ALBERT

Description: In the present work the impact of broken clouds on solar irradiance at the surface is studied. This study is based on the region of Kiel, becausc of realisation of land and seameasurements. To this end data from pyranometer and ceilometer, which are available at the Institut für Meereswisscnschaften, are used. On thc basis of these data (march 1997 until october 2003) statements about variation in solar irradiance by different cloud amount over land opposite to the reference of clear sky case at the lighthouse Kiel are made. Beside the decrease in irradiance, so-called shadowing effect, an extra amount of irradiance by broken cloudiness adds to the amount of direct irradiance. The extra amount of irrandiance is given by reflection of solar radiance at cloud sides. The english technical literature refers to the enhancemcnt as "broken cloud effect" (bce). The enhancement ranges from some W/m2 until 300 W/m2. This depends on the typ of cloud and the solar zenith angle. The bc rcsults from cumuli, which accumulate by convection at the time of land-sea-breeze-circulation. The frequency of occurrence of thc bc-events are significant coupled with the sea-breeze-circulation. The effect can be observed soonest in spring and in early and late summer, if and only if the formation of sea-breeze-circulation is most likely and as a consequence thereof the fine weather cumuli are developed. In June the broken cloud effect occurs very often owing to the small solar zenith angles of 30°, which arc typical for this month. A further dependance exists in cloud amount. The increase in radiance is maximal by a cloud over of 6/8. Consequently the bce cannot be oberserved neither at cloud1ess nor at completely covered sky. A concluding aspect for this work consists in modelling the bce with the model called GRIMALDI, which is advanced at the Institut für Meereswissenschaften. In this model a homogeneous plan-parallel cumulus cloud is implemented. For different solar zenith angles and cloud covers a relation to the pre-achieved results will be carried out. There is a distinctive bce in the model, too. Differences between the modelled and the calculated radiant fluxcs can be explained by the high simplified cumulus clouds.

Description: The present study was conducted as part of the German contribution to the GLOBEC (Global Ocean Ecosystems Dynamics) program in June 2003. lt was intended to investigate possible effects of frontal systems in the German Bight of the North Sea on the growth characteristics of sprat ( Sprattus sprattus) larvae by means of otolith microstructure examination. However, it turned out that the majority of sampled larvae were not sprat but pilchard (Sardina pilchardus). This unusual occurrence of pilchard spawning coincided with unusually high temperatures in summer 2003. This might be regarded as an indicator for a shift of southern species to areas further north due to climate variability. The species distribution in the two frontal systems investigated, a tidal mixing front and a river plume front, seemed to be influenced by the hydrographic properties. Pilchard dominated in water bodies with characteristics of their usual spawning grounds further south, i.e. waters with higher temperatures and salinities. Sprat, on the other hand, which is a native spawner in the area and known to tolerate very low salinities, was predominantly found in colder and less saline water bodies. The biotic and abiotic properties of waters in and close to the tidal mixing front also seemed to generally provide favourable conditions for growth. Larvae sampled at different stations on a transect across the tidal mixing front also showed differences in growth rates. Highest growth rates were found in larvae caught at a stratified station further offshore. This was probably due to the higher chlorophyll-a content that was observed 6 days prior to catch at this station, which was suspected to also indicate higher abundances of potential larval food. However, a second observation on the day of catch indicated that chlorophyll-a and, thus, suspected food availability had reversed after a storm event that occurred between the two observations. Some evidence was found from the otolith microstructure examination that this shift in food availability is reflected in larval growth performance. Regarded in conjunction with high larval abundance close to the coast, this led to the conclusion that the fronts in the German Bight might act as retention areas for larvae providing conditions that have a positive effect on larval growth, survival and subsequent recruitment. Additionally, it was found that pilchard larvae expressed better growth rates than sprat larvae. This could mean that pilchard larvae are potential rivals to the native sprat, competing for resources like food and habitat, and an effect of the pilchard spawning in the German Bight on the North Sea ecosystem can not be ruled out.

