GOBEX-III: Fahrtbericht / Cruise Report FS POSEIDON [POS215/2] Gotland Becken, Rostock - Kiel, 04.03. - 13.03.1996

Cruise GOBEX-III was the second expedition mounted by the IOW Marine Geology Group under Project GOBEX to investigate the geochemical and sedimentological environment in the Gotland Basin of the Central Baltic Sea. The cruise concentrated on improving the coverage with shallow seismic profiles (GEOCHIRP sonar), shallow sediment cores (Multicorer) and long gravity and Kasten cores of various depths in the Gotland Deep and adjacent basins. Using acoustic methods, we mapped the local accumulations of mud (Schlick) in basin-normal and along-strike profiles. The accumulations of mud and underlying lacustrine clays were sampled by shallow multi-coring and gravity coring (to 12 m, maximum or 10.5 m recovery). Cores were subsampled onboard ship for porewater, sedimentolngical, and magnetic analyses in shorebased laboratories. A first exploratory survey of sediments was carried out in the Gdansk Basin by seismic soLmdings, surface sediment sampling, and gravity coring. Two gravity cores were taken in the Arkona Basin

Fahrtbericht der Fahrt POSEIDON-199 [POS199] / Report of Cruise POSEIDON-199, Kiel - Kiel, 1.2.1993-6.2.1993

Cruise POS-199 was a first expedition under Project ODER to investigate the geological and sedimentological situation in an area east of the island of Riigen, where the submarine valley of the river Oder discharges into the southern Arkona-Basin. Using acoustic methods (3.5 kHz, Boomer, and Sidescan Sonar) in a closely-spaced grid of survey lines (2 sm apart in E-W trending profiles), we located accumulations of mud (Schlick) in an area characterized generally by sand deposition and -redeposition. Mud deposition is restricted to the deepest parts of the pre-transgressional river valley and to water depths below 20 mbsl. These accumulations of mud were sampled by box coring and gravity coring (where successful) and subsampled onboard ship for investigation of physical properties and subsequent analyses in shorebased laboratories. Future analyses will include sedimentological, radiochemical, micropaleontological and geochemical analyses to establish the dispersal, sedimentation and transformation of natural and manmade substances in the Oder depositional system

Biology and biogeochemistry of the eastern mediterranean sea : research vessel Meteor, cruise No. M71 ; 11. Dez. 2006 - 04. Feb. 2007

