In aquatic ecosystems, the biomass, activity and composition of microorganisms are determined to a large extent by local and regional environmental conditions. While karst aquifers are an important ...source for drinking water, the ecology of microbial communities in karst waters has hardly been studied. This study examined the regional variations and seasonal dynamics of microbial communities in pristine karst spring waters of Slovenia (Central Europe). Fifteen springs distributed across 5 eco-regions exhibiting a strong altitudinal gradient were sampled 4 times a year. Evaluation of the microbial communities included quantification of prokaryotic biomass via total cell counts and microbial activity estimated via measurements of electron transport system activity. The taxonomic structure of the bacterial communities was analysed by terminal restriction fragment length polymorphism fingerprinting. Biological measures were complemented by a set of physico-chemical parameters, including dissolved organic carbon, nutrients, major ions, temperature, electrical conductivity, pH, and dissolved oxygen. Bacterial community structure differed significantly with seasons and eco-regions, with the latter causing greater variation. While the overall power of the environmental variable tested was a moderate factor (15%) in explaining the variability in microbial community structure, catchment altitude was a key determinant. Prokaryotic cell density and microbial activity in spring water decreased with an increase in catchment altitude and were significantly positively correlated. For a better understanding of karst ecosystems and the ecosystem service of water purification, future investigation should address karst microbial communities at a higher phylogenetic and functional resolution.
Elaphoidella thailandensis sp. nov. and E. jaesornensis sp. nov., collected during an investigation of cave-dwelling copepod fauna in the northern part of Thailand, are described and figured herein. ...The new species were collected from pools filled by percolating water from the unsaturated zone of a karstic aquifer in Phitsanulok and Lampang Provinces, respectively. Elaphoidella thailandensis, from Tham Khun cave, is distinguished from its congeners by the two-segmented endopod of pediger 1, the absence of endopod on pediger 4, and the setal formula 4, 5, 6 for the distal exopodal segment of pedigers 2-4. Elaphoidella jaesornensis, from Tham Phar Ngam cave, is distinguished from its most closely related species, E. namnaoensis Brancelj, Watiroyram & Sanoamuang, 2010, by the armature formula of the endopod of pedigers 2-5. The geographical distribution and ecology of Harpacticoida from Thai caves is also presented.
Nannodiaptomus phongnhaensis Dang & Ho, 2001, an endemic stygobiotic diaptomid from Vietnam and the type species of the genus Nannodiaptomus Dang & Ho, 2001, is redescribed on the basis of a new ...material from its type locality: Hang Phong Nha Cave, Quang Binh province, central Vietnam. We also designated a neotype, because the type material has been lost. The diagnosis of the genus is amended, based on the description of the neotype. The taxonomic position of the genus in the subfamily Speodiaptominae is proposed, and its relationships with other genera of this subfamily are discussed. A new cave-dwelling species Nannodiaptomus haii sp. nov., from a cave near the type locality of N. phongnhaensis, is also described and illustrated. The new species differs from the type species of the genus, among other things, by the structure of male's left swimming leg 5, where the inner margin of the apical process and the sub-terminal seta on the swimming leg 5 Exp-2 have small serrated membranes, but these bear 3-4 distinct denticular protrusions in N. phongnhaensis.
