Description: This thesis provides a comprehensive assessment of the response and vertical distribution of major components of the pelagic ecosystem and highlights the species interactions shaping this open ocean environment and its associated biogeochemical cycles.During the iron fertilization experiment (EisenEx), carried out in the Polar Frontal Zone of the Southern Ocean in austral spring (November), the composition, succession and temporal development of the nano-, microprotozooplankton (protozoa between 2 and 20 µm and 20 and 200 µm respectively), mesozooplankton (protozoa 〉 200 µm) and small metazooplankton (copepod nauplii, copepodites and adults of small species) assemblage was successfully followed for three weeks and compared with non-fertilized, surrounding water. The grazing impact of microprotozooplankton on the natural phytoplankton assemblage was also studied under controlled conditions using the dark incubation method. These experimental results combined with data on microphyto- and microprotozooplankton composition and temporal development were used to estimate microprotozoan grazing impact on primary producers, in particular the diatoms, during the fertilization experiment. The temporal development of particles produced by proto and small metazooplankton (empty diatom frustules, fecal pellets, skeletons and empty loricae) and their contribution to carbon and silica vertical fluxes during EisenEx were also investigated.Key words: Polar Frontal Zone; EisenEx; protozooplankton; small metazooplankton; iron fertilization; temporal development; vertical fluxes; grazing impact; copepod nauplii; small copepods, microphytoplanktonDistinct differences in microprotozoan assemblage inside and outside in relation with the phytoplankton bloom development were not observed. The microprotozooplankton population was dominated by dinoflagellates followed by ciliates. Dinoflagellates showed a ~ three-fold increase in abundance and biomass in the first 10 d of the experiment inside the patch, but decreased thereafter to about two-fold higher values compared to pre-fertilization values. The decline after day 10 indicates increasing grazing pressure by copepods. Dinoflagellate population was dominated by small sized (20-40 µm) athecate dinoflagellates which comprised up to 58 % of population stocks suggesting that also food limitation could be a further explanation for the strong decrease since the phytoplankton bloom was dominated by long chain-forming diatoms in the second half of the experiment which are not available for these dinoflagellates as food source. Ciliate abundances increased only slightly due to heavy grazing pressure by copepods, but biomass doubled with the majority of the increase caused by a three-fold increase in aloricate choreotrichs.Grazing impact by microprotozoa estimated for EisenEx showed that microprotozoa consume only a rather small fraction of primary production, including the diatoms (6 to 18 % of primary production grazed d-1, corresponding to 3 to 9 % of diatom daily carbon stock). Grazing rate on other phytoplankton (without diatoms) was relatively higher accounting for 9 to 28 % of other phytoplankton carbon stock d-1. Thus, microprotozooplankton grazing strongly affected nanoplankton populations, but was low on the diatom assemblage.Tintinnids, thecate dinoflagellates, foraminifera, radiolarian and acantharia comprised the bulk of larger (〉 50 µm) protozoan assemblage. Inside the patch, acantharian numbers increased three-fold, but only negligibly in surrounding waters. This is of major interest, since acantharia are suggested to be responsible for the formation of barite found in sediments and which is possibly a paleoindicator of high productivity regimes. Foraminiferans also increased significantly in abundance, however the marked increase of juvenile individuals after a full moon event suggests a lunar periodicity in the reproduction cycle of some foraminiferan species rather than a reproductive response to enhanced food availability. Larger thecate dinoflagellates almost doubled in numbers and biomass, but also showed an increase outside the patch. In contrast, adult radiolaria showed no clear trend during the experiment, but juveniles increasing three-fold indicating elevated reproduction. Tintinnids decreased two-fold, whereas