ALBERT

Description: The bacterial communities associated with the brown algae Laminaria saccharina were investigated. For characterization in different geographical settings, seasons and also on the morphologically different parts of the alga, denaturing gradient gel electrophoresis (DGGE), cloning and phylogenetic analysis of l 6S rDNA sequences were used. Biologically active bacteria, isolated from L. saccharina in an earlier study, were sequenced and phylogenetically analyzed. In addition an infected laboratory culture of Laminaria digitata was studied by scanning electron microscopy and DGGE. Infected L. digitata samples yielded DGGE banding patters that indicated a stable bacterial community. Scanning electron microcopy revealed blister like structures on the infected phylloid, containing morphologically different microorganisms not occurring on healthy L. digitata phylloids. The 16S rDNA DGGE banding pattems of L. saccharina from natural habitats indicated a specific bacterial community associated with the young and healthy algal tissues. Seasonal, geographical and algal-part specific differences were observed. Cloning experiments identified 18 phylotypes ( 6 in the Alphaproteobacteria, 8 in the Gammaproteobacteria and 4 in the Bacteroidetes group) derived only from Baltic L. saccharina, not shared by water-derived samples. This indicated a specific association of bacteria to L. saccharina. Furthermore sequence analysis of the L. saccharina-derived antimicrobially active isolates identified strain LD8 l to be a novel member of the Alphaproteobacteria with less than 96% sequence similarity to its closest relatives, Koprimonas byunsanensis (DQ 167245) and Rhodospirillum rubrum (X87278). These findings lead to the assumption, that L. saccharina provides a abitat for specifically associated bacteria and a source for the detection of novel bacterial species with antimicrobial activities.

Description: Aim of this study was the investigation of the vertical dis-tribution of N2O and the factors influencing this distribu-tion. Dissolved and atmospheric N2O was measured in the North Atlantic Ocean and the Baltic Sea. These data, in com-bination with physical and chemical parameters, were used to determine sources and sinks of N2O. Possible production pathways were investigated using the relationship between N2O and relevant production parameters, and their relation to physical processes in the oceans. The hypothesis whether N2O concentrations increased by oceanic iron fertilization via enhanced substrate supply for microbial respiration, was tested during the European Iron Fertilization Experi-ment (EIFEX) in the subpolar South Atlantic. The vertical structure of bacterial communities in the subtropical North Atlantic was investigated, with the intention to find corre-lations between the community structure of bacteria and the distribution of N2O. In summary, this study presents a de-tailed picture of the distribution of N2O in the North At-lantic Ocean and the Baltic Sea and adds 80 profiles of the Atlantic and 26 profiles of the Baltic Sea to the database.

Description: Die vorliegende Arbeit untersucht, inwieweit die Photonenweglängenverteilung der durch Wolken transmittierten solaren Strahlung Informationen über die Wolkeneigenschaften enthält und sich damit zur Wolkenfernerkundung eignet. Hierzu wurden Photonenweglängen (PPL) mit dem rückwärts rechnenden Monte-Carlo-Strahlungstransportmodell MC-UNIK-BW für dreidimensional inhomogene Wolkenfelder aus hydrodynamischen Modellläufen des mesoskaligen Atmosphärenmodells GESIMA simuliert. Die stärkste Korrelation der mittleren PPL mit den 13 untersuchten Wolkeneigenschaften liegt für die optische Dicke der Wolken vor. Relativ unabhängig von dieser Beziehung zeigt sich die Verbindung der PPL zur internen Wolkeninhomogenität. Der Einfluss der Inhomogenität zeigte sich auch in dem Vergleich zwischen einer gemessenen und einer modellierten PPL. Des Weiteren stellt sich heraus, dass ein existierender Zusammenhang zwischen der PPL und den Wolkeneigenschaften für einen größeren horizontalen Bereich der Wolken Gültigkeit behält. Durch die Aufspaltung des Datensatzes an PPL-Simulationen in unterschiedliche Messsituationen ergaben sich neue Korrelationen mit zum Teil deutlichen Verbesserungen der Korrelationen im Vergleich zum gesamten Datensatz. Daneben wurde auch der Einfluss der Gasabsorption auf die resultierende PPL und die Änderung der PPL mit der Variation des Messortes in einem Wolkenfeld untersucht.

