Cold mountain stream chironomids (Diptera) of the genus Diamesa indicate both historical and recent climate change.

Chironomids of the genus Diamesa (Meigen, 1835, Diptera: Chironomidae) inhabit cold, oxygen-rich running waters. We have investigated the presence of Diamesa and other freshwater macroinvertebrates at 22 stream sampling sites in 3 European high mountain regions (the Central Pyrenees, the Ötztal Alps, and the Tatra Mountains) to establish suitable temperature conditions for Diamesa dominance. It has been generally accepted that their high abundance was linked to the presence of glaciers; however, we have shown that in the Tatra Mountains, where there are no glaciers, the conditions for the dominance of Diamesa species are created due to permanent snowfields, the geographical orientation of the valley and shading by the surrounding high peaks. The historical connection of Diamesa to glaciers was investigated from the paleolimnological records of subfossil chironomid assemblages from the Bohemian Forest, where glaciers disappeared before or during the Late Glacial period. As expected, water temperature seems to be the main driver of Diamesa distribution, and we determined that the relative abundance of Diamesa species was significantly higher at the sites with a mean July water temperature below 6.5 °C. The Diamesa-dominated stream communities seems to be endangered due to ongoing climate warming and this assumption is supported by our paleolimnological results from the Bohemian Forest lakes, where Diamesa has disappeared due to warming of lake inflows at the beginning of the Holocene. These findings strengthen the former suggestions that some Diamesa species could be used as an indicator for tracking recent environmental changes in vulnerable ecosystems of cold mountain streams.

Tin(II) cations stabilized by non-symmetric N,N',O-chelating ligands: synthesis and stability.

A series of novel non-symmetric neutral N,N',O-chelating ligands derived from the α-iminopyridine 2-(C(R1)N(C6H3-2,6-iPr2))-6-(R2R3PO)C5H3N (L1: R1 = H, R2 = R3 = Ph; L2: R1 = Me, R2 = R3 = Ph; L3: R1 = H; R2 = Ph, R3 = EtO; L4: R1 = Me, R2 = Ph, R3 = EtO; L5: R1 = H, R2 = R3 = iPrO; L6: R1 = Me, R2 = R3 = iPrO) were synthesized. Ligands L1-6 were reacted with SnCl2 and Sn(OTf)2 with the aim of studying the influence of different R2R3PO functional groups on the Lewis base mediated ionization of SnCl2 and Sn(OTf)2. While all ligands L1-6 provided the corresponding ionic tin(II) complexes [L1-6 → SnCl]+[SnCl3]- (1-6), only ligands L1, L4 and L6 were able to stabilize tin(II) dications [L1,4,6 → Sn(H2O)][OTf]2 (7-9). The auto-ionized compounds [L3-6 → SnCl]+[SnCl3]- possessing ethylphenyl phosphinate and diisopropylphosphite substituents undergo elimination of EtCl and iPrCl, respectively, yielding compounds 10-13. These can either be interpreted as neutral tin(II)phosphinate chloride (10, 11) and tin(II)phosphonate chloride (12, 13), respectively, containing Sn-O and Sn-Cl bonds, and a PO → SnCl2 interaction, or as zwitterionic compounds, where the positive charge of the central tin atom is compensated by an [OSnCl2]- anion. Finally, DFT studies were performed to better understand the steric and electronic properties of the ligands L1-6 as well as the nature of the bonds in the resulting products, with a particular focus on complexes 10-13.

Understanding the Reactivity of Supported Late Transition Metals on a Bare Anatase (101) Surface: A Periodic Conceptual DFT Investigation.

