Éva Hajnal

Stream order-dependent diversity metrics of epilithic diatom assemblages

Diatoms are considered as an appropriate indicator group for ecological status assessment of surface waters. These organisms can be indicative not only of the waterchemical but also of the hydro-morphological characteristics (e.g., stream size, physical habitat diversity) of running waters. In this study, diatom diversity metrics (species number, Shannon diversity, and evenness) from 506 sites in Pannon ecoregion (Hungary) were compared to the Strahler stream order system established with ArcView GIS 3.2. SOM analyses were performed to exclude the effect of nutrients on diversity metrics along the stream orders. Mixed-effects linear models and Tukey’s post hoc test revealed a linear relationships between species number, diversity and stream orders on ecoregion level from first- to eighth-order streams. The species number increases with an average of 8%, and the diversity by 10% per unit increase of the stream order. However, we could not find relationships with evenness. Autotrophic diversity metrics based on diatom species data appear to increase parallel with the stream order while those of heterotrophic metrics (published in the literature) maximize at medium stream orders. We argue that stream order is a relevant typological parameter which can basically determine the diatom diversity metrics, and it is well applicable in biomonitoring.

Application of benthic diatoms to assess efficiency of conservation management: a case study on the example of three reconstructed soda pans, Hungary

The number of shallow soda pans decreased drastically all over the world and their conservation needs to be urgently forced. Due to their unique physical and chemical features, the lack of appropriate management plans has been a worldwide issue. The aim of present paper was to study the efficiency of the applied water management in three Central European reconstructed soda pans based on their benthic diatom communities, physical and chemical parameters in the years 2012 and 2014. The diatom composition and the diversity metrics indicate unequivocally a worse ecological status of Borsodi-dűlő and Nyéki-szállás than it is characteristic for their natural conditions, which is attributable to their irregular water level modifications. The ecological status of the Legény-tó was far from the required because its conductivity was constantly low, diversity was high and the flora was dominated by mainly freshwater diatom species due to the lack of the natural hydrological cycle. However, these pans have significant conservation values; their good ecological status should be completely reached by restoring their natural hydrological and disturbance regimes.

Functional redundancy modifies species–area relationship for freshwater phytoplankton

Abstract Although species–area relationship (SAR) is among the most extensively studied patterns in ecology, studies on aquatic and/or microbial systems are seriously underrepresented in the literature. We tested the algal SAR in lakes, pools and ponds of various sizes (10−2–108 m2) and similar hydromorphological and trophic characteristics using species‐specific data and functional groups. Besides the expectation that species richness increases monotonously with area, we found a right‐skewed hump‐shaped relationship between the area and phytoplankton species richness. Functional richness however did not show such distortion. Differences between the area dependence of species and functional richness indicate that functional redundancy is responsible for the unusual hump‐backed SAR. We demonstrated that the Small Island Effect, which is a characteristic for macroscopic SARs can also be observed for the phytoplankton. Our results imply a so‐called large lake effect, which means that in case of large lakes, wind‐induced mixing acts strongly against the habitat diversity and development of phytoplankton patchiness and finally results in lower phytoplankton species richness in the pelagial. High functional redundancy of the groups that prefer small‐scale heterogeneity of the habitats is responsible for the unusual humpback relationship. The results lead us to conclude that although the mechanisms that regulate the richness of both microbial communities and communities of macroscopic organisms are similar, their importance can be different in micro‐ and macroscales.

Real time control system for industrial waste water management

Nowadays environmental protection is one of the most important problems. Industrial firms are expected to reduce continuously the environmental load, meanwhile enhancing their productivity. In our study a procedure was developed for the management of the waste water of a pharmaceutical process. The parameters of the waste water, which is flowing into the sewerage system, are generally below the permitted threshold value but occasionally exceeded the limit. To improve this situation an on-line measuring equipment set was applied, by which the chemical oxygen demand (later CODcr) can be estimated on the basis of BRIX refractometric method. A mathematical model was developed for the estimation of the CODcr value and its integral, and the standard deviation. Furthermore a real time control module was developed, which tries to adjust the parameters of the waste water to keep it continuously under the threshold value. It works with three collecting tanks and controls the flow of the water into the tanks and afterwards lets down the water into the drain, or suggests the transportation of it for CODcr removal. The equipment was tested for 45 days, and the measured data were used for the simulation of the control module. During the test period it was established, that the volume of the water which needs transport for CODcr removal became less by 50 percent, while no water, the parameters of which were above the threshold value, flowed into the sewerage system.

Cell automaton modelling algorithms: Implementation and testing in GPU systems

The architecture of todays video cards is able to execute up to hundreds of thousands of operation in parallel. This ability creates the possibility to solve computationally intensive tasks with minimal effort. Our research aims to investigate how to use the graphics hardware for general computing ability in biological models. In the development we have used a re-thought, and upgraded successor of the Nvidia G80 architecture, Fermi-GF104 architecture, and the associated CUDA programming environment in C/C++ language environment. After the developer machine and the test environment were complied, a general cellular automaton modelling framework was developed. It is solved partly by parallel algorithm because it calculates on matrix data structure. Several parallel algorithms and data were tested using the system. The speed of program execution was measured and the CGMA (compute to global memory access) ratio was determined. Compared to the performance of the serial execution we experienced an order of magnitude increase.

Intelligent estimation method for demographic effect onto the research and development sector in Hungary

This papers aim is to investigate the demographic effect onto the research and development sector (R&D). The basis of this question is the serious demographic trend in Hungary, which causes to decrease the number of students in high education. From the 2008 top level, till 2012 there was a dramatic 30% reduction and additional near 35% decrease is probable till 2030. The investigation uses the public data of the Central Statistical Office of Hungary and Educational Office of Hungary. These data contain information on demographic data, scientometrics data and financial data. The main method is correlation mining, clustering and estimation with help of Self Organizing Map (SOM). It was found that the number of publications will decrease about 28%±14.7% in the consequences of demographic changes.

Special issues in the development of a large user based web application

The specification of Irisz Web application shows, that the software will suffer from a large user-originated load. While the usage-statistic measuring is necessary, this creates several needs towards the data and Web-service provider. The article discusses the specialities of the system, the constant pressure of timed data-processing, and providing maintenance abilities during active usage.

Multitude number estimation based on species frequency

The mathematical model for the change of species number in phytoplankton from Lake Stechlin was developed in the other our work, where the species was separated rare and frequent ones. In general case both type species can be settled in and extinct from the ecosystems can be transformed from each to other and a complicate (connected) differential equation system used for description could possible to be solved by ecosystems approximation. The results showed this separation into two types seemed to only be artificial, but it also has biological background, as it may reflect a real difference in the reproductive strategy of species. This latter suggested a little modified criterion compared with the earlier for the division, and the model applying for this case showed a real difference both two types, namely the rare species are stable and the frequent ones are dynamically, as well as that there is no transformation between the rare and frequent species defined in this way. A further consequence is that the differential equation system describing the processes has also become to be separated and they will be solvable one by one without approximation.

Species abundance distribution model for real periphyton samples

The recognition of abundance distribution of periphyton species is important both from theoretical ecological aspect, and from the view of the water monitoring practice. The periphyton species showed exponential distribution, but the rare species have an excess above the expected value. The distribution of the rare species can be hardly investigated by classical statistical methods, because the expected value and the standard deviation are in the same order of magnitude. The distribution function was modelled by computer. This software can generate a multitude by the resultant of two different types of distribution functions, and take random samples from it, according to the valid sampling standard. The artificial samples were compared to the real ones by different methods. The distribution of rare species was found to be uniform in the periphyton.