Recently, major advances in the climatezooplankton interface have been made some of which appeared to receive much attention in a broader audience of ecologists as well. In contrast to the marine realm, however, we still lack a more holistic summary of recent knowledge in freshwater. We discuss climate change-related variation in physical and biological attributes of lakes and running waters, high-order ecological functions, and subsequent alteration in zooplankton abundance, phenology, distribution, body size, community structure, life history parameters, and behavior by focusing on community level responses. The adequacy of large-scale climatic indices in ecology has received considerable support and provided a framework for the interpretation of community and species level responses in freshwater zooplankton. Modeling perspectives deserve particular consideration, since this promising stream of ecology is of particular applicability in climate change research owing to the inherently predictive nature of this field. In the future, ecologists should expand their research on species beyond daphnids, should address questions as to how different intrinsic and extrinsic drivers interact, should move beyond correlative approaches toward more mechanistic explanations, and last but not least, should facilitate transfer of biological data both across space and time.

The aim of this study was to reveal the spatial and temporal variation in biomass, density, and size structure of the invasive clam, Corbicula fluminea in the Danube River catchment and to explore the environmental factors determining these patterns. Samples were taken seasonally during the years 2007 and 2008 at 15 sites located along a river continuum from a second order stream to the Danube River. C. fluminea was the most abundant species in the main arm of the Danube; however, it was found in great density in the side arms, too. In the Ipoly River it only occured close to the conjuction, and it was not present at all in the second and third order streams. Regression models were developed to predict dry mass (DW, g) from linear body dimension [shell length (L), mm]. For the description of length-dry mass relationship, the power function (DW = a * L b ) was applied. The highest density, biomass, and mean shell length were 178 ind. m −2 , 24.9697 g DW m −2 , and 21.99 mm, respectively. ANOVA detected significant spatial variation in biomass; however, significant temporal variation was not recorded between the years, only among the seasons. Multiple linear regressions were used to find the relationship between the biomass and the environmental parameters. The coarse and very fine sediment fractions and the high water temperature provided suitable habitat for C. fluminea. Although statistically significant correlation was not detected between the chlorophyll-a content of water and the biomass, the highest biomass values were recorded at sites with high chlorophyll-a value.

Verasztó et al.: Long-term dynamic patterns and diversity of phytoplankton communities in a large eutrophic river - Abstract. In this paper we present the composition, seasonal dynamics and fluctuations in diversity of the phytoplankton in the Danube River over 24 years. Weekly samplings were conducted at one section of the river at Göd, in the 1669 river kilometer segment. The change in the phytoplankton community structure was analyzed in relation of water temperature and discharge means. Our findings support the opinion that the Danube is very rich in species, although many of the species are rare and could be described only as coloring species. Results indicate trends in the phytoplankton abundance, which are only detectable in long-term studies. By the help of diversity indices we have observed an increase in the phytoplankton community diversity. With the relevant information, an explanation of the significant changes in diversity and richness was formed. Our goals were a construction of a solid database of the phytoplankton, examining the seasonal dynamics of the phytoplankton through a 24 year long study and to see the most important changing factors of the community. The results of this study are to assist and help future model developments to predict the phytoplankton seasonal dynamic patterns.

Ecological models have often been used in order to answer questions that are in the limelight of recent researches such as the possible effects of climate change. The methodology of tactical models is a very useful tool comparison to those complex models requiring relatively large set of input parameters. In this study, a theoretical strategic model (TEGM ) was adapted to the field data on the basis of a 24-year long monitoring database of phytoplankton in the Danube River at the station of Göd, Hungary (at 1669 river kilometer -hereafter referred to as "rkm"). The Danubian Phytoplankton Growth Model (DPGM) is able to describe the seasonal dynamics of phytoplankton biomass (mg L −1 ) based on daily temperature, but takes the availability of light into consideration as well. In order to improve fitting, the 24-year long database was split in two parts in accordance with environmental sustainability. The period of 1979-1990 has a higher level of nutrient excess compared with that of the 1991-2002. The authors assume that, in the above-mentioned periods, phytoplankton responded to temperature in two different ways, thus two submodels were developed, DPGM-sA and DPGMsB. Observed and simulated data correlated quite well. Findings suggest that linear temperature rise brings drastic change to phytoplankton only in case of high nutrient load and it is mostly realized through the increase of yearly total biomass.

ANALYSIS OF CLIMATE CHANGE SCENARIOS BASED ON MODELLING OF THE SEASONAL DYNAMICS OF A DANUBIAN COPEPOD SPECIESAbstract. Climate change is one of the most crucial ecological problems of our age with great influence. Seasonal dynamics of aquatic communities are -among others -regulated by the climate, especially by temperature. In this case study we attempted the simulation modelling of the seasonal dynamics of a copepod species, Cyclops vicinus, which ranks among the zooplankton community, based on a quantitative database containing ten years of data from the Danube's Göd area. We set up a simulation model predicting the abundance of Cyclops vicinus by considering only temperature as it affects the abundance of population. The model was adapted to eight years of daily temperature data observed between 1981 and 1994 and was tested successfully with the additional data of two further years. The model was run with the data series of climate change scenarios specified for the period around 2070-2100. On the other hand we looked for the geographically analogous areas with the Göd region which are mostly similar to the future climate of the Göd area. By means of the above-mentioned points we can get a view how the climate of the region will change by the end of the 21 st century, and the way the seasonal dynamics of a chosen planktonic crustacean species may follow this change. According to our results the area of Göd will be similar to the northern region of Greece. The maximum abundance of the examined species occurs a month to one and a half months earlier, moreover larger variances are expected between years in respect of the abundance. The deviations are expected in the direction of smaller or significantly larger abundance not observed earlier. One possible approach is the weather conditions depending simulation modelling of an appropriately chosen aquatic community. By the help of the simulation models we can predict the possible changes in the seasonal dynamics of the given aquatic community in the case of the alternative climate change scenarios, it is indeterminate though. Considering the errors and assumptions of the model, the most likely, possible scenarios of the effect of climate change can be achieved (Hufnagel and Gaál, 2005). For the modelling of the seasonal dynamics of population-collectives applying of extant model system is possible (Ladányi et al. 2003). Keywords: Cyclops vicinus, geographical analogy, hydrobiology, simulation modellingSipkay et al.: Analysis of climate change scenarios based on modelling of the seasonal dynamics of a Danubian copepod species -102The seasonal dynamics of freshwater zooplankton communities is primarily influenced by climatic factors. Several authors have tried to describe and explore these connections (Bernot et al. 2004, Zelikman and Kamshilov, 1960, Hassel 1986, Villate et al. 1997. For modelling the seasonal dynamics complex approach is used generally: besides environmental factors, predator and prey terms are used as parameters (Broekhuizen et al. 1995, Angeli...

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