Albert Tóth

Effect of sports fisherman activities on dragonfly assemblages on a Hungarian river floodplain.

We studied the dragonfly fauna along a 15 km stretch of thefloodplain of the regulated, first-order river Tisza, Hungary. Data on capturedand observed adults, larvae and exuvia were recorded. Observations were madefrom May to October 1998 and 1999 on 34 species, which is 52% of theHungarian fauna. Classification on the basis of faunistic similarity revealedthat habitat-level differences, associated with various degrees of physicalanthropogenic impact on bank vegetation, can exceed variation among the waterbodies of different types (backwater, pond, marsh, canal, river). The richestsites were dominated by structurally diverse macrophyte vegetation, while flowing waters (river and canal) were poorest in species. Odonata were found tobe reliable indicators of small-scale habitat patterns, reflecting vegetationdifferences even within single water bodies where the sampling spots werearranged just a few hundred metres apart. Along a gradient of utilisationintensity, the species number of Odonata assemblages and the summed relativeabundance of the five rarest species of the study area decreased linearly withincreasing fragmentation of the marginal vegetation. Sports fishermanactivities, implying disruption of the littoral marsh zone by establishment ofclearings and excessive trampling of the banks, can also be monitored bydragonfly faunistic investigations. Our results demonstrate that conservation ofthese varied floodplain water bodies requires the control of sports fishingactivity, suggesting that (i) to maintain the representative odonate fauna ofthe water bodies, some non-fragmented shores must be provided; and (ii) permanentfishing stands should not exceed 8 m mean width and should beseparated by at least 12 m of intact riparian sections.

Emergence patterns of riverine dragonflies (Odonata: Gomphidae) in Hungary: variations between habitats and years

In this paper the results of a six-year study on riverine dragonflies (Odonata: Gomphidae) emergence based on the systematic collection of exuviae are presented. The exuviae were counted to determine variations in species composition, abundance and emergence pattern of gomphids at four different sites along the rivers Tisza and Szamos, as well as at a selected site in five different years. While the number of species decreased, the abundance of exuviae increased downstream the river Tisza. The total numbers of exuviae differed significantly between the dammed and non-dammed sites. The emergence of gomphids varied in initiation, synchronisation and also in duration between sites as well as between years. The onset of emergence was dependent mainly on the species-specific temperature sums, consequently earlier or later emergence resulted from the differences in the spring water temperature. The duration of emergence in G. flavipes and G. vulgatissimus was twice as long at the dammed site, characterised by a higher larval density, as at the other sites. In the degree of synchrony G. flavipes showed the emergence characteristics both of the spring and the summer species. Such interyear variations at the same site might have been attributed to the differences in annual fluctuations in the water temperature, indicating that rising temperatures may influence not only the onset of emergence but the synchrony as well.

Element composition of Rosa canina and Rubus fruticosus fruits at an abandoned metalliferous minesite in N-Hungary

One of the biggest challenges for the safe maize production is the yield stability in a wide range of environments with different soil fertility, weather conditions, prevailing pests and diseases as well as cultural practices. In order to achieve it, new hybrids with higher tolerance to biotic and abiotic stress are continuously being created. In order to compare performance of maize hybrids in environments with different levels and types of stress, and relate it to the stalk lodging incidence, we compared performance of 64 maize hybrids obtained by crossing 16 inbred lines with four inbred testers in three different environments. Two environments at same location (Rugvica) differed in crop rotation, and the third environment at location Botinec was considered as dry because of low water capacity of the soil. Mixed models that included all design elements and genetic background of hybrids were used to analyze the effect of lodging on yield in different environments. The results show that stalk lodging had a significant effect on yield, but significant lodging x environment interaction indicates that this effect was rather environment specific.Sweet pepper Istra F1 hybrid was grown in a greenhouse on K rich soil. For evaluation of K antagonism, two K rates (55 and 85 kg ha-1) were applied in a randomized complete block design with four replications. Total number of fruits, total number of BER affected fruits as well as average fruit mass were recorded for each harvest. Fruit and leaf K and Ca content were determined at three plant growth stages (at the stage of the first, third and fifth fruit cluster). Higher K rate gave higher : average fruit mass (169.45 g), total number of fruits per plant (7.95), number of BER affected fruits per plant (3.82), K in leaves (5.44% DM), K in fruits (6.35% DM), but negatively correlated with Ca concentration in fruits (0.57% DM) and leaves (3.24% DM). This resulted in decreased marketable yield of sweet pepper fruits.