Description: Although cognisance of swim speed is fundamental to understanding the broad context of marine animal behaviour (impacting on dive duration, dive depth, foraging range, foraging success, breeding success and energy expenditure ), numerical determination of speed has proved problematic. Many different methods for assessment of swim speed are known to be problematic to some extent. This study investigates the potential of newly-developed tri-axial acceleration-measuring data-loggers for assessing the movement, and determining the swim speed, of selected marine vertebrates. Three different methods were used to calculate swim speed of a Harbour seal (Phoca vitulina) and Imperial cormorants (Phalacrocorax atriceps). Acceleration data recorded from a captive seal were used 1) to determine flipper stroke frequency and amplitude as a measure of swim speed and 2) to calculate velocity from acceleration using pure physics. In addition, 3) static acceleration due to body angle and the change of 〈live depth was used to calculate swim speed from free-ranging cormorants during descent and ascent phases of dives to the seabed. Although acceleration is clearly a useful tool to assess animal activity, it seems generally to be a poor indicator of speed. Dynamic acceleration accurately allowed determination of flipper stroke frequency and amplitude but the derivation of speed could only be used for horizontal swimming and even here was inappropriate during glide phases. U se of a pure physics approach and dynamic acceleration led to unrealistically high calculated speed values of up to 40 m/s, primarily due to cumulative errors, problems in separating static from dynamic acceleration and errors due to difficulties in determining the longitudinal axis measured by the accelerometer with respect to the longitudinal axis of the animal. The best results for speed were gained using simple trigonometry to calculate speed from static acceleration due to body angle and vertical change in depth. Thus, although measurement of triaxial acceleration can enhance the understanding of biological processes in free-living animals enormously, without easurement of other parameters, simple acceleration does not appear reliable for estimating the speed of marine animals.

Description: Wolken spielen im globalen Wasser- und Energiekreislauf eine bedeutende Rolle. Ständig sind rund 66% der Erde von Wolken bedeckt. Der Bedeckungsgrad variiert auf saisonalen, interannualen und interdekadischen Zeitskalen. In dieser Diplomarbeit soll neben der saisonalen Variabilität der Bedeckung auch die interannuale und interdekadische Variabilität des Bedeckungsgrades in einem gekoppelten Atmosphäre/Ozean Zirkulationsmodell ECHAM5/NEMO untersucht werden. Im weiteren werden Wechselwirkungen zwischen dem Bedeckungsgrad und anderen Klimavariablen (SST, Bodenluftdruck, Niederschlag) betrachtet. Im ersten Teil (Kapitel 5 und 6) der vorliegenden Arbeit wird zur Validierung der Modelldaten eine Vergleichsstudie mit globaler Wolkenbedeckung aus Satellitenbeobachtungen des International Satellite Cloud Climatology Project (ISCCP) durchgeführt. Die globale Verteilung der Gesamtbedeckung im Modell folgt entsprechend den Beobachtungsdaten der für die verschiedenen Klimazonen typischen Verteilung. Es zeigen sich jedoch lokale Differenzen. So ist die globale Gesamtbedeckung im Model global um 2,46% höher als beobachtet. Die Gesamtbedeckung in den Tropen, Subtropen und Teilen der mittleren Breiten wird vom Modell unterschätzt, in den subpolaren und polaren Breiten wird diese vom Modell überschätzt. Die saisonale Variabilität des Bedeckungsgrades wird vom Modell verstärkt wiedergegeben. Diese Unterschiede wurden auch in anderen Vergleichsstudien zwischen modellierter Bedeckung in GCMs und Satellitendaten gefunden. Der zweite Teil (Kapitel 7) dieser Diplomarbeit beschreibt Korrelationsanalysen zwischen dem Bedeckungsgrad und der SST sowie dem Bodenluftdruck. Anhand dieser Korrelationsanalysen werden Aussagen über gemeinsame Variabilitäten getroffen. Ziel ist es, Wechselwirkungen aufzuzeigen. Im Vergleich zwischen modellierter und beobachteter SST zeigen sich Abweichungen von bis zu 6 K. Ein Vergleich von Korrelationen zwischen Bedeckungsgrad und SST sowohl mit Modelldaten als auch mit Beobachtungsdaten zeigt jedoch, dass die Haupkorrelationsmuster vom Modell wiedergegeben werden. Jedoch können aufgrund der gröberen Auflösung im Modell kleinskalige Wechselwirkungen nicht im Detail wiedergegeben werden. Neben der SST nimmt der Bodenluftdruck starken Einfluss auf die Wolkenbedeckung. Muster hoher Korrelationen stimmen jedoch nur bedingt mit der klimatologischen Verteilung des Bodenluftdrucks und seinen Drucksystemen (Hochdruckgebiete, Tiefdruckgebiete) überein. Im dritten Teil (Kapitel 8) dieser Arbeit wird die Variabilität der Wolkenbedeckung auf verschiedenen vertikalen Leveln im Zusammenhang mit der Variabilität der Oberflächentemperatur und dem Bodenlufdruck untersucht. So kann gezeigt werden, dass Rahmenbedingungen am Boden wie Luftdruck und Temperatur mit Wolken in unterschiedlichen Höhen unterschiedlich stark wechselwirken. Im weiteren wird deutlich, dass sich der Anteil der Variabilität des Gesamtbedeckungsgrades aus Variabilitäten in unterschiedlichen Höhen und somit unterschiedlichen Wolkentypen zusammensetzt. Im letzten Teil (Kapitel 9 und 10) werden Rückkopplungen zwischen dominanten Mustern regionaler Klimavariabilität, ENSO und NAO, in Hinblick auf die Variabilität des Bedeckungsgrades untersucht.

