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.

Effect of sampling effort and sampling frequency on the composition of the planktonic crustacean assemblage: a case study of the river Danube

Although numerous studies have focused on the seasonal dynamics of riverine zooplankton, little is known about its short-term variation. In order to examine the effects of sampling frequency and sampling effort, microcrustacean samples were collected at daily intervals between 13 June and 21 July of 2007 in a parapotamal side arm of the river Danube, Hungary. Samples were also taken at biweekly intervals from November 2006 to May 2008. After presenting the community dynamics, the effect of sampling effort was evaluated with two different methods; the minimal sample size was also estimated. We introduced a single index (potential dynamic information loss; to determine the potential loss of information when sampling frequency is reduced. The formula was calculated for the total abundance, densities of the dominant taxa, adult/larva ratios of copepods and for two different diversity measures. Results suggest that abundances may experience notable fluctuations even within 1 week, as do diversities and adult/larva ratios.

A családi fészekben élő fiatal felnőttek és fogyasztói döntéseik (In the family nest living young adults and their consumer decisions)

Fiatal felnőttek nagyarányú jelenléte a szülői háztartásokban nemcsak Magyarországon és Európában jellemző, de a fejlett ipari országokban általánosan megfigyelhető jelenség. Az Európai Unióban élő 18–34 év közötti fiatalok 46%-a él együtt legalább egyik szülőjével, a magyar fiatalok esetében hasonló az arány. A fiatalok kitolódó felnőtté válása azt is jelenti, hogy a szülők egyre későbbi időponttól kezdve rendelkeznek szabadabban idejükkel és anyagi forrásaikkal, a fiatal felnőttek döntései pedig részben szüleik részvételével történik. Jelen cikk arra keresi a választ, hogy a szülői fészekben élő vagy a szüleiktől részben függő fiatalok milyen döntési mintákkal rendelkeznek, illetve vásárlási döntéseikben mennyire önállóak. A kérdés vizsgálatát a szülői háztól függő egyetemista fiatalok körében végzett kérdőíves megkérdezés segítségével a szerzők elemezték, és arra is lehetőségük volt, hogy a családtagok által írt rövid esszék segítségével a kérdést több oldalról vizsgálják meg. Eredményeik szerint a szülői háztól függő fiatal felnőttek önálló döntésre képes, sok esetben szakértő fogyasztók, döntéseik önállóságát azonban a termékkategória, a családdal való kapcsolattartás gyakorisága, a családforma és a nemi szerepek is befolyásolják. ____ High ratio of adult children is still living in their parents’ home. This is a significant phenomenon that can be observed in Hungary and throughout Europe, while influences living trends globally. In the EU, 46% of youth between 18-34 years live with at least one of their parents and this same statistic holds true in the case of Hungary. This postponement of adulthood allows parents to enjoy more free time and have higher disposable income from later in life. The young adults, however, in the household make their consumer decisions under parental control. The purpose of this study is to explore the decisionmaking styles of young adults and their independence from their parents in shopping-related decision-making through a literature review and primary study. The survey focused on university students who are dependent on their parental home and short essays were also collected from family members of the target group in order to gain a more complex view on this phenomenon. According to the results the following conclusion can be made: young adults living in their parents’ home are competent consumers with individual decisions, in addition, they are consumer experts within the family in many cases. However, their independent shopping-related decision-making is influenced by product category, frequency of connection to the family home, family form and also sex role orientations.