Marta Illyová

Zooplankton of two arms in the Morava River floodplain in Slovakia

The species composition, seasonal dynamic of biomass and density of zooplankton were studied in two arms with a different hydrological regime. The samples were collected in two hydrologically different years — extremely wet in 2002 and extremely dry in 2003. In the first arm the mean annual chlorophyll-a concentration was 31.6 µg L−1 (2002) and relatively high 64.7 µg L−1 during 2003. Mean seasonal zooplankton wet biomass was low and varied: 11.6 g m−3 (2002) and 2.93 g m−3 (2003). Total zooplankton density was high (7,370 N L−1) in 2002, when rotifers predominated in an open water zone and contributed up to 81% of the total zooplankton biomass and 83% of the total zooplankton density. In medial and littoral zone, in total, 22 cladoceran and 15 copepod species were identified. In the second arm the mean annual concentration of chlorophyll-a was high: 74.8 µg L−1 (2002) and 61.4 µg L−1 (2003). Mean seasonal zooplankton wet biomass varied from 92.5 g m−3 (2002) and 44.10 g m−3 (2003). In 2002 the planktonic crustaceans predominated; their mean biomass was 87.1 g m−3 and B. longirostris formed more than 91% of this value. In 2003, the zooplankton density was high (15,687 N L−1), when rotifers contributed up to 94% of this value. The boom of rotifers (58,740 N L−1) was recorded in June 2003. In total, 45 cladoceran and 14 copepod species were recorded in the medial and littoral zones. During observation we concluded that the structure of zooplankton, particularly species composition, abundance, biomass and seasonal dynamics are affected by the fluctuation of water levels in the arms of the rivers’ inundation areas. This unstable hydrological regime prevented the development of planktonic crustaceans.

Zooplankton in a Danube River Arm near Rusovce (Slovakia)

Poor quantity of zooplankton was recorded in a Danube arm situated on the right side of the Danube River in Slovakia (river km 1857) in 2002 and 2003. All over the year the arm is significantly influenced by groundwater by reason of seepage. Because of low mean water temperature (12°C) and poorly developed macrovegetation in particular, the arm reminds gravel pit-like. The annual average of zooplankton biomass was low and ranged from 0.35 g m−3 (2002) to 1.28 g m−3 (2003), because of low crustacean abundance. Total cladoceran abundance was excessively low in both years and ranged from 3.5 N L−1 (2002) to 16.6 N L−1 (2003). Small species, Bosmina longirostris and Chydorus sphaericus were dominant. Only four adult Copepoda — Cyclops vicinus, Thermocyclops crassus, Eurytemora velox and Eudiaptomus gracilis — were recorded in quantitative samples of both years. In the zooplankton assemblage dominated rotifers (Synchaeta pectinata, Synchaeta oblonga, Polyarthra dolichoptera and Keratella cochlearis) which represented 78% and 67% of total abundance respectively. The total of 19 species of rotifers, 34 Cladocera species and 16 taxa of Copepoda were found.

Discrimination between four Simocephalus species from Slovakia using a PCR-RFLP technique

Planktonic crustaceans are traditionally identified based on morphological and morphometric characters. However, such characters may be hardly distinguishable and often overlap between species. A probability of misidentification is thus relatively high. Molecular techniques may increase the accuracy of identification if appropriate markers are used. Aim of our work was to develop a simple molecular procedure enabling discrimination between four species of Simocephalus occurring in Europe. PCR-RFLP technique proved to be suitable for such discrimination. Within the 709 bp fragment of mitochondrial cytochrome c oxidase subunit 1 gene we found unique combinations of restriction sites of the BbsI and SacI enzymes for Simocephalus vetulus, S. exspinosus, S. serrulatus and S. congener. PCR products of samples from several locations in Slovakia were digested with the two enzymes and electrophoresed on an agarose gel. The restriction patterns were clearly visible and easily distinguishable. This method is applicable for identifying the four species in any life-stage. Considering its simplicity and cost-effectiveness it can be widely used as a diagnostic tool for discriminating between Simocephalus species with overlapping morphologic characters.

Rhynchotalona falcata (Crustacea: Anomopoda: Chydoridae): First recording in Slovakia with notes on its distribution and biology

Abstract Rhynchotalona falcata (G.O. Sars, 1861) was found in the plankton of a gravel pit located in the lowlands of Slovakia. This is the first record of this taxon for Slovakia, although it is widely distributed in Western Europe. We do not know to date, whether it is a rare, native species of Slovakian fauna, or accidentally introduced one from north-west regions of Europe. Some notes on its biology and distribution in Europe are provided.

