Eva Bulánková

Influence of seasonal variation on bioassessment of streams using macroinvertebrates

The EU Water Framework Directive requires assessment of the ecological quality of running waters using macroinvertebrates. One of the problems of obtaining representative samples of organisms from streams is the choice of sampling date, as the scores obtained from macroinvertebrate indices vary naturally between seasons, confounding the detection of anthropogenic environmental change. We investigated this problem in a 4th order calcareous stream in the western Carpathian Mountains of central Europe, the Stupavský potok brook. We divided our 100 m study site into two stretches and took two replicate samples every other month alternately from each stretch for a period of 1 year, sampling in the months of February, April, June, August, October and December. Multivariate analysis of the macroinvertebrate communities (PCA) clearly separated the samples into three groups: (1) April samples (2) June and August samples (3) October, December and February samples. Metric scores were classified into two groups those that were stable with respect to sampling month, and those that varied. Of the metrics whose values increase with amount of allochthonous organic material (ALPHA_MESO, hyporhithral, littoral, PASF, GSI new, DSI, CSI), the highest scores occurred in February, April, October and December, while for metrics whose values decrease with content of organic material (DSII, DIS, GFI D05, PORI, RETI, hypocrenal, metarhithral, RP, AKA, LITHAL, SHRED, HAI) the highest values occurred in February, April, June and December. We conclude that sampling twice a year, in early spring and late autumn, is appropriate for this type of metarhithral mountain stream. Sampling in summer is less reliable due to strong seasonal influences on many of the metrics examined while sampling in winter is inappropriate for logistical reasons.

Preimaginal stages of Diptera (excluding Chironomidae and Simuliidae) of mountain lakes, their inlets and outlets in the Tatra Mountains (Slovakia)

The occurrence of preimaginal stages of Diptera (excluding Chironomidae and Simuliidae) in the Tatra Mountain lakes, their inlets and outlets, and the influence of acidification on the presence of these taxa were assessed. At 21 sites, 18 Diptera taxa were recorded in 2000 and 2001. The most frequent were Dicranota sp. (73%), Pedicia (C.)rivosa (50%) and Wiedemannia sp. (14%). Diptera were ordinated by RDA; relationships between taxa and environmental variables were significantly determined by temperature and habitat characteristics (altitude, habitat, alkalinity, Ca2+, pH, temperature, conductivity). The RDA diagram confirmed the existence of four Diptera assemblage groups corresponding with four habitat types. Group 1 — alpine and subalpine oligotrophic lakes at higher altitudes threatened by acidification, with the acid tolerant taxa Tipula rufina, T. alpium, Dicranota sp. and Rhypholophus sp. Group 2 — subalpine oligotrophic lakes not threatened by acidification with the acid sensitive taxa Wiedemannia sp., Hemerodromia sp., Tipula (S.) benesignata, Orimarga sp., Chionea sp., Pedicia (C.) rivosa and Bazarella subneglecta which prefer higher temperature. Group 3 — subalpine oligotrophic lakes, with the acid sensitive species Berdeniella illiesi, which prefers cold water. Group 4 — outlets of submontane oligotrophic lakes with characteristic taxa Tricyphona sp. and Tipula goriziensis. Acidified alpine and subalpine Tatra lakes are situated mostly at higher altitudes (1705–2145 m. a.s.l.) and have specific taxonomic composition.

River morphology of mountain streams influenced by an extreme windstorm in the High Tatra Mountains (northern Slovakia)

In this study we describe how the river morphology of seven High Tatras streams has been influenced in different ways by a severe windstorm that occurred in November 2004. A control site situated in an undisturbed area is compared with six sites in windstorm damaged areas. In 2009–2010 River Habitat Survey (RHS) was used to assess the character of 500 m lengths of stream and to derive associated morphological indices (HQA, HMS sensu Raven 1998, RHS indices sensu Vaughan 2010). Large amounts of large woody debris in the channel influenced the streams despite most of it having been removed after the windstorm. Streams situated in deforested valley slopes were probably more affected by erosion; they had higher amounts of transported inorganic matter and also depositional bar features. Some changes in land-use had occurred with streams situated on the south-east side of the High Tatras having a more uniform banktop vegetation structure than the other streams. Distinct secondary succession of bank top vegetation was observed along windstorm influenced streams. The highest percentage of shrubs occurred where impacted streams remained untouched. Morphologically, the streams most affected by windstorm are those situated in deforested steep valley slopes that are affected by erosion and siltation.

