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The effects of stratospheric ozone depletion and of global warming on the marine biosphere are still underexplored, especially in the Arctic. Seaweeds are very important primary producers but are strongly susceptible to enhanced UV radiation and elevated temperatures, especially their spores. The UV susceptibility of spores has previously been invoked to determine the depth distribution of seaweeds. Therefore, we will investigate the effect of different radiation and temperature conditions on the ultra-structure, physiology and biochemistry of spores from various brown and green algae growing in different water depths. Moreover, we will study competition between zoospores of various species of brown macroalgae in order to get an insight about biotic factors structuring seaweed communities and also to explain more clearly the present seaweed zonation pattern.
Plankton of shallow polar freshwater water bodies is exposed to increasing levels of ultraviolet radiation (UVR) due to the limited water depth. Daphnia (Crustacea, waterflea) and algae are common representatives of the food chain in these water bodies. Daphnia almost exclusively use lipids for energy storage, which they obtain from their food (mainly algae). Therefore, Daphnia and algae are closely linked to each other. Preliminary experiments on the UV-induced damage in phyto- and zooplankton point to lipids as one of the key players. With this application we want to identify how algae specific lipids and fatty acids (FA) are modified by UVR. The factors modifying UV-doses to the animals and their food are depth of the waterbody and DOC (absorbs UV). A pondsurvey shall provide a wide spectrum on ponds which vary in DOC and depth. Lipid analysis of Daphnia and their food of these ponds as well as physical parameters of the pond waters shall identify correlations between UV-exposure and specific fatty acids. This shall enable us to estimate the effect of solar UVR on the freshwater plankton community in polar ponds.
The succession of macro- and microalgal communities in the Antarctic will be investigated in field experiments under various UV radiation (UVR) conditions and in the absence or presence of grazers. The observed differences in the succession process will be correlated to physiological traits of single species, especially in spores and germlings, which are the most vulnerable stages in their life histories. Photosynthetic activity of the different developmental stages will be measured routinely. Additionally we plan the determination of pigment composition, C:N ratios, content of UV protective pigments and of possible DNA damage. The experiments will start in spring, concomitant to the time of highest UVBR, due to the seasonal depletion of the ozone layer in the Antarctic region. Supplemental laboratory experiments will be conducted to determine the effects of UVR on spores and germlings of individual species. In addition to the above analyses, we plan to examine of UVR induced damage of cell fine structure and of the cytoskeleton. The results of both the field and laboratory experiments will allow us to predict the consequences of enhanced UVR for the diversity and stability of the algal community.
Detection of UV-B induced DNA damage on zoospores of brown algae
The aim of this project is to investigate natural products from polar macroalgae. As arctic waters represent an extreme habitat, formation of secondary metabolites is limited - besides other factors - by light conditions. Therefore, the influence of light, particularly different photon fluence rates and UV radiation, on secondary metabolism and on regulation of associated genes will be studied.
Observation how UV-radiation affects recruitment on hard substrate in the upper sublitoral zone.
In preparation to the launch of the SAGE III experiment in March 2001, NASA and the European Union performed the SOLVE / THESEO-2000 campaign, which had three components: (i) an aircraft campaign using the NASA DC-8 and ER-2 airplanes out of Kiruna/Sweden, (ii) launches of large stratospheric research balloons from Kiruna, (iii) validation excercises for the commissioning phase of SAGE III. The German Arctic research station Koldewey in Ny-Ålesund/Spitsbergen contributes to (i), (ii), and (iii) by performing measurements of stratospheric components like ozone, trace gases, aerosols (PSCs), temperature and winds. The measurement results were transmitted quasi online to the flight planning center in Kiruna, in order to allow a better directing of the air plane flights. In addition the Koldewey-Station has been designated a validation anchor site for the SAGE III validation. The activities are organized within a NASA accepted proposal of ground-based validation support by the NDSC Primary Station at Ny-Ålesund, Spitsbergen and by a SAGE III validation working group for Ny-Ålesund. The main observation periods are from December 1999 to March 2000.