Description: The focus of the present study was to investigate the soft bottom community (including in- and epifauna) at the coastal slope (5 m to 30 m) in Kongsfjorden, and to estimate its importance as food source for demersal fish. For these purposes the macrozoobenthos was sampled at six sampling locations. In total 30 samples were taken (6 x 5 replicates) by means of a steel frame of 192 cm2 area size. A suction pump ("airlift") collected the soft bottom fauna within the designated area. Polychaets (84 %), molluscs (10 %) and crustaceans (3 %) dominated the soft bottom community. In total, 63 species were found, including 30 species which have not been recorded in Kongsfjorden earlier. Seven species have not yet been recorded for the entire archipelago of Svalbard (according to Gulliksen et al. 1999). The average abundance was 6293 individuals m-2, the average biomass was 14 g ash free dry mass (afDM) m-2. Three community types could be identified by means of clusteranalysis and multidimensional scaling: The „shallow water" - community at 5 m (28 species; 2260 individuals m-2; 3.5 g m-2 afDM), the „mid-water"- community between 10 m and 20 m (51 species; 7184 individuals m-2; 20.7 g m-2 afDM) and the deepwater"- community in the range of 25 m and 30 m (44 species; 6982 individuals m-2; 10.6 g m-2 afDM). The species found were then categorized with respect to their feeding ecology and were classified to their zoogeography. Five species were omnivorous, 23 carnivorous, 25 detritivorous and 18 suspesion feeders. Most of the species (34) were arctic-boreal followed by cosmopolitan species (20); only five species were true arctic. Furthermore ecological indices were calculated: the Margalef Index (1.45°-02.23), Shannon-Wiener diversity (1.85°-02.19) and evenness (0.67°- 00.82). Six dominant species (〉 10 %) were identified (Crassicorophium crassicorne, Chaetozone setosa, Dipolydora quadrilobata, Euchone analis, Scoloplos armiger and Spio armata) and three were determined as indicator species (Oipolydora quadrilobata, Euchone analis and Scoloplos armiger). Nine species of demersal fish were found in shallow areas (5 m to 30 m) of Kongsfjorden: Anarhichas lupus, Anisarchus medius, Eumicrotremus derjugini, Gadus morhua, Gymnacanthus tricuspis, Leptoclinus maculatus, Liparis liparis, Lumpenus lampretaeformis and Myoxocephalus scorpius. According to the literature these fish species were feeding on the bottom community, in particular on taxa witch found at this study Priapulus caudatus, Scoloplos armiger, Anonyx sarsi, Crassicorophium sp., Ischyrocerus sp., Monoculodes tesselatus, Onisimus edwardsi, Sclerocrangon boreas and Ophiura sarsi. Polychaets (up to 87 %), amphipods (up to 56 %), molluscs (up to 50 %) and echinoderms (up to 48 %) dominated the spectrum of food source.

Description: Difficulties in characterisation of sprat populations in the Baltic Sea have lead to the determination of only one management unit for the ICES subdivisions 22-32. To prevent mistakes in management which could result in overfishing and exploitation, stock differentiation for the Baltic sprat is demanded from several sides. Genetic tools are considered as helpful to meet these demands and it is hoped to lead that they will provide new information about the number and distiibution of existing stocks. The use of microsatellite-loci is an approach for genetic stock identification. Microsatellites are highly informative genetic markers useful for population genetic studies, lineage mapping and parentage detection. Usually, microsatellites have to be identified anew for every species examined because the flanking regions of the repeat sequences differ between most taxa. An approach for isolation of tandem repeated sequences in the genomic DNA of the sprat, Sprattus sprattus is desciibed here. Genomic DNA was fragmented, attached linkers and prepared for ligation into a plasmid vector. Specific repeat elements were captured using biotinylated oligonucleotide probes in solution and subsequent attachment to streptavidin-coated magnetic beads. Captured fragments were amplified by PCR and cloned into the vector. The product of this expeiiment was a library enriched for defined microsatellite-sequences. Clones from this library were selected and their inserts were sequenced due to the detection of repeat motives. The results presented here show that this approach is effective to isolate dinucleotide- repeat sequences. For the enrichment two tetranucleotides, AGAT(7) and TATC(7) and one dinucleotide, GT(15) were used. GT(n) repeats were found in all of the thirty dinucleotideenriched DNA samples, sequenced. Contraiily, in none of the tetranucleotide-enriched samples repeat sequences could be identified. This study shows that in general the isolation of repeat sequences of genomic sprat DNA is possible. The development of microsatellite markers suitable for stock identification of the sprat in the Baltic Sea was discussed here.