Description: This diploma thesis analyses the negative change of the SST in the midlatitude on the north hemisphere in spring and summer, which has a connection to the atmospherical condition. The SST rise with incident solar radiation in spring and summer, so that the ocean mixed layer becomes thinner and warmer. And than the SST decreases about 0.5 Kelvin or more in 6 till 48 hours. This temperature subsidence can only explained with the mixing of the ocean mixed layer with colder water from below the mixed layer. When it comes from a atmospherical general conditions, this intermixture arise with the impaced of the wind.The wind stress transmits moment on the ocean and stimulate Ekman circulation and Langmuir circulation. The analyse base on data from a coupled run of the atmosphere circulation model ECHAM with the ocean model Mopy. The wind data and the data of the geopotentical high is used for the analyse. It is analysed in which atmospherical situation a negative change of the SST existed. The hypothesis is that a low in the midlatitude have a connection to the negative change of the SST. To show this, different statistical methods are used. The negative SST change exist in the area between the subtropical high and the lows in the midlatitude. A direct relationship between the SST change and the atmosphere is only found at the wind speed. The wind speed must increase clear compared with the wind speed of the time before. If the wind speed increases, the SST can decrease 0.5 Kelvin or more to the following time. When negative SST change exists, the mean of the wind speed is higher then the mean of the wind speed at all areas and time points. The comparison of the geopotentical height in 1000hPa level doesn't show a typical situation in which the negative SST change exist. The wind speed arises in different areas of a low and also in a high. On the other hand there is a relationship between negative SST change and geopotentical height in 500hPa level. The negative SST change exists often with eopotentical height in 500hPa level which is greater than the mean, that means in the subtropical air respectively is connected with a ridge. The polar front is connected with the ground over the dynamic lows in the midlatitude. The ridge belongs to ridge of high pressure and the warm section of a low. Between the ridge and the trough is the cold front at the ground. After the cold front the trough comes in the high level. The wind speed is weak in the high, so the ocean mixed layer can become thinner and warmer. When the low comes near, the wind speed becomes stronger and the ocean mixed layer is mixed with colder water. So the SST decreases and a negative SST change arises.

Description: This thesis shows different aspects of the distribution of zooplankton and the resulting influence on larval fish survival. The vertical distribution of the key calanoid copepod species in the Bornholm Basin (Baltic Sea), Pseudocalanus acuspes (Giesbrecht 1881), Temora longicornis (Müller 1792), Acartia bifilosa (Giesbrecht 1882), Acartia longiremis (Lilljeborg 1853) and the only cyclopoid copepod Oithona similis (Claus 1863), were investigated. Sampling was carried out with multiple opening/closing nets. The results showed distinct seasonal differences in the vertical distribution for all species. For P. acuspes an ontogenetic migration was detected, with the younger stage dwelling near the surface and the older stages moving successively deeper. The adults inhabited the water layers around the halocline. In November the vertical distribution disintegrated and all stages were distributed over the whole water column. However in this period the older stages (C4, C5) dominated the community. A diel vertical migration was observed for T. longicornis in the summer month (June 2001, July and August 2002). The migration was most distinc for the older stages, moving from 20 metre at night to almost 60 metre at day. No diel migration was observed in April and November. For Acartia species an extended daily migration was not observed, even though the weighted mean depth of Acartia longiremis in July shifted from 10 metre at night to 20 metre at day. Both Acartia species inhabited the water column above the thermocline in spring and summer. However, in November the distribution was broader for all stages in both species. All stages of O. similis inhabited the water layers around the halocline irrespective to the season, showing no vertical migration. The distribution of reproducing female P. acuspes was investigated with the Video Plankton Recorder, an in situ imaging device. The distribution was closely related to high salinity although low oxygen values were avoided. Based on images of female P. acuspes carrying egg sacs the number of eggs per clutch was calculated and using the temperature dependent development time an in situ egg production rate was estimated. Albeit the production was the same between years, the naupli to female ratio was higher in 2003 leading to the conclusion that the naupli mortality might have been reduced. A simple individual based model of P. acuspes connected to a circulation model of the Baltic Sea was used to reveal possible influence of drift to biomass changes. The results showed that in contrast to the 1980’s during the 1990’s the prevailing barotrophic circulation forced the majority of P. acuspes out of the Bornholm Basin into easterly Basins and shallow coastal regions. However, the transport of organisms produced in the eastern Basins (Gotland Basin and Gdansk Deep) back to the Bornholm Basin was limited. Lower salinity and higher temperature in the near shore water might influence the survival and reproduction. The same circulation model was used to investigate the drift of larval cod and possible consequences on the overlap with food organisms. Again, a shift in the baroclinic circulation between the 1980’s to the 1990’s led to an increased dispersion of larvae in the latter period. It was shown that this decreased the overlap with larval prey and thus decreased the survival probability of larval cod. Furthermore, the influence of variability in prey abundance and diversity on the results of an individual based model on larval cod growth and survival was investigated. It was shown, that the use of idealized mean prey fields led to an overestimation of larval survival. Using field data derived from net sampling the survival was partly reduced to 50%. Another investigated factor was the size of prey organisms. Again, the use of mean value led to an overestimation of survival. Using measurements from samples reduced the survival up to 75%.

