Captive breeding of freshwater mussels is essential for conservation strategies to maintain populations of endangered bivalve mollusks. In the Czech Republic, breeders use detritus from natural sources, preferably from nearby streams and spring areas, to prepare pearl mussels for release into the target localities to reestablish sustainable populations in their native habitats. This strategy is subject to sudden changes, and breeders must consider different detritus qualities between seasons and the unpredictability of weather conditions. Therefore, harvesting natural detritus on a regular basis is challenging and time-consuming, and more samples require more testing, which increases the cost of captive breeding. We proved that juvenile freshwater pearl mussels grew faster when fed detritus stored frozen in a freezer than when fed the same chilled detritus. Therefore, detritus can be harvested under optimal conditions and stored in a freezer for the remaining season, thereby simplifying and reducing mussel conservation costs. Moreover, this approach offers a sustainable, environmentally friendly method that does not require the industrial production of artificial feeds.

The freshwater pearl mussel Margaritifera margaritifera (FPM) is an endangered bivalve species occurring in oligotrophic rivers. FPMs can be found in the Upper Vltava River in the Sumava National Park (Czech Republic, Central Europe), where suitable conditions exist for both adult and juvenile mussels. Non-consumptive human leisure activities are known to negatively affect wildlife in fragile aquatic ecosystems, and in the Vltava River boating tourism in particular may be a threat to local mussel populations. This study focused on an assessment of interactions between river tourists and the FPM, using "pseudo-mussels" in both field and lab experiments. In the field, fake concrete mussels were exposed at three rest sites for river tourists, and in the lab experiment glued shells were placed at the water-sediment interface in an aquarium tested for mechanical impacts of paddles (dislodgement and crushing). Interactions of river tourists with fake mussels were most frequent at low water levels (10-20 cm), and within 2 m from the nearest river bank. Mussel visibility and the presence/absence of a guide played an important role in people ' s reactions, but site-specific effects were also found. Unintentional interactions (60-69%) were mostly observed at less-attractive sites (with a limited area of shallow water where people spent most time outside the river channel), whereas visual and manipulative interactions (76%) dominated at a more-attractive site (the confluence of two rivers where people move across and inspect the river channel). Crash tests revealed that 8.03 +/- 1.37 (mean +/- SD) and 7.88 +/- 1.13 (mean +/- SD) hits by paddles were needed for dislodgment and crushing, respectively. Those findings indicate that the direct effects of recreational boating might be less detrimental than those of accompanying activities (such as wading, bathing, and swim-ming). The role of trampling (and handling) disturbances should be investigated in more detail to help conserve FPM populations in protected areas.

As freshwater environments become increasingly threatened, the need for efficient and effective protection grows more urgent. Yet quantitative evidence of management effectiveness within freshwater protected areas is limited, inhibiting our ability to infer the practicality and efficacy of practices. Herein, we employ linear mixed-effects models and time series models to evaluate the connection between catchment-scale management actions and surface water quality within a freshwater protected area, over the past three decades. Within the study area, all croplands were restored to traditional grasslands resulting in a landscape dominated by meadows and forests. The extent of land use change and time frame needed for water quality improvements were investigated and management effectiveness appraised. Results indicate that the complete grassing of croplands was approximately three times more effective at reducing concentrations of nitrate than electrical conductivity and calcium. Significant improvements in water quality occurred within nine years of management implementation, with mean annual nitrate concentrations decreasing from 5.5 to 1.9 mg/L following the grassing of all croplands covering 3.1% of the study area, whereas gradual improvements continued over the next 20 years, ultimately resulting in nitrate concentrations below 1.0 mg/L. The results of this study provide valuable insights on how land use conversions in small headwater catchments can influence stream water quality and helps to establish expectations for outcomes when planning conservation strategies.