Description: Die vorliegende Arbeit befaßt sich mit der Nahrungsökologie von überwinternden Eis- und Trauerenten. ( Clangula hyemalis und Melanitta nigra). Die auf den Mageninhalt untersuchten Vögel stamnen aus Beifängen der Stellnetzfischerei vor der Insel Usedom. Darüber hinaus wurden die Ergebnisse mit verfügbaren vorhandenen Nahrungsdaten der genannten Entenarten verglichen. Die Tatsache, daß solche nur in relativ wenigen Veröffentlichungen zu finden sind, war zugleich Ansporn für diese Arbeit, sich mit der Beziehung zwischen Meeresenten und Benthos näher zu befassen. Die untersuchten Trauerenten hatten vornehmlich Baltische Plattmuscheln (Macoma balthoica) gefressen, während bei den Eisenten die Sandklaffmuschel (Mya arenaria) an erster Stelle stand. Im Vergleich mit anderen Daten ergab sich, daß die Nahrungszusammensetzung regional zwar verschieden ist das unterschiedliche Angebot an Nahrung war dabei aber nicht unbedingt der einzige bestimmende Faktor. So wurden z.B. Miesmuscheln (Mytilus edulis) in der Hohwachter Bucht kaum gefressen, obwohl sie dort sehr häufig siITd (Kirchhoff, 1979). Bei den Eisenten wurden auch einige andere Invertebraten sowie vereinzelt Fisch oder Laich gefunden, während die Trauerenten ausschließlich Muscheln gefressen hatten. Bei der Arbeit auftauchende Fragen sollen Anregung sein, die Thematik weiter im Auge zu behalten, um durch eventuelle künftige Forschungen ein umfassenderes Bild über Meeresenten,deren Verhalten und Ernährung zu bekommen.

Description: Die vorliegende Arbeit entstand m Zusammenarbeit zwischen dem Leibniz-Institut für Meereswissenschaften an der Universität Kiel und der Bundesforschungsanstalt für Fischerei in Hamburg. Ziel der Arbeit war die Beschreibung der räumlichen Verteilungsmuster von Heringen ( Clupea harengus L.) und Sprotten (Sprattus sprattus L.) in der südlichen Nordsee in Relation zu den hydrographischen Bedingungen. Dabei sollten für beide Arten nach Möglichkeit bevorzugte Temperatur- und Salzgehaltsbereiche angegeben werden. Zusätzlich sollten Sehwarmparameter (Länge, Höhe, Umfang und Fläche der Schwärme) für Heringe und Sprotten ermittelt werden. Diese Werte , sollten die Grundlage dafür schaffen, in hydroakustisch untersuchten Gebieten der Nordsee Rückschlüsse auf die ArtenZusammensetzung zu ziehen. Die Auswertungen basierten auf hydroakustischen Daten, die jeweils im Juni und Juli der Jahre 2002 und 2003 mit dem Forschungsschiff „Walter Herwig III" aufgezeichnet wurden. Während der beiden Seereisen wurden neben den hydroakustischen Aufnahmen Fischereistationen und CTD-Stationen durchgeführt. In beiden Jahren konnten identische Verteilungsmuster der beiden Arten festgestellt werden. Die Heringe waren fast ausschließlich in den nördlichen Teilen des Untersuchungsgebietes lokalisiert, während sich die Sprotten vornehmlich in den südlichen Gebieten aufbielten. Es konnten Zusammenhänge der beschriebenen Verteilungsmuster mit den Temperaturen des Tiefenwassers nachgewiesen werden. Die Heringe bevorzugten warme Temperaturen, während die Sprotten kältere Temperaturen präferierten. Es konnten außerdem Zusammenhänge zwischen den Verteilungsmustern von Heringen und Sprotten und dem Auftreten von tidal-mixing-Fronten nachgewiesen werden. Die Heringe hielten sich fast ausschließlich im vertikal geschichteten Bereich auf, während die Sprotten entweder im durchmischten Bereich oder in den Bereichen, in denen die größten horizontalen Schichtungsgradienten beobachtet werden konnten, lokalisiert waren. Weiterhin wurde festgestellt, dass die Heringe in beiden Jahren echointensivere Schwärme als die Sprotten bildeten. Die Unterschiede der ermittelten Sehwarmparameter von Heringen und Sprotten fielen gering aus. Es wurden von diversen Autoren Untersuchungen zu möglichen Präferenzen der Arten Hering und Sprott für hydrographische Bedingungen durchgeführt. Die ermittelten. Temperaturpräferenzen und auch die Zusammenhänge der Verteilungsmuster der beiden Arten mit dem Auftreten von Fronten deckten sich gut mit den Ergebnissen anderer Autoren.