Downstream effect of a pumped-storage hydropower plant on river habitat conditions and benthic life – a case study

Abstract In spite of many investigations about the impact of reservoirs on river continuum, the downstream effects of a pumped-storage hydropower plants (PSHP) still have been less known. The aim of the study was to evaluate the downstream effect of the PSHP Čierny Váh in regard to the Serial Discontinuity Concept assumptions or studies assessing more frequent types of hydropower reservoirs. We predicted that the increase of water temperature and the alteration of food sources will hierarchically be the most relevant factors determining macroinvertebrate community composition. We focused on mayflies, caddisflies and non-insect benthic invertebrates due to their appropriate responses to discontinuity. We also determined the influence of the hydropower plant on life cycles and productions of the most abundant species of mayflies and caddisflies. We recorded the unique effect of the PSHP Čierny Váh on its downstream environmental variables. According to the nested ANOVA results, temperature regime, transported organic matter, benthic fine particulate organic matter and periphyton biomass were the environmental variables significantly modified by the river discontinuum. Significant differences were also found in the case of macroinvertebrate species richness, density and diversity. Nevertheless, based on the forward selection test for predictor effects, none of the environmental variables affected the macroinvertebrate assemblages significantly. However, the redundancy analysis revealed a separated group of macroinvertebrates preferring conditions characteristic for the site immediately below the reservoir. Regarding the impact of the reservoir on life histories, we revealed the shift in hatching, emergence and duration of life cycles of the abundant mayflies (except Baetis rhodani) and caddisfly Ecclisopteryx dalecarlica. Total annual production of mayflies as well as caddisflies was several times higher at the site immediately below the reservoir. Although PSHP Čierny Váh matches the SDC assumptions (except thermal stratification), the downstream impact resembles much more the effects of small reservoirs or epilimnetic-release reservoirs.

Interaction of Ciliate Communities with Cyanobacterial Water Bloomin a Shallow, Hypertrophic Reservoir

The response of ciliate communities to cyanobacterial bloom was investigated in a shallow, hypertrophic reservoir in Slovakia, central Europe. Seasonal dynamics of ciliate communities corresponded negatively with course of water bloom formation. The highest numbers and abundances of ciliate species occurred during the spring season when cyanobacterial bloom was not fully developed, while there was an abrupt decrease in both numbers and abundances at the beginning of summer when water bloom culminated. Cyanobacterial blooming thus significantly lowered diversity and equitability of ciliate communities: many rare and sporadic species disappeared and few common taxa flourished and dominated. Nonetheless, these leading ciliates formed a functionally diverse assemblage whose members showed mostly positive contemporaneous and only rarely time-shifted interactions. There were fine filter feeders (Cinetochilum margaritaceum, Dexiotricha granulosa, Paramecium caudatum and Spirostomum teres) grazing heterotrophic bacteria and picocyanobacteria, omnivorous fine to coarse filter feeders (Frontonia leucas) as well as hunters (Coleps hirtus, Holophrya teres and Loxophyllum helus) looking for an individual prey. Also a comparatively rich, anaerobic coenosis comprising various bacterivorous armophoreans and plagiopyleans, developed at the bottom of the reservoir. Our study documents that ciliates form functionally diverse communities with potential to control cyanobacterial blooms in hypertrophic reservoirs.

Influence of land use on hyporheos in catchment streams of the Velka Fatra Mts

The historical influence of landscape on the quantitative variables and a special group of hyporheos in streams with similar origin but different catchment landscapes and forest management was studied. The study was conducted in two streams: (i) a preserved forested natural stream where critical ecosystem processes were unaltered by human activities and (ii) a stream with the strong anthropogenic stressors (e.g., logging, agriculture, pasture), impacting the system for the last 500 years. Some parameters were strongly related to these land use: conductivity, fine benthic organic matter (FBOM), orthophosphate (P_PO4) and periphyton content all increased along the gradient from the natural stream to the urban-dominated catchment. The density of interstitial assemblages corresponded with the conductivity (at P < 0.05) and was higher on the stream in urban-dominated catchments; and the Harpacticoida taxa richness, dominated by the family Canthocamptidae, was also greater here. The Multiple Regression Analysis shows that the rate of deforestation had had the most significant effect on the density of hyporheos. Among of crustacean fauna the representatives of epigean harpacticoids from (of) family Canthocamptidae, dominated.