In order to get detailed vertical ozone profiles above the range of standard electrochemical ozonesondes (typically 35 km), a radiosonde together with an optical ozonesensor is launchend with a special plastic foliage balloon. The balloon payload consists of a digital radiosonde (DFM 90) using GPS for altitude measurements and a two channel filter spectrometer (optical sensor) to measure the vertical ozone distribution up to more than 40 km altitude. The ozone profiles obtained by the optical sensors will be compared with ground-based microwave and lidar ozone observations as well as with the standard balloon-borne ozone measurements with electrochemical ozone sensors.
The objective of the planned work with arctic higher plants is to study the range of adaptation of photosynthetic metabolism, of antioxidative and sun screen compounds in a cold and reduced UV-B climate in comparison of data already raised from high alpine plants, which live partially under stronger cold and under different light regimes, especially higher UV-B. Further, the ultrastructure of leaf cells will be studied to clear, whether adaptations found in some high alpine plants occur similarly in arctic plants, and to connect such cytological results with metabolic functions. An additional comparison will be made with snow algae from Svalbard compared to those harvested on high alpine snow fields. It is the advantage of the planned work, that a number of investigations ranging from ultrastructural studies over different aspects of photosynthesis to assays of UV-B sensitive compounds and antioxidants will be conducted mostly with measurements and sample collection in the field during the same experimental day at one place. Therefore we expect a good connection of the data raised, back to the plant system and expect a much broader description of vitality and adaptation under the current conditions.
Photoinhibition of photosynthesis by UV radiation, the formation of UV-screening pigments, DNA damage by UV radiation as well as DNA repair mechanisms will be determined in marine macroalgae of the Kongsfjord. Moreover, algae from different water depths will be transplanted by divers into areas with opposite light climate or covered by UV-screening filters and their physiological reactions tested. Additionally, the susceptability of the unicellular algal spores to UV-radiation will be tested. The results will allow insights into the effect of UV and photosynthetically active radiation on the zonation of macrocalgae and on the structure of phytobenthic communities. The data will be used to model the effects of increased of UV-radiation due to stratospheric ozone depletion on the Kongsfjord phytobenthic communities.
The changes in the stratospheric ozone layer due to anthropogen emissions lead to an increasing insolation of sunlight in the UV-B range (280nm - 320nm) on ground. One of the major objects of UV-B measurements is to detect long-term trends. The most interesting areas corresponding to ozone depletion are Antarctica and more recently the region around the northern pole. In interdisciplinary cooperation the data are also basis for research in the effects of increasing UV-B doses on plankton, algae, and other organisms. Since 1998 additional measurements of UV-A radiation (320-400nm) are done.
The Baseline Surface Radiation Network (BSRN) is a cooperative network of surface radiation budget. Measurement stations operated by various national agencies and universities under the guiding principle set out by the World Climate Research Programme (WCRP). Presently about 15 stations have been established, one of them is Ny-Ålesund. The concept for a Baseline Surface Radiation Network has developed from the needs of both the climate change and satellite validation communities. The aims of the programme are the monitoring of long-term trends in radiation fluxes at the surface and the providing validation data for satellite determinations of the surface radiation budget. The BSRN station Ny-Aalesund was installed in summer 1992 and is regularly operating since August 1992.
