ALBERT

Description: Predation pressure was examined for the epibenthic fauna of a intertidal seagrass bed of the Sylt-Rømø bight. Starting from the question for the dominant epibenthic prey and the intensity of predation pressure in seagrass habitats, we investigated a seegrasbed in the Sylt- Rømø bight. in sommer 2003. A predator enclosure experiment has been carried out in artificial tide pools of similar size, and a bait experiment were carried out in the surrounding seagrass bed. The most frequent epibenthic organisms within the intertidal seagrass beds consist of four dominant species: The brown shirmp (Crangon crangon, Linnaeus), the sand goby (Pomatoschitus microps, Krøyer), the isopode (Idotea balthica, Pallas) and the shore crab (Carcinus maenas, Linnaeus.). C. crangon showed an average annual abundance during high water of approximately 80 animals per m-2 (P.POL TE pers. Com.). Pomatoschistus microps and Carcinus maenas showed an average annual abundance of 7 animals m 2 and of 195 animals m-2. An abundance of 26 individuals m-2 was found for I. balthica (P.POLTE pers. Com.). As shown for the seagrass bed, C.crangon, P.microps and C.maenas were also the dominant forms in the tide pools. I. balthica could be found with 26 individuals m-2. The abundance of C. crangon were measured with an Annual average of 157 animals m-2 and therefore showed different results for the seagrassbeds. P. microps and C. maenas showed an average annual abundance of 15 animals m-2 and of 22 animals m-2 respectively. Mobile fauna migrates with the ebb tide into deeper waters (e.g. Pomatoschistus microps.) The substantially lower results of C. maenas within tide pools compared to adjacent seagrass beds can be partly explained by sampling time. In the seagrasbed sampling started earlier in the year (of May), and included the larval and juvenile stages of C. maenas. This led to a substantially higher abundance. Low abundance of I. balthica can be explained by its requirement for a structured habitat. I. balthica needs branched algal structures as a firm substrat. Such structures were hardly available in the tide pools...

Description: In Europe, increased attempts to intensify crayfish aquaculture have been carried out in recent years. Some of the major problems arising from the intensification are related to dietary supply of the animals in culture ponds and tanks. This study therefore focussed on some of the key objectives supporting the development of suitable diets for signal crayfish Pacifastacus leniusculus aquaculture. A large-scale response surface experiment was carried out to study the influences of different macronutrients (protein, lipid, carbohydrate) on crayfish growth and body composition. The results from this experiment led to the development of an improved experimental diet containing high levels of protein and carbohydrates, while increased lipid concentrations seemed to be influencing growth adversely. Further experiments were carried out to improve diet quality. For this purpose, diet types and the suitability of different binding agents were investigated. A small experiment was carried out to monitor the effects of attractants on growth of juvenile signal crayfish. A second objective of this study was the establishment of a new method to measure physiological responses of crayfish to different treatments. Running mid-term or long term experiments require high amounts of resources and slow down the process of dietary development. The measurement of RNA/DNA ratio has proven to be a suitable instrument to examine short-term metabolic responses to different key factors such as feeding regime, diet quality and digestibility and bioavailability of essential nutrients. The study has stressed the importance of proper diet preparation and composition for successful astaciculture. Binding agents were found to have major influence on diet digestibility and bioavailability of macronutrients. As another result of this study, further experiments are regarded to be necessary to examine the response of signal crayfish to different levels of lipid and protein in their diet. Some of the results obtained suggest a lack of regulatory capacity regarding the animals’ protein/lipid ratio. Further experiments however will have to be carried out to proof this hypothesis.