Seasonal succession of phytoplankton in a small oligotrophic oxbow and some consideration to the PEG model

Most of the research on the structure and dynamics of phytoplankton in lacustrine environments was performed in larger lakes. In small lakes, especially oxbows in which there is a profusion of waterbodies, available information is scarce (REYNOLDS 1993). Phytoplankton seasonal succession is discussed by comparison with the world model for lakes, PEG (Plankton Ecology Group, SoMMER et al. 1986). This model consists of 24 sequential statements, which describe, step by step, the seasonal events, which occur in phytoplankton and zooplankton of an idealised standard lake (Lake Constance). These statements have been tested using data from 24 different lakes, none of which were oxbows. The objectives of this paper are to describe the phytoplankton structure and to discuss the main patterns of seasonal variations of the phytoplankton species of a Hungarian oxbow. The present article is the first concerning an oxbow phytoplankton community and discusses data in relation to the steps proposed by the PEG model

Theory of phytoremediation and its Hungarian practice

Oil rape is a valuable fodder because in early spring and late autumn it produces green forage used for the nutrition of domestic animals. It has been replacing sunflower and soy in colder and wetter regions. It is additionally advantageous because it leaves behind more nitrogen in soil, which is beneficial to other plants in plant rotation. There are some possible ways for the fixation of nitrogen in soil and they are as follows: by the means of oil rape straw ; by relatively long roots ; by the action of nitrogen bacteria, which perform the nitrogen synthesis within their root system, which is the case in some leguminous plants. Oil seed rape is expected to be wider used in crop rotation of West and Middle Europe, Croatia included. Due to this various sorts have been introduced and potential positive impacts have been studied in order to boost the process. This paper presents information on barley and wheat yield in case when they were sown after oil seed rape and corn. The aim of the research is to determine the presence of positive impacts upon the soil with special attention paid to a potential increase of nitrogen content after oil seed rape was grown. The preceding crops had statistically significant effect. Rape yield was significantly higher compared to the one with corn as preceding crops. Very similar results were obtained in 2007.The maize hybrids seed from three different FAO groups (FAO 400, FAO 500 and FAO 600) in four fractions (KO, KP, SO and SP) produced in two climatically different years (extremely dry 2000 and extremely wet 2001) had been different in quality and chemical composition. The effects of year, genetic specifity and seed fraction at the kernel mass, chemical composition (starch, proteins, cellulose, oil and moisture content) and seed vigour have been evaluated. The influence of agroecological conditions during two production years have been exposed at seed chemical composition and vigour indicators (cold test – CT and bulk seed electrical conductivity - EC). The genetic specificity and seed fraction had significant influence at all tested indices, with the exception of the influence of the fraction at the starch content

Morphology of bitter sweet (Solanum dulcamara L.) in contrasting marsh habitats

Summary In this paper we studied the morphology of bitter sweet (Solanum dulcamara L.) in four casting marsh habitats to assess the degree of intraspecific variation in above-ground vegetative features. Mean leaf area, total leaf mass, and stem weight were shown to reflect habitat impact rather than plant age and can thus be proposed for subtle habitat characterisation. Variation in mean leaf area among populations was found to exceed that within population suggesting local differentiation. In overall morphology three distinct types were established. These represent different growth habits which appear to be determined primarily by the physiognomy of the host plant assemblage. These results necessitate further explanations by following investigations, especially those to evaluate the degree of genotypical fixation of the morphological differences observed in Solanum dulcamara.