The rapidly growing interest for new heterogeneous catalytic systems providing high atomic efficiency along with high stability and reactivity triggered an impressive progress in the field of single-atom catalysis. Nevertheless, unravelling the factors governing the interaction strength between the support and the adsorbed metal atoms remains a major challenge. Based on periodic density functional theory (DFT) calculations, this paper provides insight into the adsorption of single late transition metals on a defect-free anatase surface. The obtained adsorption energies fluctuate, with the exception of Pd, between -3.11 and -3.80 eV and are indicative of a strong interaction. Depending on the considered transition metal, we could attribute the strength of this interaction with the support to i) an electron transfer towards anatase (Ru, Rh, Ni), ii) s-d orbital hybridisation effects (Pt), or iii) a synergistic effect between both factors (Fe, Co, Os, Ir). The driving forces behind the adsorption were also found to be strongly related to Klechkowsky's rule for orbital filling. In contrast, the deviating behaviour of Pd is most likely associated with the lower dissociation enthalpy of the Pd-O bond. Additionally, the reactivity of these systems was evaluated using the Fermi weighted density of states approach. The resulting softness values can be clearly related to the electron configuration of the catalytic systems as well as with the net charge on the transition metal. Finally, these indices were used to construct a model that predicts the adsorption strength of CO on these anatase-supported d-metal atoms. The values obtained from this regression model show, within a 95 % probability interval, a correlation of 84 % with the explicitly calculated CO adsorption energies.

Influence of time-dependent sampling on fish plasma levels of select pharmaceuticals and per- and polyfluoroalkyl substances (PFASs).

Determining pharmaceutical levels in fish plasma represents an increasingly valuable approach for environmental assessments of pharmaceuticals. These fish plasma observations are compared to human therapeutic plasma doses because of the high evolutionary conservation of many drug targets among vertebrates. In the present study, we initially identified highly variable information regarding plasma sampling practices in the literature and then tested the hypothesis that fish plasma levels of selected pharmaceuticals and per- and polyfluoroalkyl substances (PFASs) would not change with time to process samples from the field. After common carp were placed in a wastewater-fed pond for one month, we immediately sampled fish plasma nonlethally in the field or after transferring fish to clean water and held them under these conditions for either 3 or 20 h. We then quantitated pharmaceuticals in water, and pharmaceuticals and PFASs in plasma by LC-MSMS. Whereas plasma levels of most pharmaceuticals decreased even after 3 h that fish spent in clean water, plasma concentrations of the PFASs examined here remained stable over 20 h. Collectively, our examination of these time-dependent sampling approaches and associated findings highlight the importance of appropriate and consistent sampling for bioaccumulation studies, biomonitoring activities, and aquaculture product safety evaluations.

Reactivity of a N-Coordinated Germylene-Borane Complex: From Ge→B to Ge→Ga Coordination.

Reactivity studies of the GeII →B complex L(Cl)Ge⋅BH3 (1; L=2-Et2 NCH2 -4,6-tBu2 -C6 H2 ) were performed to determine the effect on the GeII →B donation. N-coordinated compounds L(OtBu)Ge⋅BH3 (2) and [LGe⋅BH3 ]2 (3) were prepared. The possible tuning of the GeII →B interaction was proved experimentally, yielding compounds 1-PPh2 -8-(LGe)-C10 H6 (4) and L(Cl)Ge⋅GaCl3 (5) without a GeII →B interaction. In 5, an unprecedented GeII →Ga coordination was revealed. The experimental results were complemented by a theoretical study focusing on the bonding in 1-5. The different strength of the GeII →E (E=B, Ga) donation was evaluated by using energy decomposition analysis. The basicity of different L(X)Ge groups through proton affinity is also assessed.

Water reuse for aquaculture: Comparative removal efficacy and aquatic hazard reduction of pharmaceuticals by a pond treatment system during a one year study.

Aquaculture is increasing at the global scale, and beneficial reuse of wastewater is becoming crucial in some regions. Here we selected a unique tertiary treatment system for study over a one-year period. This experimental ecosystem-based approach to effluent management included a treated wastewater pond (TWP), which receives 100% effluent from a wastewater treatment plant, and an aquaculture pond (AP) that receives treated water from the TWP for fish production. We examined the fate of a wide range of pharmaceutically active compounds (PhACs) in this TWP-AP system and a control pond fed by river water using traditional grab sampling and passive samplers. We then employed probabilistic approaches to examine exposure hazards. Telmisartan, carbamazepine, diclofenac and venlafaxine, exceeded ecotoxicological predicted no effect concentrations in influent wastewater to the TWP, but these water quality hazards were consistently reduced following treatment in the TWP-AP system. In addition, both grab and passive sampling approaches resulted in similar occurrence patterns of studied compounds, which highlights the potential of POCIS use for water monitoring. Based on the approach taken here, the TWP-AP system appears useful as a tertiary treatment step to reduce PhACs and decrease ecotoxicological and antibiotic resistance water quality hazards prior to beneficial reuse in aquaculture.

