Mária Dinka

The effect of mineral nutrient enrichment of lake Balaton on the common reed (Phragmites australis)

On the north shore of Lake Balaton four study areas were selected with different levels of mineral nutrient supply (two of them are at sewage inflows, one is at the mouth of a natural watercourse, and one is unaffected by water inflow).Studies were made on the development ofPhragmites australis(Cav.) Trin. exSteudel stands. Monthly levels of N, P, K, Na, Ca and Mg in the organs (leaf-blade, leaf-sheath, culm, aquatic root, rhizome and root) of reed were determined from April to October in 1980. Differences were detected between the four study areas in the shoot height, mass, growth rate and element contents.In the aboveground organs, the levels of N, P, and K showed a decrease all through the growing season, but Ca and Mg rose to a peak before declining for the rest of the season. In the underground organs the levels of N and P decreased to a minimum in June to July and thereafter the quantities of these elements gradually increased. In the most heavily contaminated area (area IV), significantly higher levels of tissue N, P and K were found.

Influence of water level fluctuation on the spatial dynamic of the water chemistry at Lake Fertõ/Neusiedler See

Abstract Lake Ferto/Neusiedler See is a steppe lake situated on the Hungarian-Austrian border with a surface area of 309 km 2 . It is an extremely shallow lake with regulated outflow. 54% of the whole lake and 85% of the Hungarian part (75 km 2 ) is covered by reed. There are numerous reedless areas (inner ponds) of variable size within the reed belt, which is enmeshed with canals connecting the inner ponds with the open water areas. Fundamental differences were recorded in the water chemistry of the three water type areas, open water, canals and inner ponds. The degree of these differences is basically determined by the distance from the open water areas and the water level of the actual years. An extremely high, an average and an extremely low water level year was examined, in order to present the spatial and temporal differences in the water chemistry of the investigated water bodies. Differences due to the water level fluctuation between years in the three different water types are discussed on the basis of electrical conductivity, cation, and anion concentration changes of the water. Our results support the concept of high instability of Lake Ferto and describe habitats with remarkable temporal and spatial variability. The high influence of water level on habitat conditions at different sites of the lake recommend a carefull water level regulation strategy.

Carbohydrate and nutrient content in rhizomes of Phragmites australis from different habitats of Lake FertÕ/Neusiedlersee

Abstract Changes in the soluble sugar, starch, total non-structural carbohydrate (TNC) and nutrient (N, P, K) concentration in the reed rhizome were investigated in different reed habitat types in Lake Ferto/Neusiedlersee during the vegetation period in 1993 to 94. Three die-back and four vigorous reed stands were monitored. For biomass estimations rhizomes were collected twice, in early summer and in autumn. They were calculated to be 1.9 to 2.7 kg/m 2 at die-back and 3.1 to 6.1 kg/m 2 at vigorous sites. The carbohydrate and nutrient concentrations of the reed rhizomes were high at the beginning of the vegetation period; they reached their minima in May–June, which was followed by a gradual increase until the end of the vegetation period. From autumn to spring the concentrations decreased, e.g. TNC concentration by 15 to 40% at vigorous, 50 to 70% at die-back sites. In both years the lowest carbohydrate concentrations were recorded at the end of May, a month before the inflorescence developed (vigorous sites: 50–70 mg TNC/g, die-back sites: 70–120 mg TNC/g). In that period the standing stock of the TNC in the rhizome did not separate the sites clearly, and the smallest carbohydrate standing stock was measured at a vigorous site with a high water cover. At the beginning of summer and in autumn the soluble sugar, TNC and N concentration values were higher at the die-back than at the vigorous sites but the standing stock was higher at the vigorous sites. In autumn the TNC standing stock of the rhizomes was between 780 and 1200 g/m 2 at vigorous, between 380 and 690 g/m 2 at die-back sites. This is especially important for the reactions and resistance of die-back reed stands to unfavourable conditions.