Despite the large number of studies devoted to organic matter dynamics in fluvial ecosystems, the detrital pathways of spring headwater systems remain neglected. In particular, spring wetlands (helocrenes or seepages) might have considerable influence on downstream headwater stream systems due to the alteration of the nutrient and organic matter content of the water. In this study, we examined fine particulate organic matter (FPOM) drained from helocrenic springs to describe its downstream transport. We studied the quantity, nutrient content and physical components of FPOM gathered from the outflowing water using continuous sediment samplers. The nutrient content of local leaf litter deposits, residence time of water in the springs and concentration of dissolved nutrients in spring sources and outflows were also measured to characterize the inputs and outputs of the studied system. The results show that headwater spring wetlands represent a significant source of high-quality FPOM for downstream river networks. The estimated concentration of FPOM (<1000 μm) in the 11 investigated springs was 3.1 ± 2.5 mg.L-1. In general, the FPOM was relatively nutrient-rich (N = 19.25 ± 4.73 mg.L-1; P = 2.04 ± 0.78 mg.L-1; Ca = 9.65 ± 2.63 mg.L-1; S = 4.07 ± 1.16 mg.L-1; C = 278.68 ± 80.81 mg.L-1). The C:N and C:P ratios in the local leaf litter deposits were higher than in FPOM (41.04 ± 14.32 vs. 14.70 ± 2.46 and 591.7 ± 168.83 vs. 154,77 ± 64,73, respectively), indicating that suspended FPOM is more nutritious for consumers. A significant trend in terms of size fractions of FPOM was identified: with decreasing C:N and C:P ratios particle size decreases as well. Overall, the data suggest that the relatively small helocrenes can serve as an organic matter transformers, receiving primary particles and dissolved organic matter, transforming them and favouring their transport downstream. These biotopes may represent a substantial discontinuity of the river continuum at its origin, important for nutrient dynamics and food supply of associated biotic communities.

Sediment depth preference was tested on 1-year-old freshwater pearl mussel juveniles. Mesh tubes allowing vertical migration with a possibility to leave hyporheic space, filled with 1–2-mm granulometry size substrate and populated with groups of juveniles, were placed in the natural river bed of the Teplá Vltava River, Czech Republic. The depth position of the juveniles was recorded after 1- and 2-month exposure during the summer and after 8 months including wintering. The juveniles showed a tendency not to stay on the sediment surface, but to penetrate into a very shallow depth, and to accumulate and stay 2–3 cm deep in the substrate in the summer period. No juvenile was found below 8 cm sediment depth, neither in the summer nor after wintering. In the experimental tubes, various survival rates (0–100%) were recorded in close relation to substrate oxygenation development at the tested sites. Oxygen decrease was accompanied by juveniles trying to escape the hyporheal.

Land use is a predominant threat to the ecological integrity of streams and rivers. Understanding land use-water quality interactions is essential for the development and prioritization of management strategies and, thus, the improvement of water quality. Weighting schemes for land use have recently been employed as methods to advance the predictive power of empirical models, however, their performance has seldom been explored for various water quality parameters. In this work, multiple landscape composition metrics were applied within headwater catchments of Central Europe to investigate how weighting land use with certain combinations of spatial and topographic variables, while implementing alternate distance measures and functions, can influence predictions of water quality. The predictive ability of metrics was evaluated for eleven water quality parameters using linear regression. Results indicate that stream proximity, measured with Euclidean distance, in combination with slope or log-transformed flow accumulation were dominant factors affecting the concentrations of pH, total phosphorus, nitrite and orthophosphate phosphorus, whereas the unweighted land use composition was the most effective predictor of calcium, electrical conductivity, nitrates and total suspended solids. Therefore, both metrics are recommended when examining land use-water quality relationships in small, submontane catchments and should be applied according to individual water quality parameter.