their carbon stocks remained more or less constant caused by a change in the relative importance of species. Empty tintinnid loricae, however, increased by a factor of two indicating that grazing pressure on this group intensified during EisenEx. In mixed layer (0 to 80 m depth), overall vertical distribution followed mainly vertical distribution of potential prey particles. The stocks of larger protozoa in the surface layers was negligible when compared to the rest of the protozoa and zooplankton. Below 80 m, biomass was dominated by foraminifera indicating important influence on biological processes occurring below the mixed layer during EisenEx.Within the small metazoans, copepod nauplii numbers stayed more or less constant, whereas biomass doubled indicating individual growth during EisenEx. Numbers of small sized copepodites and adults of cyclopoids (predominantly Oithona similis) and small calanoid copepods (predominantly Ctenocalanus citer) increased ~ three-fold suggesting either a enhanced recruitment from naupliar and copepodite stages, respectively, and/or an accumulation of numbers due to migration of individuals from below the mixed layer into the upper water column caused by a diet shift.Particles produced by proto- and metazooplankton during this study showed an increase in the course of the experiment and were correlated to the vertical distribution of their producers. Protozoan fecal pellets were significantly correlated to athecate dinoflagellates indicating that they were mainly responsible for fecal pellet production. The dominance of olive green ellipsoidal to spherical pellets discriminated during EisenEx suggest that particularly larger protozoan were also actively involved in either re-ingestion and repackaging of larger metazoan pellets. Copepods were the main source of large recognisable metazoan fecal pellets as indicated by the dominance of compact cylindrical pellets characteristic for copepod feces. Both protozoan, metazoan fecal pellets, empty diatom frustules and empty tintinnid loricae showed very high abundances as compared to radiolarian skeletons. Comparison with metazoan fecal pellet abundance indicate that contribution of protozoan fecal pellets and empty diatom frustules to total vertical fluxes could be significant, despite low sinking rates.

Description: During the iron fertilization experiment EisenEx conducted in the Antarctic Polar Frontal Zone the response of the plankton community to iron addition was studied in detail. Within the diatom assemblage four major response types could be distinguished inside the fertilized patch. Fast growing and weakly silicified diatoms like Pseudo-nitzschia lineola and Chaetoceros curvisetus exhibited exponential growth rates throughout the experiment. The heavily silicified species Fragilariopsis kerguelensis and Thalassionema nitzschioides showed an initial phase with negligible growth during the first week followed by a linear increase in abundance thereafter. Two large solitary and weakly silicified diatoms, Haslea sp. and Corethron pennatum, exhibited a linear growth with no initial lag phase. The small diatom species Nitzschia sp. and Cylindrotheca closterium were characterised by an initial linear increase and a decline during the second half of the experiment. The response of major components of the non-diatom phytoplankton assemblage, including Phaeocystis antarctica, phototrophic dinoflagellates, coccolithophores and Dictyocha speculum, to iron addition accounted for only a minor iron-induced biomass increase. In addition to life diatom cells intact empty and broken diatom frustules were also accounted for in this study as indicators of diatom mortality. The increase of both broken and intact empty frustules inside the patch indicates an increased grazing pressure by proto- and metazoen grazers. The vertical distribution of non-motile particles and planktonic organisms comprises another important aspect of this study. Whereas motile planktonic organisms are able to regulate their position in the water column by active swimming non-motile particles will eventually sink out of the surface layer. Various processes affect the composition and magnitude of non-motile particles of biological origin of which grazing seemed to have played the major role during this study.