Sn,P-coordinated Ru cation: a robust catalyst for aerobic oxidations of benzylamine and benzyl alcohol.

A stable ionic κ2Sn,P-coordinated Ru complex shows excellent catalytic activity in aerobic oxidations of benzylamine and benzyl alcohol. This complex is stabilized by a stannylene-phosphine peri-substituted naphthalene ligand, which can act as either a reducing agent for a Ru(III) complex or as a κ2Sn,P-chelating ligand for Ru(II) compounds.

N-Donor stabilized tin(II) cations as efficient ROP catalysts for the synthesis of linear and star-shaped PLAs via the activated monomer mechanism.

α-Iminopyridine ligands L1 (2-(CHN(C6H2-2,4,6-Ph3))C5H4N), L2 (2-(CHN(C6H2-2,4,6-tBu3))C5H4N) and L3 (1,2-(C5H4N-2-CHN)2CH2CH2) differing by the steric demand of the substituent on the imine CHN group and by the number of donating nitrogen atoms were utilized to initiate a Lewis base mediated ionization of SnCl2 in an effort to prepare ionic tin(II) species [L1-3 → SnCl][SnCl3]. The reaction of L1 and L2 with SnCl2 led to the formation of neutral adducts [L1 → SnCl2] (2) and [L2 → SnCl2] (3). The preparation of the desired ionic compounds was achieved by subsequent reactions of 2 and 3 with an equivalent of SnCl2 or GaCl3. In contrast, ligand L3 containing four donor nitrogen atoms showed the ability to ionize SnCl2 and also Sn(OTf)2, yielding [L3 → SnCl][SnCl3] (7) and [L3 → Sn(H2O)][OTf]2 (8). The study thus revealed that the reaction is dependent on the type of the ligand. The prepared complexes 4-8 together with the previously reported [{2-((CH3)CN(C6H3-2,6-iPr2))-6-CH3O-C5H3N}SnCl][SnCl3] (1) were tested as catalysts for the ROP of L-lactide, which could operate via an activated monomer mechanism. Finally, a DFT computational study was performed to evaluate the steric and electronic properties of the ionic tin(II) species 1 and 4-8 together with their ability to interact with the L-lactide monomer.

Reactivity of Single Transition Metal Atoms on a Hydroxylated Amorphous Silica Surface: A Periodic Conceptual DFT Investigation.

The drive to develop maximal atom-efficient catalysts coupled to the continuous striving for more sustainable reactions has led to an ever-increasing interest in single-atom catalysis. Based on a periodic conceptual density functional theory (cDFT) approach, fundamental insights into the reactivity and adsorption of single late transition metal atoms supported on a fully hydroxylated amorphous silica surface have been acquired. In particular, this investigation revealed that the influence of van der Waals dispersion forces is especially significant for a silver (98 %) or gold (78 %) atom, whereas the oxophilicity of the Group 8-10 transition metals plays a major role in the interaction strength of these atoms on the irreducible SiO2 support. The adsorption energies for the less-electronegative row 4 elements (Fe, Co, Ni) ranged from -1.40 to -1.92 eV, whereas for the heavier row 5 and 6 metals, with the exception of Pd, these values are between -2.20 and -2.92 eV. The deviating behavior of Pd can be attributed to a fully filled d-shell and, hence, the absence of the hybridization effects. Through a systematic analysis of cDFT descriptors determined by using three different theoretical schemes, the Fermi weighted density of states approach was identified as the most suitable for describing the reactivity of the studied systems. The main advantage of this scheme is the fact that it is not influenced by fictitious Coulomb interactions between successive, charged reciprocal cells. Moreover, the contribution of the energy levels to the reactivity is simultaneously scaled based on their position relative to the Fermi level. Finally, the obtained Fermi weighted density of states reactivity trends show a good agreement with the chemical characteristics of the investigated metal atoms as well as the experimental data.

Spatial distribution of native fish species in tributaries is altered by the dispersal of non-native species from reservoirs.