ons of visitors were then recorded in terms of observing, manipulating or destroying the species In-situ bioindication was performed in the river based on caging and exposure experiments of juvenile Freshwater Pearl Mussels. After exposure, both juvenile growth rate and survival rate were evaluated within localities where disturbances, erosion or pollution had occured in connection to camps, hotels or settlements (Černá et al. 2018). These described methods have enabled a safe limit for the control of visitors. The national park administration office allows a regulated entrance into the park's core zone and eliminate vistor impacts on macrophytes (priorite habitat V4A Macrophyte vegetation of water streams, with currently present water macrophytes) and critically endangered molluscs (Margaritifera margaritifera L. - Simon et al. 2015). By using precise data, it was possible to carry out these regulations against the strong pressures of boat rental companies and lobbyist. The described methods could be applied in diverse contexts within marine or freshwater ecosystems. Černá, M., O. P. Simon, M. Bílý, K. Douda, B. Dort, M. Galová & M. Volfová, 2018. Within-river variation in growth and survival of juvenile freshwater pearl mussels assessed by in situ exposure methods. Hydrobiologia 810(1):393-414 Křenová, Z. & P. Kindlmann, 2015. Natura 2000 - Solution for Eastern Europe or just a good start? The Šumava National Park as a test case. Biological Conservation 186:268-275 Simon, O. P., I. Vaníčková, M. Bílý, K. Douda, H. Patzenhauerová, J. Hruška & A. Peltánová, 2015. The status of freshwater pearl mussel in the Czech Republic: Several successfully rejuvenated populations but the absence of natural reproduction. Limnologica - Ecology and Management of Inland Waters 50:11-20 Fig.1 Concrete replicas of pearl mussels were utilized in national park core area to assess the risk of removing or destroying the dummy mollusc colony.

The early post-parasitic phase is considered to be the most vulnerable life stage of the endangered freshwater pearl mussel (Margaritifera margaritifera), yet little is known about the spatial variability in juvenile performance at a river scale. The main aim of this study was to determine within-river variation in habitat suitability for juvenile M. margaritifera. The growth and survival rates of juveniles (one and two year old) were measured in the Vltava River (Czech Republic) in relation to several physical and chemical variables using a total of 166 bioindication units (individual mesh cages and sandy boxes) during two thermally different vegetation seasons. Three spatial scales were studied: a longitudinal river profile, bottom habitat types, and hyporheic microhabitats. Both the survival rate and growth of the exposed juveniles varied considerably within the studied river. The effect of the longitudinal river profile and the roles of temperature, oxygenation within microhabitats, episodic pollution, and exposure method were demonstrated. This study represents the first example of a hierarchized approach to the assessment of a riverine mussel biotope with the use of bioindication methods. The results demonstrate the importance of the scale and bioindication method used in understanding the suitability of a river environment to juvenile freshwater mussels.

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol for performing in situ juvenile exposure tests within oligotrophic river catchments over one-month and three-month periods. Two methods (in both modifications) are presented to evaluate the juvenile growth and survival rate. The methods and modifications differ in value for the locality bioindication and each has its benefits as well as limitations. The sandy cage method works with a large set of individuals, but only some of the individuals are measured and the results are evaluated in bulk. In the mesh cage method, the individuals are kept and measured separately, but a low individual number is evaluated. The open water exposure modification is relatively easy to apply; it shows the juvenile growth potential of sites and can also be effective for water toxicity testing. The within-bed exposure modification needs a high workload but is closer to the conditions of a natural juvenile environment and it is better for reporting the real suitability of localities. On the other hand, more replications are needed in this modification due to its high-hyporheic environment variability.