Description: In this study the mean tropospherical total zonal energy fluxes based on the NCEPNCAR reanalyses data are calculated for the time period 1948-2003. The interannual wintertime variability and the vertical structure of the fluxes are analysed. Since the dominant mode of atmospheric variability, the North Atlantic Oscillation, modulates the mean zonal current over the northern Atlantic region on monthly timescales, the NAO is expected to be the main cause for the interannual variability of energy fluxes. This study aims to analyse the linkage between this variabilty of zonal energy fluxes and the NAO. If the interannual variability of zonal energy transport directed to the european continent is associated with the NAO, the interannual energy flux variability can be referred to the variability of atmospheric circulation. In the first section, a climatology shows the three-dimensional structure of the mean zonal energy fluxes and its interannual seasonal standard deviations. In the second section, the dominant patterns of variability in various cross-sections parallel to the circles of longitude are obtained by EOF-analysis. The two leading EOF-patterns show barotropic structures, which in general agree in all sections. The 1.EOF explains more than 50% of the variance, the 2.EOF 25%. There exists however a significant correlation between the principle components only of the first EOFs of the western and eastern cross sections. The connection between zonal fl ux anomalies and the NAO yields a di polar correlationstructure, which is comparable to the correlation-pattern between the NAO and the zonal wind. The barotropic feature is predominant in each cross-section, moreover the regression-patterns show an eastward increasing tilt of the vertical axis towards north with a clear downward propagation of the northern center of activity from the middle troposphere to the lowest levels over Europe. It is shown that the NAO explains more than 30% of the total variance of interannual variability of the seasonal zonal energy fluxes, over the central Atlantic region even more than 40%, whereby anomalies reach up to 30% of the seasonal mean fluxes during extreme NAO-phases. Subsequently, flux anomalies associated with the Niño3-SST are analysed to clarify the dependence upon ENSO. In western parts of the Atlantic region, the Niño3-SST explains less than 5% of the variability of the zonal energy fluxes. Correlations between them are widely non significant in the analysed area. Nevertheless, strong El Niño events tend to cause stronger flux anomalies. In the last section, vertically integrated energy fluxes through the western and eastern boundary of the Atlantic region (represented as 60°W and 0°W longitudes) are computed. Fluctuations of the total energy flux through these sections are proved to be highly correlated with the NAO. The zonal convergence of flux anomalies between the boundaries show weak linkages to NAO, so that meridional atmospheric energy transport anomalies associated with NAO in the Atlantic region are assumed.

Description: The aim of this study is to examine the influence of both thermohaline and wind driven circulation changes on oceanic and atmospheric CO2-concentrations. For this the biopump three- and seven-box models of Toggweiler [1999] are integrated from an interglacial into a glacial steady state and vice versa. In contrast to previous studies which concentrated on steady state situations, here the focus is on transient CO2-concentrations after a sudden change in thermohaline and wind driven circulations. In addition timescales and amplitudes of atmospheric pC02-concentrations during the transition are compared to measurements of ice core datasets.

Description: Studies of animal populations are important and, in the case of harbour seals, have been considered particularly valuable as part of an assessment of the distemper epidemic that has plagued the northern Atlantic population over the last years. Head counts of seals by plane- or ship-based observers are biassed because these animals spent a large percentage of their time underwater. This study seeks to quantify the time that seals can be seen so that head counts can be appropriately corrected. Over the last two years 19 harbour seals were equipped with multiple channel loggers which recorded dive depth every 3-15 seconds for periods lasting up to two month. In this work the diving behaviour of 11 seals, from which the devices could be recovered, was analysed to examine how much time the animals spent at the water surface and on land where they can be counted and the extent to which this varied according to behaviour and water depth. Dives executed conformed broadly to either U- or V-shaped dives according to their profile of depth over time. During U-shaped dives, which comprised about 80% of all dives, the seals always apparently dived to the seabed. Both dive duration and surface duration changed systematically with maximum depth reached during the dive, both increasing: surface time as a cubed function of water depth and dive duration as a squared function of water depth. The percentage time that seals spent at the water surface where they can be seen could described by the equation: % time at surface = (21,55+0,00016( depth)3) / (21,55+0,00016(depth)3)+(156, 7+6,07(1n(depth)2) X 100 Implementation of this formula on seal-counting transects should help in calculations of seal density at sea and thus be useful in population assessments.