Description: An advection-diffusion model coupled to a simple dynamical ocean model is used to illustrate the formation and ventilation of an oxygen minimum zone. The advection-diffusion model carries a tracer mimicking oxygen, and the dynamical model is a non-linear 1 ½ layer reduced-gravity model. The latter is forced by an annually oscillating mass flux confined to the near-equatorial band that, in turn, leads to the generation of mesoscale eddies and latitudinally alternating zonal jets at higher latitudes. The model uses North Atlantic geometry and develops a tracer minimum zone remarkably similar in location to the observed oxygen minimum zone in the Eastern Tropical North Atlantic (ETNA). This is despite the absence of wind forcing and the shadow zone predicted by the ventilated thermocline theory. Although the model is forced only at the annual period, the model nevertheless exhibits decadal and multidecadal variability in its spun-up state. The associated trends are comparable to observed trends in oxygen within the ETNA oxygen minimum zone. Notable exceptions are the multi-decadal decrease in oxygen in the lower oxygen minimum zone, and the sharp decrease in oxygen in the upper oxygen minimum zone between 2006 and 2013.

Description: Despite impressive results achieved by many on‐land visual mapping algorithms in the recent decades, transferring these methods from land to the deep sea remains a challenge due to harsh environmental conditions. Images captured by autonomous underwater vehicles, equipped with high‐resolution cameras and artificial illumination systems, often suffer from heterogeneous illumination and quality degradation caused by attenuation and scattering, on top of refraction of light rays. These challenges often result in the failure of on‐land Simultaneous Localization and Mapping (SLAM) approaches when applied underwater or cause Structure‐from‐Motion (SfM) approaches to exhibit drifting or omit challenging images. Consequently, this leads to gaps, jumps, or weakly reconstructed areas. In this work, we present a navigation‐aided hierarchical reconstruction approach to facilitate the automated robotic three‐dimensional reconstruction of hectares of seafloor. Our hierarchical approach combines the advantages of SLAM and global SfM that are much more efficient than incremental SfM, while ensuring the completeness and consistency of the global map. This is achieved through identifying and revisiting problematic or weakly reconstructed areas, avoiding to omit images and making better use of limited dive time. The proposed system has been extensively tested and evaluated during several research cruises, demonstrating its robustness and practicality in real‐world conditions.

Description: Aufgrund der globalen Klimaveränderungen werden für das Oberflächenwasser der Ostsee steigende Temperaturen sowie ein sinkender Salzgehalt erwartet. In dieser Arbeit wurde der Einfluss solcher Änderungen auf das Wachstum und die Schalenstabilität der Miesmuscheln (Mytilus edulis) untersucht. Eine erhöhte Temperatur führt zu höheren Wachstumsraten, während reduzierte Salinität sinkende Wachstumsraten und verringerte Schalenstabilität zur Folge hat. Dies ist insbesondere im Hinblick auf die Räuber-Beute-Interaktionen der Miesmuscheln von Bedeutung, da die Konsumption vieler Räuber gerade von Größe und Resistenz der Schalen abhängig ist. Aufgrund der zentralen Stellung von M. edulis in der Ostsee werden Verschiebungen in der Abundanz von Miesmuscheln auch für andere Organismen der baltischen Benthos-Gemeinschaften weitreichende Folgen haben.