Reservoirs are known to alter temperature and flow regimes, shift nutrient cycles, reduce downstream species diversity and enable a predominantly upstream spread of non-native species. However, information about the seasonal dynamics of the spread of non-natives from a reservoir to its tributaries and the further consequences regarding the spatial distribution of native species is rare. We observed the occurrence of fish in the Vltava River and its tributaries (Elbe catchment area, central Europe) upstream of the Lipno Reservoir for five consecutive years. We radio-tagged two non-native and four native species. To detect assemblage spatial variability, we sampled sites in the study area by electrofishing twice per year (spring and autumn). We expected seasonal trends in non-native species appearance in upstream reservoir tributaries and, conversely, low motivation of native fishes to descend to the reservoir. By analysing nearly 3000 individuals of 21 species from the longitudinal profile of the study area, we observed an effect of reservoir distance on the native species ratio in the upper Vltava catchment area, i.e., an increase in distance increased the native species proportion, and the opposite was observed for non-native species. Analyses of 3798 tracking positions of 193 tagged individuals showed massive spring dispersal of non-native species from the reservoir to the main tributary, the Vltava River, and their return to the reservoir for wintering. Their upstream movement positively correlated with an increase in flow rate. Native Salmo trutta showed a specific shift from the Vltava River to smaller streams during the summer, when the presence of non-native species in the Vltava River was most significant. These findings indicate that non-native species repeatedly spread from the reservoir to the upstream river stretch and its tributaries and potentially compete with native species for resources.

De facto reuse at the watershed scale: Seasonal changes, population contributions, instream flows and water quality hazards of human pharmaceuticals.

With increasing population growth and climate change, de facto reuse practices are predicted to increase globally. We investigated a longitudinal gradient within the Uhlava River, a representative watershed, where de facto reuse is actively occurring, during Fall and Spring seasons when instream flows vary. We observed human pharmaceutical levels in the river to continuously increase from the mountainous areas upstream to downstream locations and a potable intake location, with the highest concentrations found in small tributaries. Significant relationship was identified between mass flow of pharmaceuticals and the size of human populations contributing to wastewater treatment plant discharges. Advanced ozonation and granular activated carbon filtration effectively removed pharmaceuticals from potable source waters. We observed a higher probability of encountering a number of targeted pharmaceuticals during colder Spring months when stream flows were elevated compared to warmer conditions with lower flows in the Fall despite a dilution paradigm routinely applied for surface water quality assessment and management efforts. Such observations translated to greater water quality hazards during these higher Spring flows. Future water monitoring efforts should account for periods when higher chemical uses occur, particularly in the face of climate change for regions experiencing population growth and de facto reuse.

Changes in microclimate and hydrology in an unmanaged mountain forest catchment after insect-induced tree dieback.

Hydrological and microclimatic changes after insect-induced tree dieback were evaluated in an unmanaged central European mountain (Plesné, PL) forest and compared to climate-related changes in a similar, but almost intact (Certovo, CT) control forest during two decades. From 2004 to 2008, 93% of Norway spruce trees were killed by a bark beetle outbreak, and the entire PL area was left to subsequent natural development. We observed that (1) climate-related increases in daily mean air temperature (2 m above ground) were 1.6 and 0.5 °C on an annual and growing season basis, respectively, and an increase in daily mean soil temperature (5 cm below ground) was 0.9 °C during growing seasons at the CT control from 2004 to 2017; (2) daily mean soil and air temperatures increased by 0.7-1.2 °C on average more at the disturbed PL plots than in the healthy forest; (3) water input to soils increased by 20% but decreased by 17% at elevations of 1122 and 1334 m, respectively, due to decreased occult deposition to, and evaporation from, canopies after tree dieback; (4) soil moisture was 5% higher on average (but up to 17% higher in dry summer months) in the upper PL soil horizons for 5-6 years following the tree dieback; (5) run-off from the PL forest ~6% (~70 mm yr-1) increased relatively to the CT forest (but without extreme peak flows and erosion events) after tree dieback due to the ceased transpiration of dead trees and elevated water input to soils; and (6) relative air humidity was 4% lower on average at disturbed plots than beneath living trees. The rapid tree regeneration during the decade following tree dieback resulted in a complete recovery in soil moisture, a slow recovery of discharge and air humidity, but a still insignificant recovery in air and soil temperatures.