Description: Populationdata help understand the distribution and abundance of animals. They are especially useful for decisions involving protected areas or the assessment of habitat importance. Methods for estimates of populations are numerous e.g. capture-recapture, marked animals with fluorescent pigments or photoidentification. Aerial surveys are used for large animals in a standardized approach (Tasker et al. 1984) and marine animals can be detected by the line transect method (land based surveys, shipboard or aeroplane counts). Line transect surveys involve travel along a predetermined course, counting all animals sighted within this transect. The band width in general takes up to 300 meters and extends to both sides of the ship or aeroplane. It can be difficult, though, to record these animals in a way that represents the population because seals spend most of their time submerged in the water and seabirds have continually changing spatial distributions. Many exogenous factors can influence the visibility; the distance at which animals can be seen at sea, the weather conditions or sea state and the varying capability of the different observers. The aim of this work was to examine the extent to which physical factors influence the probability of seals being seen. Reflection, contrast between the water and the object as well as the carmouflage of seals may all influence the visibility of seals under natural conditions. In addition, variables such as distance to observer, weather conditions and sea state were included. To examine this, digital photographs were taken of a seal model placed at sea to so as to simulate the line transect method. Gull models were also used close to the seal to examine the effect that this conspicuous colours might have on seal perception. A selection of the digital pictures was shown to 120 test persons who had to decide within two seconds if they could recognize a seal in the picture or not. The restricted time was chosen in an attempt to imitate line transect counts. The results of this work is the analysis of answers given by the test persons. The analysis showed that significantly less animals are detected with increasing sea state and distance or decreasing cloud coverage. The visibility of seals appears to depend critically on optical conditions such as the reflection of light, contrast or light intensity. Test persons recognized the seal more often when the picture was taken in mid afternoon, and more often when the model was to the South or North of the position of the photographer. Men spotted the seal more often than women. This study shows what kind of factors could bias the sighting conditions of seals. In order to influence visibility in a positive way, many constraints have to nteract in an optimal way. The results of this work could be integrated in population counts.