A consecutive sediment core (CC2) was drilled in Chen Co (lake) of southern Tibet using a PISTON sampler in 1998 AD. Cladoceran remains including their species, amount richness and ecological ...features are analyzed for the top 117 cm sections of the core, upon which 5 cladoceran assemblages are distinguished. CL0 is an assemblage without any cladocera in the depth between 117–105 cm. CL1 assemblage (depths between 101–77 cm, ca. 1407–1533 AD) possesses total 9 cladoceran species that appear in the core, and performs the greatest richness in the whole sequence. This assemblage reflected that there was plenty of exotic cold water and organic debrises inputing to the sedimentary site under the warmer conditions. The lake was wide and shallow that satisfied the big hydrophyte living. Cladoceran species and richnesses of CL2 assemblage (depths between 77–29 cm, ca. 1533–1831 AD) perform much more decreasing than those of CL1. There was only less Chydorus sphaericus which was acclimatized to wide environmental ranges. This implied that the sedimentary environment is so execrable that most of cladoceran lost their living abilities. Compared with CL1 assemblage, CL3 assemblage (depths between 29–10 cm, ca. 1831–1941 AD) possesses nearly the same dominant species but lower richnesses. Especially, the cladoceran preferring organic debris also decrease in their amounts. This meant that the surface vegetation in the drainage basin was still poor though the environment turned to be better. Except the 2 Zooplankton species, the other 7 species of cladoceran in this core are found in CL4 assemblage (depths between 10-0 cm, ca. 1941–1998 AD), in which the eurythermal species had not performed their competition ability comparing with narrow-temperatures adapted species. It implied that water temperatures were stable and much more influenced by air temperatures under the shallow-water conditions. The environmental features reflected by cladocera assemblages of CC2 core are fully supported by the evidences from ostracoda assemblages, diatom-salinity transfunction, environmental magnetism and relative proxies of the parallel CC1 core. Cladoceran assemblages in the lake sediments of Tibetan Plateau are sensitive to sedimentary environment and very significant to the studies of environmental changes.
Floodplains are vital components of river ecosystems and play an important role in carbon cycling and storage at catchment and global scales. For efficient river management and conservation, it is ...critical to understand the functional role of spatiotemporally complex and dynamic habitat mosaics of river floodplains. Unfortunately, the fundamental understanding of mineralization and carbon flux patterns across complex floodplains is still fragmentary. In this study, respiratory potential (i.e., electron transport system activity ETSA) was quantified seasonally across different aquatic and terrestrial habitats (wetted channels, gravel bars, islands, riparian forests, and grasslands) of 2 Alpine floodplains differing in climate, altitude, discharge, flow alteration intensity, and land use (Soča natural flow regime, 12% grassland area and Urbach mean annual discharge reduction by 30% due to water ion, 69% grassland area). In situ respiration (R) was measured, and ETSA–R ratios were calculated to examine differences in exploitation intensity of the overall respiratory capacity among floodplain habitats and seasons. ETSA and R provided potential and actual estimates, respectively, of organic matter mineralization in the different floodplain habitats. Hierarchical linear regression across habitat types showed that organic matter, grain sizes <0.063 mm, and water content were the most important predictors of ETSA in both floodplains, and grain sizes 2–0.063 and >8 mm were also highly important for the Soča floodplain. The combination of ETSA and R measurements conducted in contrasting floodplains increased our understanding of the relationships between floodplain habitat heterogeneity, organic matter mineralization and human impacts, that is, structural–functional linkages in floodplains. These data are integral towards predicting changes in floodplain function in response to environmental alterations from increasing human pressures and environmental change.
Metabolic potential and respiration rate have been measured in the early life stages of native marble trout Salmo marmoratus (MT), introduced brown trout Salmo trutta (BT) and their hybrids ...(MH = female of MT × male of BT and BH = female of BT × male of MT) to examine the differences in their metabolic characteristics. Metabolic potential and respiration rate were lowest in each developmental stage in MT, followed by MH, BT and BH. The ratio between metabolic potential and respiration rate (ETS/R) in larvae was also lowest for MT (1.0) and MH (1.1), followed by BT (1.4) and BH (1.6), indicating more intensive exploitation of metabolic potential for actual respiration in MT (100%) and MH (~90%) than in BT (~70%) and BH (~60%). Lower ETS/R means a disadvantage in the case of enhanced metabolic activity due to insufficient enzyme machinery needed for energy production. Thus, potential and actual metabolic activity and ETS/R ratio could account for the different competitive abilities among pure trout species and their hybrids in a particular environment. This is the first report on biochemical and physiological differences between pure MT and their hybrids. The combination of metabolic and respiration rate measurements appears to be a useful tool for estimating the metabolic properties in the early developmental stages of fish.
Groundwater is a hidden global keystone ecosystem Saccò, Mattia; Mammola, Stefano; Altermatt, Florian ...
