Recentni dvoklopniki (Crustacea: Ostracoda) v alpskih izvirih in izvirskih potokih Južnih Apneniških Alp v Sloveniji

The ecology and distribution of ostracods in Alpine springs and springbrooks from Slovenia is presented. Benthos sampling was performed and major environmental characteristics (discharge, substrate composition, temperature, dissolved oxygen, conductivity, pH, alkalinity, sulphate, nitrate, calcium, magnesium) were measured in 12 springs and adjacent springbrooks. Sampling campaign was carried out on six sampling occasions (spring, summer, autumn in 2009 and 2010). Fourteen ostracod species were found among other fauna. The commonest and most abundant species were Psychrodromus fontinalis (Wolf, 1920) and Cavernocypris subterranea (Wolf, 1920), while the other species occurred at one or two sites at the most. Substrate composition and water temperature were statistically significant variables in explaining ostracod assemblages composition in this study.– Prispevek predstavi ekologijo in razširjenost dvoklopnikov (Ostracoda) v alpskih izvirih in izvirskih potokih Slovenije. Vzorčenje bentosa in meritve okoljskih dejavnikov smo opravili spomladi, poleti in jeseni v letih 2009 in 2010 v 12 izvirih in izvirskih potokih. Najdenih je bilo 14 vrst dvoklopnikov. Najbolj pogosti in številčni sta bili vrsti Psychrodromus fontinalis (Wolf, 1920) in Cavernocypris subterranea (Wolf, 1920). Druge vrste so se pojavljale posamično, na eni ali dveh lokacijah. Sestava substrata in temperatura vode sta bila edina statistično značilna okoljska dejavnika, ki sta določala sestavo združbe dvoklopnikov

Contribution to the knowledge on the distribution of Recent free-living freshwater ostracods (Podocopida, Ostracoda, Crustacea) in Slovenia

An updated checklist of Recent free-living freshwater ostracods (Podocopida, Ostracoda, Crustacea) from Slovenia together with new records is presented. The new checklist is based on both the records extracted from the literature and the sampling in the field carried out during the last decade. The present checklist comprises 61 species. However, the eastern part of Slovenia and the surface waters are underrepresented. It is expected that the number of species will increase in the future

Spatial and temporal variability of hyporheic invertebrate community within a stream reach of the River Bača (W Slovenia)

We studied spatio-temporal distribution of hyporheic invertebrate community at the stream-reach scale in the River Bača on three sampling occasions (January, March, May) in 2005. On each sampling occasion, invertebrates were collected from the shallow hyporheic zone (RB1; depth 30-60 cm, 3 replicates), and deeper hyporheic zone (RB2; depth 60-90 cm, 2 replicates) in the river bed, and adjacent gravel bar (GB; depth 60-90 cm, 3 replicates) using Bou-Rouch piston pump. Concurrently, temperature, conductivity and oxygen were measured in the surface water and in hyporheic water at each sampling station. Differences in hyporheic community between dates and habitats were analysed by using two-way ANOVA (dates and habitats as fixed factors) and explored by principal component analysis (PCA). Altogether, 21,657 specimens from 63 taxa were collected. Cyclopoida juveniles, Leuctra sp. (Plecoptera), Chironomidae (Diptera), Acanthocyclops vernalis (Fischer, 1853) and Diacyclops languidus (G. O. Sars, 1863) were the most abundant in the samples. Two-way ANOVA showed significant differences between habitats (RB1 and GB), but no differences between dates when using taxonomic richness as dependent variable. No differences between habitats and dates were calculated when invertebrate densities were applied. PCA of hyporheic invertebrate data showed a gradient in community composition from shallow hyporheic zone (RB1) to deeper hyporheic zone (RB2) and gravel bar (GB). The differences were most probably due to different sediment composition in the studied habitats and less frequent disturbances due to floods in deeper layers and lateral gravel bars

Response of hyporheic biofilms to temperature changes and dissolved organic carbon enrichment: a mesocosm study