Description: The present study aimed to know the influence of five phytoplankton species on the feeding behavior, reproduction and survival of the copepod A. tonsa. Biochemical parameters (total lipid, carbohydrate and protein) were measured to know the possible nutritional value of the diet. The species were offered to A tonsa as single and mixed diet. The species used were the flagellates C. acantha and R. baltica, the potentially toxic dinoflagellates A. tamarense and P. lima and the diatom S. costatum. Protein (55-69%) was the major biochemical components per cell volume, following for carbohydrate (17-31%) and lipid (13-18%). The concentration of the biochemical components measured per cell volume influenced the hatching success and survival of the adults. The hatching success was correlated with the egg production and ingestion rate of the copepod and survival of the early stages. No correlation was found between egg production and the biochemical concentration per cell volume. The biochemical components per cell volume showed a high interspecific difference between the species and seemed to better explain part of the nutritional value of the phytoplankton, as the concentrations per dry weight and volume medium. The copepod A tonsa had a selective feeding behavior feeding preferable on S. costatum and R. baltica in the mixed food. The ingestion rate of the specie C. acantha was reduced into the mixed food. The size range of the species offered to A. tonsa did not influence its ingestion rate.The flagellates R. baltica and C. acantha and the mixed food provided the best effects on the reproduction and survival of A. tonsa. The best results among the single foods treatments were found with the alga, with the higher lipid content (R. baltica and C. acantha). The dinoflagellates P. lima all showed eggs production and good hatching but, the survival of adults and early stages was affected. S. costatum prevented egg production. The survival and reproduction of A. tonsa fed on A. tamarense was reduced and comparable to the control (without food). In spite of, no influence was seen when S. costatum, P. lima and A. tamarense were offered mixed with the two flagellates. The mixed food was the best food. This result could demonstrate that the negative effect of these species on the reproduction and survival of A. tonsa was due their insufficient biochemical content as the presence of toxin. A good food muss proved not only a good egg production and hatching success, but a high the survival of the first stages, guaranteed the survival of the organism in the environment. The negative effect of the dinoflagellates on the survival of the early stages of the copepod indicated that these species were a bad food for A. tonsa. Therefore, A. tamarense, S. costatum and P. lima were no a good diet as single food to A. tonsa. The best results with the mixed food could be result from an increase on the levels of DHA, provided for R. baltica, and EPA, provided for S. costatum, also as for the increase of protein supplied for C. acantha, major content of protein per cell volume. But for a better understand of the relation of the biochemical contents with survival e reproduction of aquatic animals makes necessary a analysis of vitamins, minerals and of the constitutes of each gross biochemical composition, such as fatty acids, amino acids, sterols, sugars.

Description: Juvenile and adult Loligo opalescens Berry were video taped in Monterey Bay with the remotely operated vehicle (ROV) Ventana,captured with an otter trawl in Santa Monica Bay, California, and adults were taken from the Monterey Bay fishery. Behavioral observations were made over a 13 h period of video sequences. Allometry measurements were made on 157 squids ranging in size from 12 to 151 mm mantle length (ML). In addition to ML we measured the morphometric characters of fin length(FL), fin width (FW), mantle width (MW), eye diameter (ED), head width (HW), funnel aperture diameter(FA), fourth arm length (AL) and tentacle length(TL). Loligo opalescens changes shape with ontogeny due to negative allometric growth of ED, HW, TL, MW, FA and positive allometric growth of AL, FL and fin area. The allometry measurements were used to determine the size of juvenile squids video-taped in open water. A linear regression can predict dorsal ML in mm from a dimensionless ratio of ML upon ED (r2=0.857, P〈0.001). Sizes and velocities of video-taped animals were estimated from 26 video sequences ranging from 〈1.0 to 8 s. The average velocity for squids ranging from 12–116 mm ML was 0.21 m s–1 and the maximum velocity was 1.60 m s–1(116 mm ML). Allometric measurements can provide scale for 2-dimensional images in order to estimate size, velocity and age of animals.

Description: This study is the first detailed assessment of A. palmata populations of the Turks and Caicos Islands. A total of 203 individual colonies and 62 thickets were tagged on five shallow reefs. Depth, percentages of living tissue, recent mortality and old skeleton were estimated. Presence of disease and predatory snails was noted, and disease spread and grazing rates of the snails estimated. Colonies were found in depths of 0.2 - 4 m. Living tissue for individual colonies (75.9% ± 2.2 SE) was significantly greater than for thickets (58.6% ± 3.6) and in both cases exceeded old skeleton (individuals: 22.7% ± 2.1 SE, thickets: 38.0% ± 3.4 SE). Percentage of recent mortality was very low (individuals: 1.3% ± 0.3 SE, thickets: 3.4% ± 0.7%). We found WBD (n = 2), white pox disease a (WPDa) (n = 7) and white pox disease b (WPDb) (n = 14) with greatly varying spreading rates. The WBD infected colonies showed an atypical spread from the top of the branch towards the base. Coralliophila abbreviata and C. caribaea affected 3 .7 54.7% of the populations (grazing rate: 4.29 cm 2 /day/snail ± 1.16 SE). South Caicos’ A. palmata populations are still in good condition, though increasing human disturbances combined with disease and predatory snails may threaten these populations.