Die METEOR-Fahrt 71 umfasst 3 biologisch und biogeochemisch orientierte Fahrtabschnitte mit insgesamt 50 Schiffstagen im östlichen Mittelmeer und hat folgende Ziele: Der Abschnitt METEOR 71-1 dient der physikalischen, biogeochemischen und biologischen Probengewinnung im Bereich der Anaximander Mountains. Es gibt nur einige wenige Seeberge im östlichen Mittelmeeres, die weitgehend isoliert vom übrigen Ozean sind und in einer Region liegen, die sich durch ein im Vergleich zum Weltozean sehr warmes Tiefenwasser von rund 14 °C auszeichnet. Hauptziel der Untersuchungen an einem Gipfel der Anaximander Mountains ist die Beantwortung der Frage, ob sich ein Seeberg-Ökosystem in einer oligotrophen Region mit warmen Tiefenwasser in Bezug auf seinen Einfluß auf das umgebende Strömungs- und Nährstoffregime, die Produktivität und Verteilung der Nahrungsketten, sowie in Bezug auf die Größe der „Sphere of interference“, das heißt dem Einflußbereich des Seamounts auf den umgebenden Wasserkörper, ähnlich verhält wie entsprechende Erhebungen im Nordostatlantik. Die Expedition METEOR 71-2 beschäftigt sich mit der Biodiversität in der Tiefsee des östlichen Mittelmeeres und ihren Steuerungsfaktoren (Tiefe, Küstenabstand, Nahrungsverfügbarkeit). Zum einen geht es um eine möglichst vollständige Erfassung der Artenzusammensetzung in zwei Referenzregionen durch Vielfachbeprobung an der selben Stelle, zum anderen um die Unterschiede des Arteninventars und des Artenreichtums in Abhängigkeit von der Tiefe und vom Küstenabstand. Die Arbeitsgebiete von jeweils 17 sm x 5 sm sind das Ierapetra-Becken südlich Kreta. (> 4000m Tiefe) und ein Gebiet der gleichen Größe weiter südlich (2800 m Tiefe doppelter Abstand zur Küste).Die Untersuchungen berücksichtigen alle Grössenklassen des Benthos (Mega-, Macro-, Meiound Nanofauna), um Gemeinsamkeiten und Unterschiede in der Abhängigkeit der Biodiversität von Ökofaktoren zu erkennen. Damit sollen die Struktur und die Funktion der Lebensgemeinschaften am äußerst oligotrophen Tiefseeboden des levantinischen Beckens besser und detaillierter verstanden werden. Arbeiten der Expedition METEOR 71-3 zielen auf die Klärung der Frage, ob im heutigen Mittelmeer Phosphatverlust und unvollständige Nitratnutzung, oder Stickstoff-Fixierung im ultraoligotrophen östlichen Mittelmeer für isotopisch abgereicherte d15N Signaturen von Sedimenten und Schwebstoffen verantwortlich sind. Ein Nebenziel ist die Gewinnung zusätzlicher Oberflächensedimente, um die Datenbasis für Eichungen des UK´37-Index und Abschätzung der Nährstoffakkumulationsraten in Sedimenten im Mittelmeers zu verbessern. Dazu werden auf Schnitten durch das östliche Mittelmeer Nährstoffprofile beprobt, Proben für Messungen der 15N/14N-Verhältnisse in Nitrat, gelöstem organischem Stickstoff, in Sinkstoffen und Oberflächensedimenten gewonnen, Untersuchungen des Phytoplanktons sowie Messungen von N2-Fixierungsraten durchgeführt. Weiter werden molekulare Techniken eingesetzt, um das Vorhandensein und die Transkription der nifH-Gene für das Nitrogenase-Enzym diazotropher Organismen zu überprüfen. Die Methoden zielen auf das nifHGen und seine Transkripte und geben Aufschluss über das Potential für Stickstofffixierung. Die Ergebnisse werden zeigen, ob das Gen aktiv in der Plankton-Gemeinschaft transkribiert wird. Ferne wird mit der DNA Sequenzanalyse neben der Anwesenheit auch die Diversität der diazotrophen Organismen etabliert. Schließlich wird im Verlauf der Fahrt an einer Station im Rhodos-Becken eine Sedimentfalle ausgebracht.Meteor expedition 71 has a total of 50 ship days on 3 individual legs. Research is directed towards investigations into deep-sea biology and biogeochemistry of the eastern Mediterra-nean Sea. Goals of the individual legs are: Leg Meteor M71/1 focuses on physical, biogeochemical and biological sampling at the Anaximander Mountains. There are only very few seamount-like structures in the eastern Mediterranean. They are fairly isolated from the world ocean and are located in a region with exceptionally high temperatures of 14 °C in the deep-water layers. The primary goal of the studies at one peak of the Anaximander Mountains is to assess if a seamount ecosystem in an oligotrophic region with a warm deep-water layer is comparable with similar topographic feature in the NEAtlantic, which have been studied within the EU funded project OASIS. In particular, we plan to study if these systems in different oceanographic regimes have similar impacts on the current field and on the particle flux, and if they are similar with regard to their productivity, the distribution of their food webs and their sphere of interference, i.e. the extention of the space which is affected by seamount processes. Leg METEOR 71-2 studies the biodiversity of the deep sea in the eastern Mediterranean Sea and controlling factors (water depth, distance to land, nutrient availability). One goal is to assess the species composition in two reference fields through repeated sampling of the sea floor. The second goal is to map differences in assemblages and species richness in relation to water depth and distance from land. The two reference fields of 17nm x 5 nm are located in the Ierapetra-Deep south of Crete (water depth >4000 m) and an area of the same size located furhter south (water depth 2800m double distance to the coast)The on-board investigations extend to all size classes of benthic organisms (mega-, macro-, meio-, and nanofauna) in order to search for similarities and differences that determine biodiversity and its relationship with ecosystem boundary conditions. This work will result in an improved and detailed understanding of ecosystem structure and functioning in an ultraoligotrophic sea floor region of the Eastern Mediterranean. Work on M71-3 aims to answer the question whether phosphate loss and incomplete utilisation of nitrate on the one hand, or dinitrogen fixation on the other hand are responsible for unusual nutrient ratios in the water column of the eastern Mediterranean Sea. We also seek to find the reason for unusually depleted 15N/14N ratios in dissolved nitrate, suspended matter and surface sediments of that oligotrophic ocean basin. During a total of 18 days of ship time on r/v METEOR, Leg 3 OF M71 will perfom water column and surface sediment work in the eastern Mediterranean Sea (Heraklion-Istanbul). Stations will be aligned on one E-W and two N-S transects and will sample all major basins and water masses. We will analyse water samples for nutrients, and will determine the stable nitrogen isotope composition of dissolved nitrate, suspended matter, and surface sediments. In addition, phytoplankton samples will be taken and experiments will be carried out to determine N2 fixation rates, genetic expressions of nitrogen fixation, and the composition of microbial and algal assemblages. One mooring of sediment traps (Rhodes Gyre) will be deployed and recovered after one year to monitor changes in particle flux and its isotopic signature over a seasonal cycle. An ancillary goal is to sample surface sediments for determinations of diagenetic effects on the 15N/14N signal in combination with analyses of amino acid degradation and calibration of the alkenone unsaturation index UK’ 37

