottom-weight left in summer 2008 after a short-term deployment of a bottom-lander in 2433 m water depth at the LTER (Long-Term Ecological Research) observation HAUSGARTEN in eastern parts of the Fram Strait were sampled on 28th July 2015 using push-corer (PC) handled by the Remotely Operated Vehicle (ROV) QUEST 4000 (MARUM Center for Marine Environmental Sciences, Germany) during Dive 369 from board RV Polarstern. The block-shaped steel bottom-weights (30 x 30 x 6 cm) were sitting about half of the height sunken into the seafloor and thus, almost not affecting near-bottom currents. During sampling in 2015, the plates were largely corroded. Surface sediments around the plates had an orange-red color with a gradient of decreasing color intensity with increasing distance from the source, i.e., the bottom weight. A total of eight push-corer samples (PC1-8) were taken at approx. regular distances (on average every 18 cm) along a short transect (about 1.5 m) crossing the iron gradient. Push-corers PC1-4 retrieved sediment from heavily impacted sediments, while samples taken from push-corers PC5-8 were visually indistinguishable from background sediments in the wider area. After recovery of the ROV, sediment cores (8 cm in diameter, and 20-25 cm in height) were sub-sampled using plastic syringes with cut-off anterior ends for meiofauna and nematode communities as well as for environmental parameters. The position specified in the data sets (longitude / latitude) refers to the position of the ROV
Nematoda abundance and biomass from iron-enriched sediments at LTER HAUSGARTEN during POLARSTERN cruise PS93
No full textImpact of Local Iron Enrichment on the Small Benthic Biota in the deep Arctic Ocean The study assesses the impact of local iron enrichment on the small benthic biota (bacteria, meiofauna) together with environmental parameters indicating the input of food at the deep seafloor. To evaluate the hypothesis that abundance, distribution, and diversity of the small benthic biota varies in relation to a local input of structural steel at the seabed, we analyzed sediment samples and the associated infauna along a short transect with increasing distance to an iron source, i.e., corroding steel weights of a free-falling observational platform (bottom-lander), lying on the seafloor for approximately seven years. Iron-enriched surface sediments in the vicinity of the bottom-weight left in summer 2008 after a short-term deployment of a bottom-lander in 2433 m water depth at the LTER (Long-Term Ecological Research) observation HAUSGARTEN in eastern parts of the Fram Strait were sampled on 28th July 2015 using push-corer (PC) handled by the Remotely Operated Vehicle (ROV) QUEST 4000 (MARUM Center for Marine Environmental Sciences, Germany) during Dive 369 from board RV Polarstern. The block-shaped steel bottom-weights (30 x 30 x 6 cm) were sitting about half of the height sunken into the seafloor and thus, almost not affecting near-bottom currents. During sampling in 2015, the plates were largely corroded. Surface sediments around the plates had an orange-red color with a gradient of decreasing color intensity with increasing distance from the source, i.e., the bottom weight. A total of eight push-corer samples (PC1-8) were taken at approx. regular distances (on average every 18 cm) along a short transect (about 1.5 m) crossing the iron gradient. Push-corers PC1-4 retrieved sediment from heavily impacted sediments, while samples taken from push-corers PC5-8 were visually indistinguishable from background sediments in the wider area. After recovery of the ROV, sediment cores (8 cm in diameter, and 20-25 cm in height) were sub-sampled using plastic syringes with cut-off anterior ends for meiofauna and nematode communities as well as for environmental parameters. The position specified in the data sets (longitude / latitude) refers to the position of the ROV
Master track of POLARSTERN cruise PS126 in 1 sec resolution (zipped, 16 MB)
No full textRaw data acquired by position sensors on board RV Polarstern during expedition PS126 was processed to receive a validated master track which can be used as reference of further expedition data. During PS126 two Trimble Marine SPS461 GPS receivers and the iXBlue HYDRINS hydrographic survey inertial navigation system were used as navigation sensors. Data were downloaded from DAVIS SHIP data base (https://dship.awi.de) with a resolution of 1 sec. Processing and evaluation of the data is outlined in the data processing report found at EPIC repository https://hdl.handle.net/10013/epic.961ba6cf-9777-4203-af50-739f2acb380c. Processed data are provided as a master track with 1 sec resolution derived from the position sensors' data selected by priority and a generalized track with a reduced set of the most significant positions of the master track
Meiofauna abundance and biomass of sediment core GeoB1009-3
No full textMeiofauna abundance and biomass of sediment core GeoB1009-
- …