Description: Obwohl im terrestrischen Bereich die induzierte Verteidigung durch Herbivore weit verbreitet ist, sind nur wenige Beispiele für marine Makrophyten bekannt. In dieser Studie wurden in zwei Laborexperimenten die Effekte von 1. direktem Fraß durch Amphipoden und 2. wassergetragenen Signalen von Fraß an benachbarten Algen und 3. der Effekt eines benachbarten Konsumenten auf die Antifraßverteidigung von sieben bzw. vier Makroalgen der portugiesischen Südküste untersucht. Die Braunalge Fucus vesiculosus und die Rotalge Sphaerococcus coronopifolius wiesen nach einer Behandlungsphase von 14 Tagen mit drei Amphipodenarten als Konsumenten eine induzierte Verteidigung in intakten Algenstücken auf. Diese Verteidigung wurde innerhalb von zwei Wochen wieder herabgesetzt, nachdem der Fraßdruck reduziert wurde. Für F. vesicu/osus konnte weiter nachgewiesen werden, dass die Verteidigung teilweise auf den lipophilen Bestandteilen der Pflanze beruht. Außerdem konnte für beide Algenarten eine saisonale Variation in der Intensität des Auftretens der Verteidigungsinduktion beobachtet werden. Weiterhin konnte festgestellt werden, dass wassergetragene Signale von 1. benachbartem Fraß sowie 2. von einem benachbarten Konsumenten, der nicht fraß, eine Antifraßverteidigung auslösen. Diese Studie zeigt, dass nicht nur Braunalgen dazu in der Lage sind, auf die Signale von Herbivoren in kürzester Zeit - also innerhalb von 14 Tagen - zu reagieren, sondern dass dies auch bei Rotalgen der Fall sein kann. Nach unserem Wissen ist dies die erste Studie, die zeigt, dass bei Rotalgen eine Verteidigung durch direkten Fraß induziert werden kann und dass wassergetragene Signale von einem nicht fressenden Konsumenten ebenfalls eine Verteidigung auslösen. Hieran ist zu erkennen, dass induzierte Verteidigung durch direkten Fraß wie auch durch wassergetragene Signale in marinen Makrophyten eine größere ökologische Relevanz spielt, als bisher angenommen wurde.

Description: Within the context of the Austrian Climate and Health Tourism Initiative (ACTIVE) this research supports a contribution from scientific basis to the improved use of the healthy effect of climate to Austria. The Central Institute of Meteorology and Geodynamics (ZAMG) provided us climate data records available by stations within of Austria, as well as a synoptical data records available by stations within and outside of Austria. For the investigation period of 1. January 1996 until 31. December 2000 series of measurements of 201 climatic stations and 278 synoptical stations are available. Emphasis of the analysis is the comparison of these two station types on the basis of the Physiological Equivalent Temperature (PET). It considers the influences on the Energy Balance of Humans by air temperature, vapour presssure, wind velocity, as well as short and long-wave radiant fluxes from the environment to the human body as the mean radiant temperature. This characteristic is to be modelled by RayMan, a modell for the mean radiant temperature and thermal indices in urban structures and divided into individual temperature ranges according to the unit degrees Celsius. It makes a classification possible which can be set into relation to comfort stages. The confrontation of both station types at midday takes place via frequency distributions from PET classes concerning the calendar months in per cent and in days per year. This time of day is for tourists and healthy oriented people decisive of choosing an climatic adequate region which is caused of a high activity rate in this hours. Further a regionalization is accomplished based on a regression analysis. This method places PET in relationship with geographical latitude, geographical length, height over the sea level, slope, aspect ratio and land use. So it makes the transferring of PET into the space possible. The generated maps show both the PET distribution in the calendar months and the distribution of individual classes based in each case on climatic and synoptical data records. The maps include a description of the bioclimate and makes a regional comparison of both data records possible. It shows similarly spatial and temporally tendencies in both kind of data records which have nearly the same high significant regression coefficients. A smaller data lack in climate data records and different measurement times at 14 o’clock LST for climate stations and at 13 o’clock CET for synoptical stations cause minor changes which can be observed in the mean radiant temperature and air temperature of both kind of stations. They lead to a lower PET in maps generated by synoptical data records. At all both show more detailed maps with a high resolution of 1 km as it was possible in former studies.