Purpose Hyporheic biofilms are the central site for biogeochemical cycling in streams and rivers. In view of global warming and increasing human pressures, this study aimed to compare the response of hyporheic biofilm biomass and activities from an unpolluted reference stream reach surrounded by forest with those from a stream reach exposed to agricultural and urban land use using a mesocosm experiment in which the water temperature and dissolved organic carbon (DOC) contents were manipulated. Methods Hyporheic sediments collected in the field from the two study reaches (i.e. reference and impacted) were incubated in the laboratory at two different temperatures (10 °C, 14 °C) and wetted with three types of synthetic water (control [C] – 0 mg L−1low DOC – 5 mg L−1high DOC – 30 mg L−1) for four weeks. The responses of the hyporheic biofilms were measured weekly using structural (total protein content [TPC] as a proxy for biofilm biomass) and functional measures (electron transport system activity [ETSA] and community-level physiological profiling [CLPP]). Results The response of hyporheic biofilms to temperature changes and DOC enrichment was site-specific for all studied measures (TPC, ETSA and CLPP, including measured average well colour development [AWCD]). The addition of DOC to biofilms from the pristine stream reach significantly heightened the responses at 10 °C, a temperature within the normal environmental temperature ranges of the reference location, but not at 14 °C, which was here, a temperature outside normal environmental range. On the other hand, biofilms from the impacted stream reach exhibited increased responses following DOC enrichment under both temperature regimes, with a particularly pronounced response at 14 ºC, in this case, both experimental temperatures were within the normal environmental temperature ranges of the study locations. Conclusion Hyporheic biofilms were shown to be, like benthic biofilms, sensitive to temperature changes and organic enrichment, but their response to temperature changes and enrichment caused by climate change and/or other anthropogenic pressures (i.e. point and non-point pollution, removal of the riparian zone, hydromorphological modifications, etc.) was not simply linear but site-specific. The intensity of the response, characterized by increased activity and biomass production, appears to be constrained within the temperature ranges prevalent in the environment from which the biofilms originate. These findings emphasize the importance of site-specific considerations in predicting the impacts of climate change and anthropogenic pressures on these critical components of river and stream ecosystems

Macroinvertebrate communities of karst springs in the Julian Alps in relation to environmental factors

Karst springs in the Julian Alps were investigated from May to September 1999 to examine the influence of physical and chemical characteristics on macroinvertebrate community composition. The study revealed a great heterogeneity of environmental characteristics and highly variable taxonomic composition and abundance of taxa among individual springs. The results of canonical correspondence analysis (CCA) showed that spring altitude and periphyton coverage were the only environmental parameters significantly influencing the macroinvertebrate community composition.Karst springs in the Julian Alps were investigated from May to September 1999 to examine the influence of physical and chemical characteristics on macroinvertebrate community composition. The study revealed a great heterogeneity of environmental characteristics and highly variable taxonomic composition and abundance of taxa among individual springs. The results of canonical correspondence analysis (CCA) showed that spring altitude and periphyton coverage were the only environmental parameters significantly influencing the macroinvertebrate community compositio

Macroinvertebrate communities of karst springs in the Julian Alps in relation to environmental factors

Karst springs in the Julian Alps were investigated from May to September 1999 to examine the influence of physical and chemical characteristics on macroinvertebrate community composition. The study revealed a great heterogeneity of environmental characteristics and highly variable taxonomic composition and abundance of taxa among individual springs. The results of canonical correspondence analysis (CCA) showed that spring altitude and periphyton coverage were the only environmental parameters significantly influencing the macroinvertebrate community compositio

Metabolic rates of groundwater species as a function of body mass and temperature

Research on the metabolic physiology of groundwater species, particularly regarding oxygen consumption rates (OCR), has made significant advancement, revealing valuable insights into the adaptations of exclusively groundwater-dwelling (stygobitic) species. However, a comprehensive understanding of how these metabolic rates scale with body mass and respond to temperature changes remains elusive. This study aims to bridge this gap by reviewing published data on OCR across a variety of groundwater organisms to elucidate patterns of metabolic rates in relation to body size and temperature. We employed a combination of literature review and quantitative analyses, focusing on the allometric scaling of OCR with body weight and the effect of temperature on metabolic rates. Our findings indicate that OCR scales with body weight in an allometric pattern, with an inter-species slope of 0.80, suggesting non-isometric scaling. Furthermore, our analysis showed that stygobitic species’ metabolic rates are less responsive to warming than those of non-stygobitic species at low to moderate temperatures. However, at higher temperatures, metabolic rates in stygobitic species decline faster than in non-stygobitic taxa, highlighting a potential vulnerability to global climate change. This study contributes to our understanding of the metabolic strategies of groundwater species, underscoring the need for further research to fully grasp the eco-evolutionary implications of these findings for groundwater conservation