Description: Biodiversität ist ein vielschichtiges Konzept. Es ist wichtig, die Faktoren zu untersuchen, die Biodiversität erhöhen, verringern oder erhalten. Zwei der etabliertesten Modelle, die die trotz der aktuellen globalen Krise eines rasanten Artenverlusts tatsächlich sehr hohe Artenvielfalt zu erklären versuchen, sind die „Intermediate Disturbance Hypothesis“ (IDH) und die Produktivitäts-Diversitäts-Beziehung. Die IDH beschreibt die Diversität in Abhängigkeit von Störungen. Danach ist bei mittlerer Störungsintensität die höchste Diversität zu erwarten, da sowohl störungstolerante als auch konkurrenzstarke Arten koexistieren können. Die Abhängigkeit der Diversität von der Produktivität soll in ihrer Form vergleichbar sein. So ist auch bei mittlerer Produktivität mit maximaler Diversität zu rechnen, da die Minimalanforderungen (an die Versorgung mit Ressourcen) einer großen Zahl von Organismen erfüllt sind, das Angebot der Ressourcen aber noch nicht so hoch ist, dass Dominanz einiger überlegener Arten entsteht. Mit dem Ziel, die Konzepte zum Einfluss von Störungen und Produktivität auf die Artenvielfalt zu vereinen, hat Kondoh (2001) ein Modell entwickelt, das die vielfältigen Reaktionsmuster der Diversität auf Störungs- und Nährstoffregimes erklären könnte. Es sagt voraus, dass bei starken Störungen und niedriger Produktivität überlegene Kolonisierer und bei schwachen Störungen und hoher Produktivität überlegene Wettstreiter dominieren, in beiden Fällen die Artenvielfalt also niedrig bleibt. Höchste Artenzahlen sind nach diesem Modell bei ausgeglichenen Störungs- und Produktivitätsverhältnissen zu erwarten, da dann sowohl gute Kolonisierer als auch starke Wettstreiter überleben können. Um die Gültigkeit von Kondohs Modell zu prüfen, untersuchte ich in einem 2-faktoriellen ökologischen Experiment die wechselseitigen Effekte, die Störungen und Nährstofferhöhungen auf die Artenvielfalt einer felsigen Gezeitenküste bei zwei Standorten an Südafrikas Ostküste ausüben. Die von der IDH vorhergesagte unimodale Beziehung konnte in der vorliegenden Arbeit nicht empirisch bestätigt werden. Trotz starker Hintergrundvarianz zeigte die Nährstoffbehandlung in einer Reaktion von gemeinschaftsattributen Wirkung, wobei nur bei einem Standort die Diversität mit höherem Nährstoffangebot (entsprechend Kondohs Modell) anstieg. Die Ergebnisse zeigen weiter, dass die Reaktion der Artenvielfalt auf Störungen vom Nährstoffangebot abhängen kann. Der von Kondoh vorgeschlagene stetige interaktive Effekt von Störungen und Produktivität auf die Diversität wurde allerdings nicht bestätigt. Die viel diskutierten unimodalen Muster der Diversität entlang von Störungs- und Produktivitätsgradienten können weder das hier untersuchte noch die Mehrheit anderer untersuchter Systeme befriedigend beschreiben. Ich kann jedoch einige der ökologischen Mechanismen, auf denen die IDH und die Produktivitäts-Diversitäts-Beziehung beruhen, anhand meiner Ergebnisse nachvollziehen, weshalb ich weder diese beiden Konzepte noch Kondohs Modell widerlegen kann. Ich stimme den kürzlich postulierten Ansichten zu, dass die Entschlüsselung einer Vielzahl ökologischer Mechanismen vorangetrieben werden muss, um so durch die Entwirrung und Neuformulierung klassischer Konzepte allgemeingültige Muster aufdecken zu können.

Description: The Atlantic meridional overturning circulation (MOC) is thought to have strong impact on climate.Here results from a pilot project to monitor fluctuations of the MOC in the tropical North Atlantic are presented. The backbone of the experiment design is an end point measurement method. One main aspect of this study comprises a technical performance assessment of the different measurement components (density,bottom pressure,current velocities) of the moored array. For the interpretation of the observed mean and time variable volume transports, comparisons to independent observational data and numerical model output have been carried out and spectral analysis as well as basic theoretical aspects of fluid dynamics have been applied. Rossby waves represent a major source of noise, which may mask the MOC signal. A verification of the experiment design using model simulations attest the transport signal observed to be moderately representative for MOC and meridional heat transport fluctuations. An eastward extension of the array into the eastern trough might lead to a drastic increase in the signal-to-noise ratio.