It is well known that land snails can be dispersed by birds, both by attachment to the body (ectozoochory) and by passing intact and alive through the bird's digestive tract (endozoochory). Endozoochory has, however, only been recorded for very small species. We examined the possibility that larger species (up to c. 17 mm in maximum shell dimension) could survive passage through a bird's digestive system. Live Alinda biplicata, Cochlodina laminata (both Clausiliidae) and Discus rotundatus (Discidae) were fed to 10 bird species (Corvidae, Turdidae, Sturnidae and Columbidae) in 14 experimental trials. Of 720 snails offered, 14 passed intact through the birds, of which nine were alive (eight clausiliids and one D. rotundatus); thus more than 1% of all snails offered survived ingestion. In an additional experiment, some A. biplicata and C. laminata remained attached to birds' legs by pedal adhesion in simulated flight trials where the birds' legs oscillated at the maximum rate achieved during flight.

The freshwater pearl mussel was historically abundant in many streams and rivers in the Elbe, Oder, and Danube Basins in the Czech Republic, Central Europe. By the 21st century, the mussels had become extinct in the lower and middle altitudes, and current populations are only present near the upper limit of their natural range. The current population of this mussel is estimated to be only 1% of the historical abundance. The population decline was related to the negative impacts of pollution from industry, intense agriculture, forestry, and sewage water. The freshwater pearl mussel habitat has also been impacted by watercourse regulations and has been fragmented by dams and weirs. All of these impacts have resulted in failure of the reproductive cycle; the last significant cohort of juveniles settled approximately 30 – 40 years ago. Therefore, this species is considered critically endangered, and an action plan was developed to conserve the populations in the Czech Republic. Special measures were conducted between 1984 and 2005 to improve the age structure of elderly populations. Fish infected with millions of glochidia were released in two locations, and over 53,000 captive-bred juveniles that were three to five years old were released in seven locations. Only the latter approach resulted in a small number of subadults that gradually emerged from the substratum to the bottom surface, as confirmed by monitoring efforts. Despite simultaneous efforts to restore mussel habitat over the last 25 years, natural reproduction still does not occur in the Czech Republic. Therefore, complete restoration of oligotrophic streams is the key to the future presence and natural reproduction of freshwater pearl mussels in the Czech Republic.

In recent years, the importance of wastewater treatment in small municipalities has risen as the pollution from agriculture has decreased. A typical example is the municipality of Zbytiny, which requires higher wastewater treatment efficiency than usual for a village of its size. This is because of the occurrence of freshwater pearl mussels in the Blanice River. The wastewater treatment plants (WWTP) designed for municipalities up to 500 inhabitants are efficient for treating organic pollution, but their treatment efficiency for total nitrogen and phosphorus is relatively low. Therefore, a unique solution was chosen in Zbytiny; two low-loaded stabilisation ponds, connected in a series, were built in addition to a new mechanical biological WWTP. These stabilisation ponds are used to post-treat wastewater discharged from the WWTP. The results from two years of regular monitoring clearly show a positive influence of these stabilisation ponds on total treatment efficiency. The best results from post-treatment in the stabilisation ponds were observed for total nitrogen and phosphorus, which showed treatment efficiencies of 38% and 88%, respectively. The water quality in the Zbytinský Potok stream is now closer to the biotope required by freshwater pearl mussels. Furthermore, the nutrient loading of the lower part of the Blanice River has decreased. Today, only nitrate concentrations and conductivity are higher in the stream below the village than above; however, the values are much lower than before the construction of the WWTP.

We analyzed the composition of spring fauna in relation to the mesoscale variability in environmental conditions in 77 permanent springs in a geologically homogenous area. We hypothesized that the species would occur in definite patterns reflecting the differences in factors that operate at the spring-level scale. We focused on the differences resulting from spring morphology, substrate composition, shading, and water chemistry. Our goal was to identify the abiotic variables that control the character of interspecies associations. The spring assemblages comprised species of 9 higher taxonomic groups (Plecoptera, Trichoptera, Coleoptera, Diptera, Turbellaria, Crustacea, Mollusca, Oligochaeta, Hydracarina). We used binomial regression successfully to construct single-species environmental models for several of the most abundant taxa. The most important factors explaining the species' occurrence were hydromorphological and substrate characteristics. Results of nonmetric multidimensional scaling ordination on species composition indicated 3 groups of springs. However, the analysis did not provide evidence for strong interspecies associations. Group 1 separated springs with running water, high substrate heterogeneity, and high taxonomic richness. Groups 2 and 3 included mostly helocrene-like springs differing in slope and substrate composition. The assemblages of these 2 groups comprised the same dominant species. However, the springs from group 3 had lower species abundances. Our study demonstrates the importance of mesoscale differences in habitat conditions for structuring the spring-associated benthic assemblages.

