Auf den Spuren von Robert Scott's Terra Nova Expedition - Botanische Untersuchungen In Botany Bay, Granite Harbour, Süd Victoria Land, Kontinentale Antarktis

Die Terra Nova Expedition (1910-1913) von Robert Falcon Scott wird bis heute überschattet von dem tragischen Ende des Vorstoßes zum Südpol, den Scott mit seinen vier Begleitern im Januar 1912 - einen Monat nach Amundsen - erreichte. Dabei gerat leicht in den Hintergrund, daß neben dem Vorstoß zum Pol umfangreiche wissenschaftliche Untersuchungen einen wichtigen Schwerpunkt der Expedition bildeten. So wurden zahlreiche meteorologische, geologische und biologische Untersuchungen und Erkundungen von mehreren, unabhängig voneinander operierenden, wissenschaftlichen Feldgruppen durchgeführt. Eine dieser Feldgruppen war die Western Geological Party', die im Sommer 1911/12 unter der Leitung des Geologen Griffith Taylor von Granite Harbour ausgebend, einem tiefen natürlichen Hafen auf 77°S, die Küste von Süd Victoria Land erkundete. Die Forschungsergebnisse mit Hinweisen auf eine außergewöhnlich reiche Vegetation wurden im Reisebericht der Terra Nova Expedition bereits 1913 veröffentlicht (TAYLOR 1913). Aufgrund seiner abgeschiedenen Lage ist dieses Gebiet seitdem jedoch nur sehr selten besucht worden und in Vergessenheit geraten, ast 1989 wurde die außergewöhnlich reiche Vegetation wiederentdeckt

Terrestrisch-ökologische Expedition nach der Station H. Arctowski (King George Island)

Auszug aus einem Arbeitsberich

Erfolg bei der IBO Challenge 2020

Die Endrunde der Internationalen BiologieOlympiade 2020, die eigentlich mit Schülerinnen und Schülern und ihren Betreuerteams aus mehr als 75 Ländern im japanischen Nagasaki stattfinden sollte, konnte wie viele andere Veranstaltungen aufgrund der Reisebeschränkungen durch COVID-19 nicht wie geplant durchgeführt werden. Stattdessen hatten die japanischen Organisatoren eine „IBO Challenge 2020“ vorbereitet, an der das deutsche Team mit vier Medaillen und einem Champion Award erfolgreich teilnahm

Fourteen degrees of latitude and a continent apart: comparison of lichen activity over two years at continental and maritime Antarctic sites

There are marked declines in precipitation, mean temperatures and the number of lichen species with increasing latitude in Antarctica. However, it is not known which factors are the predominant controllers of biodiversity changes. Results are presented from over two years of almost continuous monitoring of both microclimate and activity in lichens at Livingston Island, South Shetland Islands, 62°S, and Botany Bay, Ross Sea region, 77°S. Lichen activity was evident over a much longer period at Livingston Island, (3694 versus 897 hours) and could occur in any month whereas it was almost completely confined to the period November–February at Botany Bay. Mean air temperatures were much lower at Botany Bay (-18° compared to -1.5°C at Livingston Island), but the temperatures at which the lichens were active were almost identical at around 2°C at both sites. When the lichens were active incident light at Botany Bay was very much higher. The differences are related to the availability of meltwater which only occurs at times of high light and warm temperatures at Botany Bay. Temperature as a direct effect does not seem to explain the differences in biodiversity between the sites, but an indirect effect through active hours is much more probable. In addition there are negative effects of stresses such as high light and extreme winter cold at Botany Bay

The moss Bryum argenteum var. muticum Brid. is well adapted to cope with high light in continental Antarctica

The net photosynthetic rate (NP), chlorophyll fluorescence, carotenoid content and chlorophyll content of the cosmopolitan moss Bryum argenteum were measured in the field at Botany Bay, southern Victoria Land, continental Antarctica (77°S). Comparisons were made between sun- and shade-adapted forms, and changes were followed as the moss emerged from under the snow and during exposure of shade and sun forms to ambient light. Shade forms had lower light compensation and saturation values for NP but little difference in maximal NP rates. Shade forms exposed to ambient light changed rapidly (within five days) towards the performance of the sun forms. Surprisingly, this change was not by acclimation of shoots but by the production of new shoots. Chlorophyll and carotenoid levels measured on a molar chlorophyll basis showed no difference between sun and shade forms and also little change during emergence. The constant molar relationship between carotenoids and chlorophyll plus the high levels of the xanthophyll cycle pigments suggest that protection of the chlorophyll antenna was constitutive. This is an adaptation to the very high light levels that occur when the plants are active in continental Antarctica and contrasts to the situation in more temperate areas where high light is normally avoided by desiccation

Photosynthetic performance of Xanthoria mawsonii C. W. Dodge in coastal habitats, Ross Sea region, continental Antarctica