This study will be designed to determine the response mechanisms of representative species of macrophytes along the tide flat to provide the physiological basis for answers for ecological questions, in particular how the community structure of various beds of macroalgae from the intertidal to the subtidal (eulittoral to sublittoral) region of the coastal ecosystem is affected by enhanced UV radiation. In situ measurement of photosynthetic efficiency, growth, community structure and succession will be conducted to investigate how do different species of macrophytes respond to changes in the light environment over a depth gradient and across seasons of the year. It is hypothesized that the differences in the ability to tolerate stress are the main factors controlling the distribution pattern of macrophytes. With the limited understanding in the control of tolerance, elucidating the mechanism of stress in the physiology and ecology of the organisms will allow us to quantify the impediments encountered by organisms inhabiting the tide flats. Objectives: 1. To measure the daily and seasonal variation in photosynthetically active and ultraviolet radiation. 2. To characterize the macrophyte community structure of the coastal habitat. 3. To perform UV exclusion and UV supplementation experiments in order to assess its effect on the growth of some macrophyte species in the field and in mesocosms. 4. To assess the prevention of UV damage in selected macroalgae by production of sunscreen pigments. 4. To determine the recruitment rate, recolonization pattern and succession under PAR and varying UVR condition.
Due to its high energy, UV radiation can induce severe damage at the molecular and cellular level. On the molecular level proteins and lipids, as well as nucleic acids are particularly affected. Conformation changes of certain proteins involved in photosynthesis, such as the reaction center protein (D1) of photosystem II or the CO2 fixing enzyme in the Calvin cycle (RuBisCo) lead to an inhibition of photosynthesis, and consequently to a decrease in biomass production. This might shift certain algal species into deeper waters, not reached by UV radiation. The aim of the studies is to demonstrate how strong an increase of UV radiation due to stratospheric ozone depletion will influence the depth distribution and biomass production of macroalgae, and which molecules and processes are most severely affected. Moreover, it will be studied, which stage in the life cycle of the individual species is most sensitive to UV radiation as it will be this particular stage, which in the end determines the upper distribution limit of a certain species on the shore.
SAGE III was successfully launched on 10. Dec. 2001 on a Russian M3 rocket. It provides accurate data of aerosols, water vapour, ozone, and other key parameters of the earth's atmosphere. The science team of the SAGE III experiment at NASA has nominated the Koldewey-Station as an anchor site to contribute within the Data Validation Plan as part of the Operational Surface Networks. Data directly relevant to the SAGE III validation are aerosol measurements by photometers and lidar, as well as temperature measurements and ozone profiling by balloon borne sondes, lidar and microwave radiometer. Data will be provided quasi online for immediate validation tasks.
In preparation to the launch of the SAGE III experiment in March 2001, NASA and the European Union performed the SOLVE/THESEO-2000 campaign, which had three components: (i) an aircraft campaign using the NASA DC-8 and ER-2 airplanes out of Kiruna/Sweden, (ii) launches of large stratospheric research balloons from Kiruna, (iii) validation exercises for the commissioning phase of SAGE III. The German Arctic research station Koldewey in Ny-Ålesund/Spitsbergen contributed to (i), (ii), and (iii) by performing measurements of stratospheric components like ozone, trace gases, aerosols (PSCs), temperature and winds. The main observation periods were from December 1999 to March 2000.
The stratospheric multi wavelength LIDAR instrument, which is part of the NDSC contribution of the Koldewey-Station, consists of two lasers, a XeCl-Excimer laser for UV-wavelengths and a Nd:YAG-laser for near IR- and visible wavelengths, two telescopes (of 60 cm and 150 cm diameter) and a detection system with eight channels. Ozone profiles are obtained by the DIAL method using the wavelengths at 308 and 353 nm. Aerosol data is recorded at three wavelengths (353 nm, 532 nm, 1064 nm) with depolarization measurements at 532 nm. In addition the vibrational N2-Raman scattered light at 608 nm is recorded. As lidar measurements require clear skies and a low background light level, the observations are concentrated on the winter months from November through March. The most prominent feature is the regular observation of Polar Stratospheric Clouds (PSCs). PSCs are known to be a necessary prerequisite for the strong polar ozone loss, which is observed in the Arctic (and above Spitsbergen). The PSC data set accumulated during the last years allows the characterization of the various types of PSCs and how they form and develop. The 353 and 532 nm channels are also used for temperature retrievals in the altitude range above the aerosol layer up to 50 km.