Decomposition of Typha angustifolia and Phragmites australis in the littoral zone of a shallow lake

Decomposition of air-dried live Typha angustifolia (L) stems and leaves and Phragmites australis (Cav. Trin ex Steud.) leaves and culms were studied in a shallow freshwater lake (Lake Fehér, Fertő-Hanság National Park, Hungary) using the litter bag technique. Samples were analyzed for dry mass, fiber (cellulose, hemicelluloses, lignin) and nutrient (C, N, P, S) contents, litter-associated fungal biomass (ergosterol concentration), potential microbial respiration (electron transport activity: ETS) and cellulolytic bacteria. In terms of mesh size, there were no significant differences in the examined parameters of P. australis leaves and culms and T. angustifolia stems with leaves. P. australis leaves had the highest rate of decomposition and P. australis culms the lowest. Hemicellulose degraded more rapidly than the other fibers, while the lignin had the slowest rate of decomposition.The ETS activity of the examined plant litter types increased from day 91st to 237th while decomposition processes were most active, ergosterol contents were high, and there were few cellulolytic bacteria. The counts of cellulolytic bacteria fluctuated during the decomposition period, they were high at the beginning then they decreased. In each case bacteria were found to be the first colonizers of plant detritus, and were followed by fungal growth.

Some characteristics of reed (Phragmites australis/Cav./Trin ex Steudel) that indicate different health between vigorous and die-back stands

The widespread degradation ofEuropean reed stands is eaused by complex faetors and needs a multifold researeh strategy. Several studies have deseribed the different conditions at vigorous and die-baek si tes of the same lakes and the response of the reed stands to these differenees (KLóTZLI 1973, RAGHI-ATRI & BORNKAMM 1979, DINKA 1986, ÜSTENDORP 1989, KovAcs 1990, KüHL & KoHL 1992). The eoordinated investigations of the EUREED programme also produeed many results in this field (REEDNEWS 1995, ARMSTRONG et al. 1996, van der PUTTEN 1997, SoRRELL et al. 1997). In the present study, firsdy morphologieal differenees of reeds becween vigorous and die-baek sites and the strueture of the reed stands are deseribed. Seeondly, growth parameters that demonstrate the most marked differenees in growth between vigorous and die-baek stands are diseussed.

Variations in leaf pigment content and photosynthetic activity of Phragmites australis in healthy and die-back reed stands of Lake Ferto/Neusiedlersee

The photosynthetic capacity of the common reed (Phragmites australis /Cav./ Trin. ex Steudel) was studied in various reed stands in the littoral zone of Lake Fertõ. Measurements were performed in three healthy and two dieback reed stands in the summer of 1997. In the leaves of declining reeds, the chlorophyll content was lower than in the vigorous sites. In the former sites, there was a significant rise in the total carotenoid pool (320–480 mmol mol−1chl (a + b)) as compared to that of the vigorous sites (250–350 mmol mol−1 chi (a + b). The size of the xanthophyll cycle pool and the β-carotene content of leaves significantly increased in the die-back sites. In early summer, the potential photochemical quantum efficiency of Photosystem II (Fv/Fm) did not differ considerably (0.79–0.81) from site to site, yet by August it significantly decreased (0.74–0.77) in the die-back sites as compared to the vigorous sites. The maximum CO2 assimilation rate measured on the 3rd and 4th leaves ranged from 11 to 17 CO2μmol m−2 s−1 and from 9 to 12 CO2μmol m−2 s−1 in the vigorous sites and the die-back sites, respectively. The stomatal conductance was also lower in the die-back sites (200–350 mmol H2O m−2 s−1) than in the vigorous reed stands (380–510 mmol H2O m−2s−1) which might result in the functional impairment of the gas ventilation system of the declining reeds, and consequently in oxygen deficiency and damage to the rhizome.

Comparison between biomass and C, N, P, S contents of vigorous and die-back reed stands of Lake Fertő/Neusiedler See

