Objetivo
The overall objective of this project is firstly to assess the influence of increased UV radiation and temperature on photosynthesis, the uptake of major nutrients and primary production of macrophytes and, secondly, to determine the existence and the nature of strategies against potential UV damage in marine macrophytes of different climatic regions with different levels of UV radiation. The studies will allow predictions of changes in the composition of the benthic vegetation in the different climatic regions.
Apart from phytoplankton, macroalgae and seagrasses (macrophytes) play an important role in primary production in coastal waters serving as food for herbivores and detritivores and as shelter for juvenile animals. Marine macrophytes may be highly vulnerable by UV radiation, as they become exposed to full sunlight at low tide. Moreover, macrophytes are more affected by UV radiation in clear waters than in turbid waters since the penetration of UV is higher. This may have deleterious effects especially in polar species, where seasonal growth activity coincides with high water transparencies and high UV radiation in spring. Consequently the capacity of carbon assimilation and carbon sinking by macrophytes is expected to be reduced especially in clear waters, which is also important with regard to diminishing atmospheric CO2 increase (greenhouse effect). Neither is known how UV influences the uptake of nutrients by macrophytes and, hence, the primary productivity of individual species. The same applies to the interactive effects of UV radiation and temperature in their effect on photosynthesis, growth and reproduction. All these abiotic key factors clearly effect interspecific competition and eventually the community structure of the macrophytic vegetation. A possible injury of coastal aquatic ecosystems by global climate changes will certainly cause a decrease of local fisheries and of aquaculture.
The project methodology will combine field observations, field and laboratory experiments and modelling work in order to assess consequences of global climatic changes on the investigated coastal ecosystems situated along a latitudinal gradient form the warm-temperate region (Malaga, Cadiz), through the cold temperate region (Helgoland) to the Arctic region (Spitsbergen).
The specific objectives include (a) measurements of abiotic factors, especially photosynthetic active and UV radiation, temperature and nutrient levels and their daily and seasonal variations in the various regions, (b) an assessment of community structures in the different littoral systems in relation to biooptical characteristics, (c) transplantation and UV exclusion experiments in order to assess the responses of individual species to UV radiation from the viewpoint of occupied niches, (c) studies on the influence of UV radiation on growth, photosynthesis and nutrient uptake of eu- and sublittoral macrophytes for the various regions in the field and in the laboratory. (e) Further on the prevention of UV damage in selected macroalgae from the different regions by dynamic photoinhibition, production of screening pigments and quenching of cytotoxic intermediates and (f) the effectiveness of damage repair mechanisms will be studied in the laboratory and the field. The laboratory work will include studies about the combined effects of temperature and UV radiation. (g) A major task of the project will be to combine the results coming out of the various studies given above in order to achieve the required insight into the changes of the investigated coastal ecosystems induced by global climate changes due to atmospheric ozone degraphic distribution of individual species and of community structure will be predicted by integration of the results obtained in the various field and laboratory experiments outline above.
Ámbito científico
- natural sciencesbiological sciencesmarine biology
- natural sciencesearth and related environmental scienceshydrologylimnology
- natural sciencesearth and related environmental sciencesatmospheric sciencesclimatologyclimatic changes
- natural sciencesbiological sciencesbotany
- natural sciencesbiological sciencesecologyecosystemscoastal ecosystems