11 research outputs found
Evaluation of climate change scenarios based on aquatic food web modelling
In the years 2004 and 2005 we collected samples of phytoplankton, zooplankton and macroinvertebrates in an artificial small pond in Budapest. We set up a simulation model predicting the abundance of the cyclopoids, Eudiaptomus zachariasi and Ischnura pumilio by considering only temperature as it affects the abundance of population of the previous day. Phytoplankton abundance was
simulated by considering not only temperature, but the abundance of the three mentioned groups. This
discrete-deterministic model could generate similar patterns like the observed one and testing it on
historical data was successful. However, because the model was overpredicting the abundances of
Ischnura pumilio and Cyclopoida at the end of the year, these results were not considered. Running the
model with the data series of climate change scenarios, we had an opportunity to predict the individual
numbers for the period around 2050. If the model is run with the data series of the two scenarios UKHI
and UKLO, which predict drastic global warming, then we can observe a decrease in abundance and shift
in the date of the maximum abundance occurring (excluding Ischnura pumilio, where the maximum
abundance increases and it occurs later), whereas under unchanged climatic conditions (BASE scenario)
the change in abundance is negligible. According to the scenarios GFDL 2535, GFDL 5564 and UKTR, a
transition could be noticed
Trends in research on the possible effects of climate change concerning aquatic ecosystems with special emphasis on the modelling approach
Knowledge on the expected effects of climate change on aquatic ecosystems is defined by three
ways. On the one hand, long-term observation in the field serves as a basis for the possible changes; on
the other hand, the experimental approach may bring valuable pieces of information to the research field.
The expected effects of climate change cannot be studied by empirical approach; rather mathematical
models are useful tools for this purpose. Within this study, the main findings of field observations and
their implications for future were summarized; moreover, the modelling approaches were discussed in a
more detailed way. Some models try to describe the variation of physical parameters in a given aquatic
habitat, thus our knowledge on their biota is confined to the findings based on our present observations.
Others are destined for answering special issues related to the given water body. Complex ecosystem
models are the keys of our better understanding of the possible effects of climate change. Basically, these
models were not created for testing the influence of global warming, rather focused on the description of
a complex system (e. g. a lake) involving environmental variables, nutrients. However, such models are
capable of studying climatic changes as well by taking into consideration a large set of environmental
variables. Mostly, the outputs are consistent with the assumptions based on the findings in the field. Since
synthetized models are rather difficult to handle and require quite large series of data, the authors
proposed a more simple modelling approach, which is capable of examining the effects of global
warming. This approach includes weather dependent simulation modelling of the seasonal dynamics of
aquatic organisms within a simplified framework
Long-term dynamic patterns and diversity of phytoplankton communities in a large eutrophic river (the case of River Danube, Hungary)
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 GĂśd, 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
Analysis of climate change scenarios based on modelling of the seasonal dynamics of a Danubian copepod species
Climate change is one of the most crucial ecological problems of our age with great influence.
Seasonal dynamics of aquatic communities are â among others â 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 Danubeâs GĂśd 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 GĂśd region which are
mostly similar to the future climate of the GĂśd 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 21st century, and the way the seasonal
dynamics of a chosen planktonic crustacean species may follow this change. According to our results the
area of GĂśd 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
Comparative Assessment of Climate Change Scenarios Based on Aquatic Food Web Modeling
In the years 2004 and 2005, we collected samples of phytoplankton, zooplankton, and macroinvertebrates in an artificial small pond in Budapest (Hungary). We set up a simulation model predicting the abundances of the cyclopoids, Eudiaptomus zachariasi, and Ischnura pumilio by considering only temperature and the abundance of population of the previous day. Phytoplankton abundance was simulated by considering not only temperature but the abundances of the three mentioned groups. When we ran the model with the data series of internationally accepted climate change scenarios, the different outcomes were discussed. Comparative assessment of the alternative climate change scenarios was also carried out with statistical methods
Effects of TemperatureâClimate Patterns on the Production of Some Competitive Species on Grounds of Modelling
Climate change has serious effects on the setting
up and the operation of natural ecosystems. Small increase
in temperature could cause rise in the amount of some
species or potential disappearance of others. During our
researches, the dispersion of the species and biomass
production of a theoretical ecosystem were examined on
the effect of the temperatureâclimate change. The answers
of the ecosystems which are given to the climate change
could be described by means of global climate modelling
and dynamic vegetation models. The examination of the
operation of the ecosystems is only possible in huge centres
on supercomputers because of the number and the
complexity of the calculation. The number of the calculation
could be decreased to the level of a PC by considering
the temperature and the reproduction during modelling a
theoretical ecosystem, and several important theoretical
questions could be answered
Climate change and freshwater zooplankton: what does it boil down to?
Recently, major advances in the climateâzooplankton 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
Challenges and opportunities for integrating lake ecosystem modelling approaches
A large number and wide variety of lake ecosystem models have been developed and published during the past four decades. We identify two challenges for making further progress in this field. One such challenge is to avoid developing more models largely following the concept of others (âreinventing the wheelâ). The other challenge is to avoid focusing on only one type of model, while ignoring new and diverse approaches that have become available (âhaving tunnel visionâ). In this paper, we aim at improving the awareness of existing models and knowledge of concurrent approaches in lake ecosystem modelling, without covering all possible model tools and avenues. First, we present a broad variety of modelling approaches. To illustrate these approaches, we give brief descriptions of rather arbitrarily selected sets of specific models. We deal with static models (steady state and regression models), complex dynamic models (CAEDYM, CE-QUAL-W2, Delft 3D-ECO, LakeMab, LakeWeb, MyLake, PCLake, PROTECH, SALMO), structurally dynamic models and minimal dynamic models. We also discuss a group of approaches that could all be classified as individual based: super-individual models (Piscator, Charisma), physiologically structured models, stage-structured models and trait-based models. We briefly mention genetic algorithms, neural networks, Kalman filters and fuzzy logic. Thereafter, we zoom in, as an in-depth example, on the multi-decadal development and application of the lake ecosystem model PCLake and related models (PCLake Metamodel, Lake Shira Model, IPH-TRIM3D-PCLake). In the discussion, we argue that while the historical development of each approach and model is understandable given its âleading principleâ, there are many opportunities for combining approaches. We take the point of view that a single ârightâ approach does not exist and should not be strived for. Instead, multiple modelling approaches, applied concurrently to a given problem, can help develop an integrative view on the functioning of lake ecosystems. We end with a set of specific recommendations that may be of help in the further development of lake ecosystem model