Xanthoria mawsonii C. W. Dodge was found to perform well physiologically in a variety of habitats at high latitudes in continental Antarctica. The net photosynthetic rate of 7•5 μ mol CO2 kg−1 s−1 is exceptionally high for Antarctic lichens. Field and laboratory measurements proved the photosynthetic apparatus to be highly adapted to strong irradiance. The cold resistance of the photosystem II reaction centres is higher than the photosynthetic CO2 fixation process. Optimum temperature for net photosynthesis was c. 10°C. The lichen grows along water channels where it is frequently inundated and hydrated to maximum water content, although net photosynthesis is strongly depressed by super saturation. In these habitats the lichen is photosynthetically active for long periods of time. Xanthoria mawsonii also grows at sites where it depends entirely on the early spring snow melt and occasional snow fall for moisture. It has an exceptionally short reactivation phase and is able to utilize snow immediately. Recovery of activity by absorbing water vapour from air, though practically possible, seems to be of ecological importance only under snow at subzero temperatures

Photosynthetic responses of three common mosses from continental Antarctica

Predicting the effects of climate change on Antarctic terrestrial vegetation requires a better knowledge of the ecophysiology of common moss species. In this paper we provide a comprehensive matrix for photosynthesis and major environmental parameters for three dominant Antarctic moss species (Bryum subrotundifolium, B. pseudotriquetrum and Ceratodon purpureus). Using locations in southern Victoria Land, (Granite Harbour, 77°S) and northern Victoria Land (Cape Hallett, 72°S) we determined the responses of net photosynthesis and dark respiration to thallus water content, thallus temperature, photosynthetic photon flux densities and CO2 concentration over several summer seasons. The studies also included microclimate recordings at all sites where the research was carried out in field laboratories. Plant temperature was influenced predominantly by the water regime at the site with dry mosses being warmer. Optimal temperatures for net photosynthesis were 13.7°C, 12.0°C and 6.6°C for B. subrotundifolium, B. pseudotriquetrum and C. purpureus, respectively and fall within the known range for Antarctic mosses. Maximal net photosynthesis at 10°C ranked as B. subrotundifolium > B. pseudotriquetrum > C. purpureus. Net photosynthesis was strongly depressed at subzero temperatures but was substantial at 0°C. Net photosynthesis of the mosses was not saturated by light at optimal water content and thallus temperature. Response of net photosynthesis to increase in water content was as expected for mosses although B. subrotundifolium showed a large depression (60%) at the highest hydrations. Net photosynthesis of both B. subrotundifolium and B. pseudotriquetrum showed a large response to increase in CO2 concentration and this rose with increase in temperature; saturation was not reached for B. pseudotriquetrum at 20°C. There was a high level of variability for species at the same sites in different years and between different locations. This was substantial enough to make prediction of the effects of climate change very difficult at the moment

In situ comparison of Daily Photosynthetic Activity Patterns of Saxicolous Lichens and Mosses in Sierra de Guadarrama. Central Spain

11 pages, figures, and tables statistics.Diurnal time courses ofin situ photosynthetic acñvity oflichens and mosses growing on a granitic boulder in Sierra de Guadarrama, central Spain, were measured during five days in October, 1993. A portable chlorophyll fluorometer was used for assessing photosynthetic activity offour lichen and two bryophyte species together with photosynthetic photon flux density (PPFD) incident at the thallus surface and thallus temperature. The quantum efficiency of photosystem 11 (PSII; AF/Fm'), and the apparent electrón transpon rate through PSIl (AF/Fm' X PPFD) were calculated. The weather changed from wet to dry conditions during the period of measurements. Exposure- and species-related differences in the photosynthetic performance were observed. Both moss species, Hedwigia ciliata and Grimmia pulvinata, showed no sign of thallus drying and the photochemical efficiency of both species was mainly controlled by the diel patterns of PPFD. In contras!, water loss was the majar limiting factor for metabolic activity in the lichen species. Exposure- and species-related changes in thallus color indicating water loss occurred as early as on 18 October in Umbilicaria spodochroa and with a 24-hr-delay in Lasallia hispánica and Umbilicaria grísea (19 October). In Lasallia pustulata thallus color changes were visible only on 20 October when dry weather induced severe dehydration in all lichen species. Within the same species, different microhabitat resulted in a different physiological performance depending on water balances as well as on PPFD conditions. The data demónstrate the potential of fie Id measurements of chlorophyll a fluorescence as a non-intrusive tool for the analysis of the in situ photosynthetic performance of poikilohydric organisms without altering rates of water loss and uptake, which are always crucial in the photosynthetic performance of poikilohydric organisms under natural conditions.The authors thank A. Crespo, A. Pintado, F. Sojo, Madrid, and S. Schroeter, Kiel, for companionship in the field. E. Fuertes, Madrid, is thanked for the determinaron of the moss samples. Valuable assistance with the english manuscript was supplied by T. G. A. Oreen, Hamilton, NZ. The Estación Biogeológica del Ventorillo (CSIC) is thanked for logistic support during the field work. Financial support was provided by the Comisión Interministerial de Ciencia y Tecnología (ANT94-0905) and a travel grant to BS by WTZ 035.2 (BMBF).Peer reviewe