The production of vigorous and die-back sites of the same reed belt and nutrient content of reed were studied to detect possible causes of reed die-back. Shoot density, total aboveground and belowground biomass and their C, N, P and S contents were also determined.Samples were collected from three vigorous and three die-back sites of Lake Fertő/Neusiedler See in 1996 and 1997. Reed stands were compared when the biomass was maximal in both years. Reed shoots were significantly (p = 5%) shorter, thinner and had less internodes at the die-back sites than at the vigorous sites, where the aboveground biomass was 1.5–2.0 times and the leaf area index (LAI) 1.7–2.5 times higher. The belowground biomass was nearly the same at the vigorous and die-back sites. The amount of decaying belowground biomass was less than 50% of the total belowground biomass at the vigorous sites, while it reached 75% at the die-back sites.Different N, C, P and S concentrations were found in the reed organs studied (leaves, culm, rhizome and roots). The N concentration in leaves, culm and rhizome was higher at the die-back sites, where the P concentration was the lowest. There were no significant differences in the S concentration of the examined reed organs as comparing the vigorous and degraded reeds. The C concentration of culms were higher, while that of the living rhizomes were lower at healthy than at the die-back sites. The N, P, C and S standing stocks in the aboveground biomass were significantly lower at the die-back sites than at the vigorous sites. In the belowground biomass the P standing stock was significantly lower, while the N standing stock was significantly higher at the die-back sites than at the vigorous sites.Not more than 17% of the total dry mass m−2, 17% of the C, 24% of the N, 14% of the S and 27% of the P standing stock was found in the aboveground phytomass produced in the actual year.

Reed Stand Conditions at Selected Wetlands in Slovenia and Hungary

We determined the characteristics of reed stands at an intermittent lake in Slovenia and degraded and vital reed stands in Hungary. The disturbance in reed performance was measured through growth analysis, amino acid analysis in basal culm internodes, and photochemical efficiency of photosystem II (PSII) in leaves. Morphological parameters indicated higher disturbance in the development of degraded and intermittent reed stands in comparison to vital reed stands. Similarly, total free amino acid contents in basal culm internodes reflected temporary stress response in degraded and intermittent reed stands. On the other hand, potential photochemical efficiency showed undisturbed energy harvesting of all reed stands, even though actual photochemical efficiency revealed temporary disturbance of PSII. The most unfavourable condition for reed development seems to be degraded reed stand of Kis-Balaton wetland and littoral reed stand of intermittent Lake Cerknica.

Effects of the introduction of pre-treated wastewater in a shallow lake reed stand

Abstract Reed stands may be employed in the amelioration of water quality or even in the treatment of wastewater. In this study, the nutrient concentrations of (i) the above- and below-ground Common Reed (Phragmites australis) biomass, and (ii) surface and interstitial water were analyzed in a natural stand used in wastewater treatment. The reed stand was located in Hungarian part of Lake Fertő/Neusiedler See, by the shore near Fertőrákos Bay. The nitrate, phosphate and dissolved organic nitrogen concentrations of surface water were found to be higher on the inlet side of the reed stand compared to the outlet. The N and P concentrations in the above-ground biomass and P concentrations in the below-ground biomass increased after the introduction of pre-treated wastewater. The inter-annual differences in the characteristics of sediment interstitial water and in the nutrient content of reed tissues were assessed using statistical methods. The samples taken before and after the introduction of the pre-treated wastewater in the parcel formed different clusters. The results of the study provide further evidence that the nutrient retention capacity of natural stands of P. australis may be employed in the treatment of wastewater while protecting and preserving the valuable natural assets of the lake.

Limnological characteristics of a Danube oxbow-lake (Danube-Dráva National Park, Hungary)

Spatial and temporal changes in the water chemical parameters and chlorophyll-a concentration were investigated in Kulső-Beda oxbow-lake of the Danube and compared with that of the main channel in 2007-2008. The oxbow-lake water differed from that of the main arm with regards to concentrations of the C, N and P forms. The NO3 - -N, PO4 3- -P, TDN, TDP concentrations were remarkably lower, while the concentrations of DOC, TDC, TOC and of chlorophyll-a were higher in the oxbow-lake than in the main channel. The differences between the NO3 - -N and PO4 3- -P concentrations of the main arm and oxbow-lake decreased with increasing river discharge. The phytoplankton biomass signifi cantly correlated with the TP (r=0.90), NO3 - -N (r=-0.45) concentrations and TDN:TDP ratio (r=-0.47), NO3 - -N:PO4 3- -P ratio (r=-0.55), which suggested P limitation of phytoplankton growth. Signifi cant positive correlation was found between the chlorophyll-a and SPM, POC. The phytoplankton biomass negatively, while NO3 - -N concentration positively correlated with the water discharge of the main arm. The limno- logical characteristics of BDU were dependent on the water regime of the main channel.