Global change biology,
January 2024, 2024-Jan, 2024-01-00, 20240101, Letnik:
30, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a ...period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Disregarding the importance of groundwater as an ecosystem ignores its critical role in preserving surface biomes. To foster timely global conservation of groundwater, we propose elevating the concept of keystone species into the realm of ecosystems, claiming groundwater as a keystone ecosystem that influences the integrity of many dependent ecosystems. Our global analysis shows that over half of land surface areas (52.6%) has a medium‐to‐high interaction with groundwater, reaching up to 74.9% when deserts and high mountains are excluded. We postulate that the intrinsic transboundary features of groundwater are critical for shifting perspectives towards more holistic approaches in aquatic ecology and beyond. Furthermore, we propose eight key themes to develop a science‐policy integrated groundwater conservation agenda. Given ecosystems above and below the ground intersect at many levels, considering groundwater as an essential component of planetary health is pivotal to reduce biodiversity loss and buffer against climate change.
Groundwater is not only the largest unfrozen freshwater resource on Earth but also a living system hosting unique biodiversity that is subjected to mounting anthropogenic pressures. We mapped groundwater biodiversity and its overlap with surface biodiversity at a global scale, demonstrating that over half of the land surface ecosystems have a medium‐to‐high interaction with groundwater. Given that surface and subterranean systems intersect at many levels, considering groundwater as a keystone ecosystem in global conservation policies appears essential to reduce biodiversity loss and buffer against climate change.
The microdistribution and diversity dynamics of Copepoda (Crustacea) were studied in a 75 m long horizontal karstic cave in the central part of Slovenia from February to December 2000. The only water ...sources in the cave are drips from percolating water. The cave has thin roof, varying from 2 to 10 m. The period studied was characterised by long dry periods, interspersed with several intensive rain-storms and periods of moderate rain. Water bodies were of three different types: small basins on the walls, basins on calcareous sinter on the floor and puddles in the clay. The volume of basins varied from about 0.1 l to more then 50 l. In total, 1989 specimens of 12 taxa were collected from 19 puddles and basins on eight sampling dates. One cyclopoid and eleven harpacticoid taxa were collected, three of them being new to science. All taxa but one (Phyllognathopus vigueri) are stygobionts. The copepod community was dominated by Speocyclops infernus, representing about one half of all copepod specimens collected in the cave. Very few copulas or egg-carrying females were observed during sampling.PUBLICATION ABSTRACT
Whether electron transport system (ETS) activity could be used as an estimator of crayfish thermal tolerance has been investigated experimentally. Food consumption rate, respiration rates in the air ...and water, the difference between energy consumption and respiration costs at a given temperature (‘potential growth scope’, PGS), and ETS activity of Orconectes limosus and Pacifastacus leniusculus were determined over a temperature range of 5–30°C. All concerned parameters were found to be temperature dependent. The significant correlation between ETS activity and PGS indicates that they respond similarly to temperature change. The regression analysis of ETS activity as an estimator of thermal tolerance at the mitochondrial level and PGS as an indicator of thermal tolerance at the organismic level showed the shift of optimum temperature ranges of ETS activity to the right for 2° in O. limosus and for 3° in P. leniusculus. Thus, lower estimated temperature optima and temperatures of optimum ranges of PGS compared to ETS activity could indicate higher thermal sensitivity at the organismic level than at a lower level of complexity (i.e. at the mitochondrial level). The response of ETS activity to temperature change, especially at lower and higher temperatures, indicates differences in the characteristics of the ETSs in O. limosus and P. leniusculus. O. limosus is less sensitive to high temperature. The significant correlation between PGS and ETS activity supports our assumption that ETS activity could be used for the rapid estimation of thermal tolerance in crayfish species.
•ETS activity was studied as an estimator of crayfish thermal tolerance.•ETS activity and scope for growth responded similarly to temperature change.•ETS activity in crayfish species responded to temperature change differently.•ETS activity could be used for the estimation of thermal tolerance of crayfish species.
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