Caddisflies (Trichoptera) as good indicators of environmental stress in mountain lotic ecosystems

We analysed the influence of environmental stress (mainly deforestation of catchment due to windstorm) on taxonomic structure as well as composition of functional groups (FG) based on zonation preferences and feeding types of caddisfly species in 11 streams (12 sites) with various environmental conditions situated in the High Tatra Mts, Slovakia. Using Spearman correlation, we confirmed an expected positive association between taxonomic and functional groups richness (Ri), diversity (Shannon — Wiener Index) (Di) and equitability (Eq), but not with habitat diversity (HQA indices). By testing measured physiographical, physico-chemical and hydromorphological factors using CCA analysis we found that stream order and temperature best explained the functional and taxonomic structure of caddisfly assemblages. The occurrence of Rhyacophila glareosa decreased with increasing daily mean water temperature positively correlated with deforestation, whereas R. tristis (dominating at sites most affected by erosion) showed the opposite pattern. Composition of functional groups based on zonation preferences and feeding types distinguished well near natural sites from impacted ones, dominated by crenal/rhithral predators, and explained more of the overall variance of the species-environment relationships than taxonomic composition of caddisfly assemblages.

Caddisfly assemblages of high mountain streams (The High Tatra Mts, Slovakia) influenced by a major windstorm event

Hydrobiological research of high mountain streams in the High Tatras was carried out in 2009–2010. We evaluated the influence of windstorm on caddisfly assemblages. To assess the influence of windstorm we focused on river morphology using the RHS method and evaluation of TAM, TOM and BOM (CPOM, FPOM, UFPOM) amount in seven streams. Site 1 was a control and the other six were disturbed by the windstorm in different ways. The most remarkable differences compared to the control site was in feeding structure at sites most affected by erosion. In these streams there was a noticeable dominance of predators from the family Rhyacophilidae (mainly Rhyacophila tristis; sites 3, 4, 5, 6) and a remarkable decrease of passive filter feeders (site 4, 5). Using Spearman coefficient we confirmed a positive correlation between the proportion of predators and amount of TAM caused by erosion of steep deforested slopes of windstorm affected sites. In contrast, we did not observe such an increase in the proportion of predators at site 7, which was affected by both windstorm and subsequently by fire. This might be explained by the shallow vee valley with no observed erosion, where this site is situated. We also found a negative correlation between predators and evenness, indicating unstable community structure clearing succesion in the streams disturbed by erosion, and a negative correlation between passive filter feeders and UFPOM. We found out that overhanging tree boughs and LWD had an influence on species composition. RHS was a useful tool in characterising the influence of hydromorphology on caddisfly assemblages.

Bioassessment of streams based on macroinvertebrates — can sampling of some substrate types be excluded?

Abstract Attempting to help reduce the costs of bioassessment of aquatic habitats, the aim of this study was to estimate how particular substrate types influence the ecological quality evaluation based on a multihabitat scheme proposed by the AQEM/STAR consortium. Samples of macroinvertebrates were taken from the Stupavský potok brook, a small, 4th order calcareous stream in the Small Carpathians in Slovakia (Central Europe). Eight most suitable metrics for small Slovakian streams forming the Slovak multimetric index on seven substrate types were tested and compared with the multihabitat sample. The Saprobic Index (SI) and Index of Biocenotic Region (IBR) showed considerably worse (higher) values in the psammal and the best (lowest) values on coarse mineral substrates (lithal, akal). Similarly, values of the metrics Oligo (%), BMWP Score, Rheoindex, Rhithron Typie Index (%) and EPT reached their worst (lowest) values on psammal and the best (highest) values on coarse mineral substrates. Psammal sample showed the worst ecological quality expressed by the lowest EQR (Ecological Quality Ratio) value, most significantly differing from the multihabitat sample (Multiple Comparisons of Means: Dunnett Contrasts: –8.25, P < 0.01). We conclude that substrate types considerably influence selected metrics. Because of a relatively substantial proportion of psammal in some small Slovakian streams and its marginal influence on the overall ecological quality of the site, we suggest conduct further research addressing the effectiveness of its usage in the water management.

Testing for longitudinal zonation of macroinvertebrate fauna along a small upland headwater stream in two seasons

