J. J. Beukema, w. J. Wolff & J. J. W. M. Brouns Man is changing the biosphere at an ever increasing Netherlands ministery of Housing, Physical Planning rate. Several of these man-made changes are on a and Health (represented by Dr. G. P. Hekstra), chaired worldwide scale, such as the increase in atmospheric by Dr. w. J. Wolff (Research Institute for Nature concentrations of several gases. In particular the Management) and housed by the Netherlands In­ ongoing increase of the concentration of at­ stitute for Sea Research (N. I. O. Z. , represented by Dr. mospheric carbon dioxide, by excessive burning of J. J. Beukema). fossil fuels and forest destruction, is well­ The written versions of the presentations by 23 par­ documented. By the year 2050, CO levels will ticipants have been brought together in these pro­ 2 almost certainly be twice the pre-industrial concen­ ceedings of the Workshop. trations and this is expected to have far-reaching consequences. Direct effects include higher rates of The first paper, by G. P. HEKSTRA, explains how plant production (also in agriculture). Indirect effects trace gases affect UV-B radiation, alkalinity of the might be less favourable: by the intensified sea, rate of photosynthesis, and greenhouse warm­ 'greenhouse process' (to which several other gases ing.

Inhalt

Introduction..- Climatic Changes..- Man's impact on atmosphere and climate: a global threat? Strategies to combat global warming..- Ecological interpretation of climate projections..- Western European regional climate scenarios in a high greenhouse gas world and agricultural impacts..- Elevated Carbon-Dioxide Concentrations..- The primary productivity of Puccinellia maritima and Spartina anglica: a simple predictive model of response to climatic change..- Direct effects of elevated CO2 concentration levels on grass and clover in 'model-ecosystems'..- Effects of atmospheric carbon dioxide enrichment on salt-marsh plants..- Temperature Changes..- The geographic distribution of seaweed species in relation to temperature: present and past..- Expected effects of changing seawater temperatures on the geographic distribution of seaweed species..- Expected biological effects of long-term changes in temperatures on benthic ecosystems in coastal waters around The Netherlands..- Expected effects of changes in winter temperatures on benthic animals living in soft sediments in coastal North Sea areas..- Effects of temperature changes on infaunal circalittoral bivalves, particularly T. tenuis and T. fabula..- Expected efffects of temperature changes on estuarine fish populations..- Sea-Level Rises..- Sea-level changes and tidal-flat characteristics..- Long-term beach and shoreface changes, NW Jutland, Denmark: effects of a change in wind direction..- Climate change, sea level rise and morphological developments in the Dutch Wadden Sea, a marine wetland..- Sea-level rise and coastal sedimentation in central Noord-Holland (The Netherlands) around 5000 BP: a case study of changes in sedimentation dynamics and sediment distribution patterns..- Ecological impact of sea level rise on coastal ecosystems of Mont-Saint-Michel Bay (France)..- Consequences of sea level rise: implications from the Mississippi Delta..- Possible effects of sea level changes on salt-marsh vegetation..- Salt marshes in The Netherlands Wadden Sea: rising high-tide levels and accreation enhancement..- Inshore birds of the soft coasts and sea-level rise..- UV-B Radiation..- Effects of increased solar UV-B radiation on coastal marine ecosystems: an overview..- Expected changes in Dutch coastal vegetation resulting from enhanced levels of solar UV-B..