Ramet distribution, leaf morphometry and elemental composition of Caltha palustris L. along a water depth gradient

Summary Ramet distribution, leaf morphometry and elemental composition of Caltha palustris L. were studied along a hydrologic gradient in Nyarias marsh, N. E. Hungary, to identify patterns associated with water depth. Water-table height was linearly correlated with distance over most of the plants distribution range. Caltha ramets were not dispersed uniformly but appeared in an aggregated pattern of a 12m scale. However, no clear relationship was found between water depth and the density of ramets, leaf number per ramet, aspects of plant performance (leaf blade and petiole dry weight), water status (water content of leaf parts), or leaf morphometry (lamina length and breadth, petiole length). Leaf size decreased towards both ends of the transect, and was highest at intermediate position. Contrastingly, foliar concentrations of several elements (e.g. Na, Mn, Cu) and especially the Fe: Mn ratio were strongly correlated with water-table height. Principal components analysis revealed two groups of elements: one discriminating between the lamina and the petiole but uncorrelated with the gradient (Ca, S, Fe, P, AI, K), and another not discriminating but positively correlated with the gradient (Na, Mn, Mg). The complex patterns of Caltha population traits in Nyarias demonstrate the ecologic importance of small-scale spatial (i.e. microtopographic) differences in wetlands. Besides water depth and duration per se, biotic factors such as gradients of standing crop, species richness or competition intensity may have intricate effects on single populations. Foliar Fe: Mn ratios, however, seem to be directly determined by water-table height and associated soil chemistry, thus can be a subtile indicator of wetland water conditions.

Characteristic features of tropical fry culture, from the point of view of applied limnology

Today most fish stocks in natural waters are, to some extent, under human control (RICKER 1975, EDWARDS & MEGREY 1989). Thus, the importance of fish farming, including the recruitment of natural stock, is growing. In Brazilian fish culture the production of post-larvae and fry using efficient methods of artificial propagation (WoYNÁROVICH & HoRVATH 1989) are of major concern. Our studies were carried out in Northeast Brazil (Nordeste), the least developed region of the country, where fish farming is very important for feeding the local population. The study site, a fish farm along the lower reach of the river São Francisco valley, some 60 km off the Atlantic, is characterized by a climate that is transitional between the tropical semi-arid and tropicallittoral rypes. This implies the regular alternation of wet and dry seasons. The most important aspect of this climate is a constant, high water temperature (in the fry culture ponds at a depth of l m, depending on transparency, temperature varied between 24 and 26 oe during the wet and between 26 and 30 oe during the dry season). Another important feature of the river is its oligotrophic state with apparently impoverished phytoand zooplankton populations. The fish fauna of the river São Francisco valley has been described by BRITSKI et al. (1986) and SATO et al. (1987). A general overview of the feeding behaviour of fish assemblages in Brazilian rivers and reservoirs has been presented by ARAUJO-LIMA et al. (1995). Other important contributions regarding the zooplankton biomass, productivity, composition and temporal patterns in reservoirs and naturallakes in tropical Brazil include ARciFA et al. (1992) and RocHA et al. (1995). The zooplankton in the river São Francisco itself has been studied in detail by NEUMANN-LEITAo & NoGUEIRA-PARANHos (1989), while fish-zooplankton interactions have been investigated by ZARET (1984). We studied the farming of three species. Tropical culture, in particular nutritional requirements, of the common carp (Cyprinus carpio) has been described by HORVATH & PÉKH (1984) and WOYNÁROVICH & HORVATH (1989). Some aspects of the feeding characteristics of curimata (Prochilodus marggravit) in natural waters have been studied by SAZIMA & eARAMASCHI (1989), and the experience in fish culture has been summarized by PAIXAo & HANCZ (1989) and NAGY (1990). The feeding characteristics of tambaqui ( Colossoma macropomum) under natural growing conditions have been presented by HONDA (1974) and GouLDING & eARvALHO (1982), and in fish culture by WOYNÁROVICH (1986), PINHEIRO & SILVA (1998).

Importance of the metaphytic life form in wetlands: an improved sampling technique

Although many different types and definitions exist, a common feature of wetlands is an abundant, specialized vegetation (GoPAL 1990, MmcH 1996). Extensive beds o f macrophytes ( covering u p to 90% of the total water surface) are generally present in shallow, stagnant inland waters, where they mark the magnitude of the littoral zone (PIECZYNSKA 1990). To provide a representative evaluation of the biota in these extremely variable water types, most samples should be taken from vegetated parts of the water bodies. Typically, macrophyte stands are rich in fastmoving and/or well-hiding macroscopic organisms (e.g. ANoRIKOVICS 1975) which are rather difficult to sample even for relatively simple faunistic surveys.