Abstract The effect of longitudinal zonation patterns and macroinvertebrate responses to changes in habitat characteristics have been given a lot of attention. But studies of changes in macroinvertebrate assemblages along small upland undisturbed watercourses are still lacking. The aim of the study is to analyse variability in macroinvertebrate communities between two different habitats/morphological sequences – shallow (riffle/run/step/) and deeper (pool) channel-bed morphological units on the background of the environmental parameters (local relief, slope, channel confinement ratio, channel-valley walls connectivity, floodplain continuity and channel abut, channel sinuosity and predominant land cover of riparian zone) of seven valley segments (functional process zones) in two seasons of the year (spring and autumn). The longitudinal-downstream gradient research was conducted on the semi-natural upland headwater brook in the Little Carpathians (9,330 m long, average gradient 2.8%) at 15 morphological sequences (30 sampling points). Each sampling point in spring as well as in autumn was characterised by mean flow velocity, discharge, water depth, channel width, channel bottom particle size, and flow types. Selected physico-chemical variables: pH, dissolved oxygen content (DO), oxygen saturation (DO %), temperature (t) conductivity and total dissolved solids (TDS) were measured directly in the field using the multisonde measuring device. Organisms were identified into the family level. The results showed that differences in zonation of benthic invertebrates between seasons are more apparent than seasonal variability between pools and riffles. Spring samples followed the increasing gradient of total dissolved solids downstream with characteristic families for upper and lower stretch. The disruption of macroinvertebrates zonation was more evident in autumn samples with greatest effects in pools. Based on RDA, the distribution of families was driven by three significant variables in riffles and four in pools. Alike environmental factors of pool sequences in the middle and upper reaches were responsible for similarity in macroinvertebrate structure. In conclusion, the distribution pattern of benthic invertebrates of the natural part of the small headwater stream in terms of abundance of macroinvertebrate families followed the longitudinal zonation in spring, but in autumn were the local habitat conditions more important.

Benthic macroinvertebrates along the Czech part of the Labe and lower section of the Vltava rivers from 1996-2005, with a particular focus on rare and alien species

In the Czech part of the Labe River and the lower part of the Vltava River, we examined if the benthic macroinvertebrate composition changed from 1996 to 2005 due to expected improvements in water quality resulting from socioeconomic changes in the Czech Republic since the 1990s. Special attention was given to rare and alien species. The four biological metrics used (Number of taxa, BMWP, Number of sensitive taxa, and Number of EPT taxa) demonstrated that there was indeed an improvement in water quality as well as a slight improvement of the Labe microhabitats during the investigated period. An increasing Number of taxa over time was observed at most sites. Two main concurrent ecological processes are recently in progress in the Labe: a recovery of native species and an expansion of alien species, some of which are considered invasive. The caddisfly Setodes punctatus and the beetle Pomatinus substriatus, considered as regionally extinct in the Czech Republic until 2005, were rediscovered during our investigations. Findings of the crustacean Hemimysis anomala (invasive) and the chironomids Stenochironomus sp. and Lipiniella sp. were the first records of these taxa in the Czech Republic.

New records of Aeshna subarctica elisabethae (Odonata, Aeshnidae) from the Tatra Mountains (Slovakia)

Aeshna subarctica elisabethae Djakonov, 1922 belongs to the endangered species of dragonflies in Slovakia (David, 2001). This boreo-montan species is a rare inhabitant of bogs and boggy marshes with Sphagnum sp. Eutrophication renders water unsuitable for Aeshna subarctica Walker, 1908 (Askew, 1988). In the High Tatra Mts, we found one larva and some imagoes in a small shallow raised bog with dominant moss Sphagnum sp. and some rare plant species: Oxycocus palustris, Scheuchzeria palustris, Carex pauciflora, Drosera rotundifolia, Eriophorum vaginatum, Carex limosa. Material examined: High Tatra Mts (49◦07.488′ N, 20◦03.208′ E), 1379 m a.s.l., 1 larva, 2.X.2002, leg. T. Derka, det. et coll. E. Bulánková; 1 , 14 exuviae, 5.VII. .2003, leg. et det. D. Šácha; 6 , 1 , 4 exuviae, 9.VII. 2003, leg. et det. D. Šácha; 2 , 1 , 8 exuviae, 24.VIII.2003, leg. et det. D. Šácha; 1 exuvium, 7.VI.2004, leg. et det. D. Šácha. The dragonflies associated with this habitat were Aeshna juncea (L., 1758), Somatochlora alpestris (Sélys, 1840) and Leucorrhinia dubia (van der Linden, 1825). Janský & David (1997) found Aeshna subarctica elisabethae in raised bog Klinské rašelinisko (NW Slovakia). Out of the High Tatra lakes, some larvae of this species were found in Jamské pleso (Trpiš, 1965; Krno, 1991), Tatranská kotlina basin, Javorina, in Štrbské pleso (Trpiš, 1965) and in Nižné Rakytovské pleso (Lukáš, 1995). Larvae occur together with Aeshna juncea and it is a problem to distinguish Aeshna subarctica from Aeshna juncea which had been previously confused (Askew, 1988). The occurrence of larvae and imagoes together confirm the breeding of Aeshna subarctica elisabethae in mentioned acid pool.