Description: The presentwork describes fields of UV-radiances at ground level from the simulation of a Monte-Carlo radiative transfer model as well as the differences of these to observed values. The optical properties of the atmosphere, like the albedo, the single scattering albedo and the Aerosol Optical Depth, were varried, in order to minimize the differences compared with the obbserved radiances. Maximum differences occure with viewing angles towards the sun, which did not become balanced also by the variation of the initial parameters into the model. These are partially due to the smoothing of the measured data in this direction. It could be obtained a optimal agreement without the the sun direction by taking absorbing aerosol particles into account. The difference with viewing angles in the direction of the sun bcomes recognizable in the strewing diagram. The use of observed atmosphere profiles of the huminty, ozone and the aerosols in the radiative transfer model do not supply th most optimal agreement with the measured radiances. It is an agreement with inconsistent behavior, since no uniform atmosphere condition for each wavelength could be found.

Description: Die Analyse der chemischen Mikrostruktur von Fisch-Otolithen ist eine verhältnismäßig moderne Methode, die die Rekonstruktion der Lebensgeschichte gefangener Fische ermöglicht und Informationen über Wanderverhalten und Verbreitung der Fische liefert. Voraussetzung dafür ist allerdings die genaue Kenntnis der Einflüsse sämtlicher Umweltfaktoren auf die Elementzusammensetzung der Otolithen. Im Rahmen dieser Arbeit wurden die Einflüsse von Salinität und Temperatur auf das Sr/Ca-Verhältnis der Flunder (Platichthys flesus) erstmals untersucht. Hierzu wurden die Sr/Ca-Verhältnisse der Otolithen von Flundern aus drei verschiedenen konstanten Salinitäten (22, 17, 12 psu) verglichen. Ein entsprechender Versuch erfolgte mit drei verschiedenen Temperaturen (22°, 19°, 15°C). In beiden Versuchen war kein signifikanter Einfluss des jeweiligen Umweltfaktors auf das Sr/Ca-Verhältnis nachweisbar. Einen deutlich größeren Effekt hatten die individuellen Unterschiede zwischen den Sr/Ca-Verhältnissen einzelner Fische aus identischen Bedingungen. In zwei weiteren Versuchen erfuhr die Salinität, bzw. die Temperatur in einem ähnlich kleinskaligen Wertebereich eine stetige Veränderung. Die Ergebnisse der Versuche zeigten für beide Umweltfaktoren einen positiv korrelierten Zusammenhang zum Sr/Ca-Verhältnis. Der beobachtete Einfluss der Salinität war jedoch eindeutiger zu erkennen. Die Ergebnisse zeigen, dass Flundern sich sehr effektiv in ihrer Osmoregulation an längerfristige Änderungen in den Umweltbedingungen anpassen können. Für ergänzende Untersuchungen wurden Flundern aus der Ostsee in Süßwasser gehalten. Dieser Versuch zeigte, dass großskalige Salinitätsunterschiede auch von der Flunder nicht kompensiert werden können, so dass die Analyse des Sr/Ca-Verhältnisses von Flunder-Otolithen zumindest der Rekonstruktion von Wanderungen entlang eines starken Salinitätsgradienten dienen kann. Zusätzlich wurden juvenile Sprotten ( Sprattus sprattus) veränderten Salinitäten ausgesetzt und ein positiv korrelierter Bezug zwischen der Salinität und dem Sr/Ca-Verhältnis der Sprott-Otolithen gefunden. Weiterhin konnten Wanderungen zwischen Gewässern stark unterschiedlicher Salinität, anhand der Sr/Ca-Verhältnisse der Otolithen, für mehrere Aale (Anguilla anguilla) und Flussbarsche (Perca fluviatilis) rekonstruiert werden. Otolithenbereiche, die in Süß-, Ostsee- oder Atlantikwasser gebildet wurden, konnten dabei sicher unterschieden werden. Es wurden außerdem deutliche artspezifische Unterschiede in den Sr/Ca-Verhältnissen der untersuchten Fischarten gefunden. Dies bedeutet für zukünftige Freiland-Studien, dass für jede zu untersuchende Fischart eine eigene Kalibration der Zusammenhänge zwischen Umweltfaktoren und Elementzusammensetzung der Otolithen, unter Laborbedingungen durchzuführen ist.