Description: An increasing number of publications about theoretical approaches and new findings illustrate the relevance of the topic environmental risk assessment. The actual discussion about high oil prices is not incorporated under this headline; but it should be, as natural resource scarcity is a crucial economic factor. In practical experience, more and more banks, insurance companies as well as investors realize that there are certain areas with a high correlation between sustainable development and corporate success, corporate risk exposure and corporate performance. In this discussion one of the most obvious topics are risks related to climate change. According to the findings of surveys evaluated in this paper climate change starts to affect economic development and companies' performance in various ways. Over the next decade, economic losses due to climate change are estimated by US$ 150 billion per year. As result world's business leaders have described climate change as the biggest challenge of the 21st century. Hence, the incorporation of climate change as a risk factor is essential, but risks related to climate change feature a severe issue of complex structure and uncertainty; traditional risk assessment tools appear in the light of not being able to either reflect the multifaceted system nor provide sufficient outcomes. Environmental risk assessments in general so far have mainly emphasized - if at all - on actual and possible impacts of the release of materials or emissions (external effects). But an overall sustainable risk assessment has also to take into account the risks related to the inflow of materials. The main reason for neglecting the inflow risks from an environmental perspective can be seen in the fact that these risks seem to be less tangible and more uncertain. Nevertheless, in a world where economic development and the use of natural resources is not uncoupled yet, a steadily increasing economic power will result in a continually rising extraction of resources. As all resources are limited, the risk of scarcity will rise; and the example of water illustrates that it already exists. Indeed, scarcity is not tangible for all kind of resources from a present point of view. Hence, a specified analysis is needed considering different market and supply conditions. A comprehensive analysis of environmental risks needs to encompass risks affecting the output as well as the input side of a value chain. This paper enlarges the discussion on environmental risk assessments upon the input dimension using the example of carbon risks. Firstly, carbon risks are defined as risks related to climate change at the corporate level with a focus on the input as well as the output dimension. Secondly, an analysis of the current discussion on the topic of carbon risk evaluates the status quo of scientific work in this field. Thirdly, in terms of developing a practically oriented tool, the Value-at-Risk approach and it's application to measure input oriented carbon risks are scrutinized. The results discuss how future volatility and market prices can be utilized to describe the uncertainty resulting from markets acknowledging and pricing oil scarcity as a risk factor. Finally recommendations with a focus on strategic management decisions and financial performance analysis are given and further research opportunities are drawn. The conclusion is; once markets have acknowledged the depletion mid-point as a measure of oil scarcity, natural scarcity will result in a significant higher Value-at-Risk. The Value-at-Risk of one barrel of crude oil could then be as high as US$ 15.5 in the short term and even US$ 17.2 in the long term. The scope of this paper is neither intended to predict one likely development nor to demonstrate how this tool can actually work in terms of forecasting single companies' performance. But in order to point the way ahead, this paper provides scenarios for potential future developments and sets a frame for risk assessments due to oil scarcity.

Description: The expedition ARK XIX/3 with the German icebreaking RV "Polarstern" was jointly organized between the Alfred Wegener Institute for Polar and Marine Research (AWI) and the Institut Français de Recherche pour l'Exploitation de la mer (IFREMER), the latter providing the unmanned deep-sea submersible "Victor 6000". AWI and IFREMER offered this unique combination of infrastructure in 2003 to European scientists to permit access on advanced technology in marine research to a broader community. Therefore, this cruise was not only a milestone in the Franco-German cooperation but also an important contribution to the European marine research initiatives. All still pictures and videos taken with "Victor 6000" during the expedition "VICTOR IN THE NORTH" are joint property of AWI and IFREMER with copyright by IFREMER. This material can be used for scientific purposes with the indication of IFREMER's copyright. It would be very much appreciated if the joint effort of AWI and IFREMER in organising the cruise ARK XIX/3 would be mentioned in the acknowledgements of any future publication written on the basis of material collected during the expedition. Any commercial or other than scientific use of either pictures or videos collected with "Victor 6000" needs the written formal approval of IFREMER. The entire cruise report is also available in digital format on a CD-ROM attached to this booklet because many of the pictures and graphs are in colour. All hand written dive log files are permanently stored at the AWI. For a certain period of time the cruise diary will be still accessible via the internet at www.polarstern-victor.de.