Joanna Galas

Water temperatures and ice cover in lakes of the Tatra Mountains

In 2000 and 2001, miniature thermistors with integrated data loggers were employed to measure lake surface water temperatures (LSWTs) and temperature profiles in high-altitude mountain lakes lying between 1580 and 2145 m a.s.l. on both the Slovak and Polish sides of the Tatra Mountains. This allowed the annual cycle of water temperatures and ice cover in these lakes to be described quantitatively, and their dependence on lake altitude above sea level to be investigated. LSWTs in the Tatra Mountains are found to decrease approximately linearly with increasing altitude from late spring to autumn. LSWT in summer can be modelled well in terms of exponentially smoothed ambient air temperature. Although the timing of ice-off is dependent on altitude, the timing of ice-on is not; the dependence of the duration of ice cover on altitude is therefore wholly due to the altitudinal dependence of the timing of ice-off. The temperature profile measurements allow quantitative characterization of summer and winter stagnation, and spring and autumn turnover.

Littoral benthic macroinvertebrates of mountain lakes in the Tatra Mountains (Slovakia, Poland)

Littoral benthic macroinvertebrates of 45 mountain lakes in the Tatra Mountains were sampled using a semi-quantitative method in September 2000. A total of 32,852 specimens were identified to 93 taxa belonging to 14 higher taxonomic groups. Multivariate statistics (CCA, RDA) and nine biotic metrics (AQEM/STAR) were used to explain relationships between macroinvertebrate assemblages and environmental variables. Up to 57% of the ecological position of littoral macroinvertebrate assemblages were explained by variance of environmental variables divided into chemical, trophic, physical, catchment and location. Five types of Tatra lakes were recognized using CCA: A — strongly acidified lakes (small catchment, low pH, high concentration of TP, DOC, highest amount of POM in littoral); B — alpine acidified lakes (low amount of POM, low values of biotic metrics); C — alpine non-acidified lakes (high value of diversity index, predominance of Diptera); D — subalpine acidified lakes (high values of biotic metrics: number of families, proportion of crenal and rhithral taxa/total taxa); E — subalpine non-acidified lakes (high values of biotic metrics: number of families, number of genera, BMWP score, number of taxa and abundance of EPT taxa). RDA was used to design five levels of macroinvertebrate taxa acidification tolerance. The Tatra Acidification Index (TAI) was established to assess the acidification status of the lakes in the Tatra Mts.

Factors affecting the distribution of Oligochaeta in small high mountain ponds (Tatra Mts, Poland)

The Oligochaeta communities of six small high mountain ponds were examined. A total of only 17 taxa were found. In temporary ponds and in ponds that freeze to the bottom in winter the community consisted almost exclusively of Enchytraeidae, of which Cernosvitoviella tatrensis was the most numerous species. In other ponds the community composition was more diverse, and the dominant species were Spirosoperma ferox and Nais variabilis. In one of the studied ponds (the Siwy Wyzni) where the water level was stable, there were differences in species composition among various sampling locations. These differences persisted in successive years and the probable reason for that was the presence of springs which led to varying chemical and thermal conditions. The content of organic matter in the mud sediment of the studied ponds was high, varying from 10-30% in most ponds and was high as 50% in one dystrophic pond. Correlations between total Oligochaeta density, or density of the dominant species, and sediment organic matter content were not statistically significant. Among the oligochaete species living in the mountain ponds four ecological types were distinguished.

From spring sources to springbrook: Changes in environmental characteristics and benthic fauna

Spatial patterns in macroinvertebrate communities and some abiotic factors were examined in three rheocrene springs and their springbrooks (Kraków-Częstochowa Upland, southern Poland). The mean discharge of particular springs ranged from 5 to 11 L s−1, and its annual fluctuations were small. Water temperature was very stable at all sampling sites. In the eucrenon the number of benthic taxa was the smallest (9–14 determined to the family level), but the densities were the highest (approx. 14000 ind. m−2). The biggest changes in macroinvertebrate composition were observed in the modified hypocrenon, which is an artificial pond. The lowest number of taxa were found in a natural, short springbrook with a nondiversified bottom substrate. The density of crenophilic taxa (Drusus trifidus, Dugesia gonocephala, Elmidae) diminished along the springbrooks, while the opposite trend was observed for ubiquitous taxa (some Oligochaeta, Asellus aquaticus and Chironomidae). Even in a very short natural springbrook (30 m), Drusus trifidus, the only species of Trichoptera found in the springs discussed here, goes through the entire development cycle. The strongest influence of a big river was observed at the outflow of one of the natural springbrooks, where the highest number of riverine oligochaete species were found. The benthic fauna of the springs studied here differed from that found in other springs in this area — the absence of the typical crenophilic species Bithynella austriaca (Gastropoda) and the presence of Gianus aquedulcis (Oligochaeta) may indicate the autonomy of the spring fauna in the Mstów area, possibly resulting from the postglacial geomorphological formation of this region or differences in habitat conditions.

Temporary co-existence of aquatic and terrestrial invertebrates in shallow periodically flooded and frozen cave

Abstract The effect of specific microclimatic conditions and temporary flooding on terrestrial and aquatic invertebrate community composition as well as on parietal fauna was investigated in a cave located on the Krakow-Wieluń Upland. Studies of the fauna started after partial water retreat from the cave. Microclimate conditions and water chemistry parameters were also investigated. Due to the cave geometry and its size, temperatures recorded during summer were relatively high, whereas almost all its parts were frozen in winter. Temporary cave flooding promoted reproducing populations of Asellus aquaticus, Pseudocandona sarsi and copepods (Diacyclops bicuspidatus, Megacyclops viridis). Completely depigmented (including eyes), slightly, as well as fully pigmented individuals of A. aquaticus were found. Some dipterans started to reproduce in the flooded cave but drying stopped their development. Some taxa typical for terrestrial habitats (Collembola and Acari) and for parietal fauna (spider Meta menardi, moth Triphosa dubitata, dipterans from families Helomyzidae and Mycethophilidae) were not observed. Moreover, cave freezing significantly diminished the number of Culicidae, Oniscus sp., gastropods and Nesticus cellulanus wintering in the cave. The recolonization process was possible due to the cave location at the shallow subsurface and multiple entrances. The diversity of terrestrial invertebrates in the cave is very low as the effect of periodical flooding and freezing.

A comparison of various indices based on benthic macrofauna for the assessment of the ecological status of selected Carpathian streams

The biological indices MMI-PL, BMWP-PL, and %EPT were applied to compare the ecological status of Carpathian flysch stream sectors situated above and below sewage treatment plants. MMI-PL was found to be the most sensitive, whereas BMWP-PL indicated a very good ecological status at all sampling stations despite an increased trophic level of water in polluted sectors. %EPT proved to be an unreliable index because of its strong fluctuations resulting mainly from unstable densities of benthic invertebrate groups not included therein. The analyses of coli titers and water chemistry in the same stream sectors revealed temporary pollution at both types of stations.