Nitrogen removal in coastal sediments of the German Wadden Sea

Although sediments of the German Wadden Sea are suspected to eliminate a considerable share of nitrate delivered to the SE North Sea, their denitrification rates have not been systematically assessed. We determined N2 production rates over seasonal cycles (February 2009-April 2010) at two locations with two sediments types each, the first site (Meldorf Bight) receiving nitrate during all seasons from the Elbe river plume, and a second site on the island of Sylt, where nitrate is depleted during summer months. In sediments from the Sylt site, N2 production ranged from 15 to 32μmol N2m−2h−1 in the fine sand station and from 7 to 13μmol N2m−2h−1 in the coarse sand station; N2 production was not detected when nitrate was depleted in May and July of 2009. N2 production in the Meldorf Bight sediments were consistently detected at higher rates (58-130μmolN2m−2h−1 in the very fine sand station and between 14 and 30μmol N2m−2h−1 in the medium sand station). Analysis of ancillary parameters suggests that major factors controlling N2 production in coastal sediments of the German Wadden Sea are the nitrate concentrations in the overlying water, the ambient temperature, and the organic matter content of the sediment. Extrapolating our spot measurements to the zone of nitrate availability and sediment types, we estimate an annual nitrogen removal rate around 16 kt Nyear−1 for the entire northern sector of the German Wadden Sea area. This corresponds to 14% of the annual Elbe river nitrogen loa

SEA SURFACE TEMPERATURES RECONSTRUCTION OF THE LAST 16,000 YEARS IN THE EASTERN MEDITERRANEAN SEA

A detailed study has been performed on two eastern Mediterranean box cores (BC02 and BC06) and on a southern Adriatic piston core (AD91-17) on the alkenone unsaturation ratio, a molecular proxy for past sea surface temperatures. The aim was to identify climatic events of the last 16 Ky, with particular attention on the conditions during formation of sapropel S1. All three temperature curves lack evidence for cooling in the Younger Dryas stadial and warming in the Boelling/Alleroed interstadial events. Just prior to the sapropel S1 base, SST cooled and increased by about 5°C during the sapropel deposition interval. Within sapropel S1, SST show a marked warming followed by a clear cooling. In the topmost intervals of the cores SST are mostly constant, but a warming event is always observed. This warming phase may correspond to the Medieval climatic Optimum (in the AD91-17 core) and to the Roman Optimum (in the box cores)

The olfactory organs of deep-sea fishes : their morphology and possible role in mate location

The last 5500 years of climate change and environmental response in the northern Benguela Coastal Upwelling are reconstructed by means of three sediment cores from the inner shelf off central Namibia. The study is based on nutrient (δ15N, δ13C) and productivity proxies (accumulation rates of total organic carbon; ARTOC). Reconstructed sea surface temperatures (alkenone-derived SST) and temperatures at subsurface depths (Tδ18O; based on tests of planktonic foraminifers) reflect the physical boundary conditions. The selection of proxy indicators proved a valuable basis for robust palaeo-climatic reconstructions, with the resolution ranging from multi-decadal (NAM1) over centennial (core 178) to millennial scale (core 226620). The northern Benguela experienced pronounced and rapid perturbation during the middle and late Holocene, and apparently, not all are purely local in character. In fact, numerous correlations with records from the adjacent South African subcontinent and the northern hemisphere testify to global climatic teleconnections. The Holocene Hypsithermal, for instance, is just as evident as the Little Ice Age (LIA) and the Roman Warm Period. The marked SST-rise associated with the latter is substantiated by other marine and terrestrial data from the South African realm. The LIA (at least its early stages) manifests itself in intensified winds and upwelling, which accords with increased rainfall receipts above the continental interior. It appears that climate signals are transferred both via the atmosphere and ocean. The combined analysis of SST and Tδ18O proved a useful tool in order to differentiate between both pathways. SSTs are primarily controlled by the intensity of atmospheric circulation features, reflecting changes of upwelling-favourable winds. Tδ18O records the temperature of the source water and often correlates with global ocean conveyor speed due to varying inputs of warm Agulhas Water. It seems as though conveyor slowdown or acceleration not only affected the temperature of the source water but also its nutrient content. This relationship between source water quality and conveyor speed is already known from glacial times