Fine particulate organic matter (FPOM), originated by aggregation of smaller particles and by decomposition of bigger particles, usually presents the dominant energy and nutrient source in the primary river net. Relationships between detrital components, environmental factors and macroinvertebrate composition were investigated in 52 submontane organogenic spring areas in small catchment in the Sumava foothills, Czech Republic. All three types of springs (helocrenes, rheocrenes and limnocrenes) were represented, as well as springs with the transitional character. The selected springs were permanent, with water discharge higher than 0.1 L they all were coldwater and stenothermic, with the winter water temperature at the point of the source ranging from 2.0 to 9.9 degrees C. At each spring area, the main morphological and physical characteristics of the spring and surrounding area were recorded. Samples of detritus were collected (using the 2 mL sampling tube) from up to 5 microhabitats at each spring, usually macrophyte vegetation, point of the source, detrital deposition, sand, algal mat, leaf litter or moss, accordingly to the microhabitats, which were present. Macroinvertebrates were semiquantitatively sampled using a 15-cm circular sampler with 0.8 mm mesh, to the orders or lower taxa were determined. Water samples were taken, and analyses of the main physico-chemical factors were carried out. In our set of springs, organic substrate prevailed. Only small differences in the physico-chemical parameters (e.g. pH = 5.96 +/- 0.39; mean +/- SD) and low concentrations of nutrients (e.g. N-NO3- = 0.79 +/- 0.86 mg L-1, ortho-P-PO4- = 0.0336 +/- 0.0275 mg L-1) were noted, whereas studied geomorphological parameters and micro-habitat types were more diverse. The proportion of basic microscopically differentiable components of the detritus was similar in all spring types and microhabitats. In all study sites, faecal pellet content was dominant in the detritus (49%) followed by plant residuals (26%) and amorphous matter (21%). High faecal pellet content is considered to be a consequence of a steadily low temperature in the springs. The correlation among the presence of macroinvertebrate groups and particular detrital components content was not significant, except for Trichoptera; the abundance of this group was positively correlated with the proportion of plant residuals in detritus in vegetation microhabitats. Faecal pellet content showed a weak negative correlation with N-NH4 concentration, which is probably the result of faster faecal pellet decomposition in springs with higher N-NH4 contents.

This paper presents a part of the results obtained from extensive studies conducted on springs — remarkable freshwater habitats with many unique characteristics and a high degree of biological diversity. The abiotic conditions and fauna composition of 68 submontane permanent oligotrophic springs in the Blanice River catchment (eastern part of The Bohemian Forest, Czech Republic) were investigated with a focus on their relationship to the Pisidium species occurrence. We attempted to determine the habitat requirements of individual pea clam species. Species of genus Pisidium generally preferred unshaded springs with fine substrate, the most favourable environment were helocrene springs. Although they were the second most numerous taxonomical group in the springs, only two species were present there: Pisidium casertanum and P. personatum. The occurrence of both species strongly positively correlated with each other. Substrate type and a few chemical parameters were the main parameters, which differentiated the distribution of both species. While P. casertanum was found to be most abundant in vegetation, P. personatum preferred humolite substrate. The occurrence of P. casertanum was further influenced by nutrients compared to P. personatum, whose occurrence positively correlated with the common minerals. In general, biotope characteristics of springs were found to be more important for Pisidium species inhabiting oligotrophic mountain springs than water chemistry.