Bilanzierung und Quantifizierung des Chlorbiphenyl-Eintrages in das Oderhaff

Under the EC sponsored research project ODER (Oder Discharge-Environmental Response) first investigations have been carried out to estimate the chlorinated biphenyls (CB) input into Oderhaff via the Oder river. For this purpose, vertical profiles of CB content and composition were analysed on samples of three sediment cores. In two water samples, the content of suspended particulate material as weil as the particulate CB content and congener-specific composition were measured. In the Oderhaff the CB concentrations of particulate material were between 700 to 800 pg/dm3. Significant differences in the composition of the components were not observed. In sediments, CB contents were as high as 17 to 24 ngig dry weight in near surface sediment layers. They decreased with increasing sediment depth and were below detection limits at 15 to 21 cm depth. Based on the size of the 49 accumulation area and related hydrographic conditions, we estimated an input of 95 kg into the Oderhaff for the last 65 years since the onset of CB production. Applying the present prevailing conditions, we calculated an average transport of about 825 kg CB by the Oder river during this period. Comparing these two estimates, we observed that at least 15 % of the CB transported by the Oder river was deposited in the Oderhaff. The remaining 85 % (-730 kg), have been further transported into the South Pomeranian Bight and Southern Baltic Sea

Research vessel Meteor, cruise no. 48 : 6 July - 3 November 2000

Die fünf Abschnitte der Meteor-Reise 48 führen in die Zone der Ostrandzirkulation des Südost-Atlantiks und verknüpfen ozeanografische, biologische, geologische und chemische Arbeiten im Bereich des Auftriebsgebietes vor der südwest-afrikanischen Küste sowie im Pelagial des Angolabeckens und des Kapbeckens. Die Arbeiten konzentrieren sich auf · die Biodiversität von Benthosgemeinschaften in Tiefseebecken, · biogeochemische Stoffkreisläufe und kurzskalige holozäne Klimavariationen im Auftriebsgebiet vor Namibia, · die Dynamik des Angola Domes und des Benguelastromes und die Entstehung des Südäquatorialen Gegenstroms im Atlantik, · die Verteilungen von Spurenelementen und natürlichen Radionukliden im Auftriebsgebiet vor Namibia, · den Einfluss mesoskaliger physikalischer Strukturen und Prozesse auf die Produktion des Zooplanktons im nördlichen Benguela-Auftriebssystem.The five legs of Meteor cruise 48 lead into the eastern boundary circulation of the south-eastern Atlantic, combining oceanographical, biological, geological, and chemical work in the upwelling area off the coast of Namibia and the pelagic region of the Angola and the Cape basin. Studies focus on · biodiversity of the benthos community in deep sea basins, · biogeochemical cycles and short-scale holocene climate variations in the Namibia upwelling region, · dynamics of the Angola dome and the Benguela current, and the formation of the southequatorial contercurrent in the Atlantic, · distributions of (essential) trace elements and natural radionuclides in the Namibia upwelling region · the influence of mesoscale physical structures/processes on the production of zooplankton in the northern Benguela upwelling system

The impact of intertidal areas on the carbonate system of the southern North Sea

The coastal ocean is strongly affected by ocean acidification because of its shallow water depths, low volume, and the closeness to terrestrial dynamics. Earlier observations of dissolved inorganic carbon (DIC) and total alkalinity (TA) in the southern part of the North Sea, a northwest European shelf sea, revealed lower acidification effects than expected. It has been assumed that anaerobic degradation and subsequent TA release in the adjacent back-barrier tidal areas (Wadden Sea) in summertime is responsible for this phenomenon. In this study the exchange rates of TA and DIC between the Wadden Sea tidal basins and the North Sea and the consequences for the carbonate system in the German Bight are estimated using a 3D ecosystem model. The aim of this study is to differentiate the various sources contributing to observed high summer TA in the southern North Sea. Measured TA and DIC in the Wadden Sea are considered as model boundary conditions. This procedure acknowledges the dynamic behaviour of the Wadden Sea as an area of effective production and decomposition of organic material. According to the modelling results, 39 Gmol TA yr−1 were exported from the Wadden Sea into the North Sea, which is less than a previous estimate but within a comparable range. The interannual variabilities in TA and DIC, mainly driven by hydrodynamic conditions, were examined for the years 2001–2009. Dynamics in the carbonate system are found to be related to specific weather conditions. The results suggest that the Wadden Sea is an important driver for the carbonate system in the southern North Sea. On average 41 % of TA inventory changes in the German Bight were caused by riverine input, 37 % by net transport from adjacent North Sea sectors, 16 % by Wadden Sea export, and 6 % were caused by internal net production of TA. The dominant role of river input for the TA inventory disappears when focusing on TA concentration changes due to the corresponding freshwater fluxes diluting the marine TA concentrations. The ratio of exported TA versus DIC reflects the dominant underlying biogeochemical processes in the Wadden Sea. Whereas aerobic degradation of organic matter played a key role in the North Frisian Wadden Sea during all seasons of the year, anaerobic degradation of organic matter dominated in the East Frisian Wadden Sea. Despite the scarcity of high-resolution field data, it is shown that anaerobic degradation in the Wadden Sea is one of the main contributors of elevated summer TA values in the southern North Sea