Organogermanium(II) Hydrides as a Source of Highly Soluble LiH.

The reactions of monomeric C,N-chelated organogermanium(II) hydride L(H)Ge⋅BH3 with organolithium salts RLi yielded lithium hydrogermanatoborates (Li(THF)2 {BH3 [L(H)GeR]})2 . Compound (Li(THF)2 {BH3 [L(H)GePh]})2 was used as a source of LiH for the reduction of organic C=O or C=N bonds in nonpolar solvents accompanied by the elimination of a neutral complex L(Ph)Ge⋅BH3 . The interaction of (Li(THF)2 {BH3 [L(H)GePh]})2 with the polar C=O bond was further investigated by computational studies revealing a plausible geometry of a pre-reactive intermediate. The experimental and theoretical studies suggest that, although the Li atom of (Li(THF)2 {BH3 [L(H)GePh]})2 coordinates the C=O bond, the GeH fragment is the active species in the reduction reaction. Finally, benzaldehyde was reduced by a mixture of L(H)Ge⋅BH3 with PhLi in nonpolar solvents.

Psychoactive pharmaceuticals in aquatic systems: A comparative assessment of environmental monitoring approaches for water and fish.

Environmental monitoring and surveillance studies of pharmaceuticals routinely examine occurrence of substances without current information on human consumption patterns. We selected 10 streams with diverse annual flows and differentially influenced by population densities to examine surface water occurrence and fish accumulation of select psychoactive medicines, for which consumption is increasing in the Czech Republic. We then tested whether passive sampling can provide a useful surrogate for exposure to these substances through grab sampling, body burdens of young of year fish, and tissue specific accumulation of these psychoactive contaminants. We identified a statistically significant (p < 0.05) relationship between ambient grab samples and passive samplers in these streams when psychoactive contaminants were commonly quantitated by targeted liquid chromatography with tandem mass spectrometry, though we did not observe relationships between passive samplers and tissue specific pharmaceutical accumulation. We further observed smaller lotic systems with elevated contamination when municipal effluent discharges from more highly populated cities contributed a greater extent of instream flows. These findings identify the importance of understanding age and species specific differences in fish uptake, internal disposition, metabolism and elimination of psychoactive drugs across surface water quality gradients.

Hetero Diels-Alder Reactions of Masked Dienes Containing Heavy Group†15 Elements.

Treatment of N,C,N-chelated organopnictogen(I) compounds ArE (1-3) (Ar=2,6-(RN=CH)2 C6 H3 , E/R=As/Dmp (1), Sb/tBu (2), and Bi/tBu (3), where Dmp=2,6-Me2 C6 H3 ) with various electron-deficient alkynes RC≡CR' (R/R'=CO2 Me (DMAD), R/R'=H/CO2 Me, or R/R'=NC5 F4 ) affords different types of heterocyclic compounds. In these reactions, 1-3 act as hidden dienes and participate in hetero-Diels-Alder (DA) reactions, a feature that has been only rarely reported for heavier pnictogen compounds. In this way, reactions of 1 furnished the set of 1-arsanaphthalenes 4-6. The most likely mechanism involves two steps, that is, an arsa-DA reaction giving a 1-arsa-1,4-dihydro-iminonaphthalene, followed by CH→NH proton migration. In contrast, this reaction sequence terminates at the first step in the case of the antimony analogue 2, thus giving the 1-stiba-1,4-dihydro-iminonaphthalenes 7 and 8. Reactions of the bismuth congener 3 gave one of two products depending on the alkyne used. Reaction of 3 with DMAD gave 1-bisma-1,4-dihydro-iminonaphthalene 9, whilst its reaction with two equivalents of HC≡C(CO2 Me) gave bismacyclohexadiene (10). All compounds have been characterized by NMR, IR, and Raman spectroscopies and X-ray diffraction analysis. The experimental data were complemented by a computational study, including a description of the reaction profiles of the hetero-DA reactions and an assessment of the aromaticities of the heterocyclic naphthalene derivatives.

From a 2,1-Benzazaarsole to Elusive 1-Arsanaphthalenes in One Step.

The 2,1-benzazaarsole (1) showed a diene-like reactivity towards selected alkynes RC≡CR (R=CO2 Me, C5 F4 N) thus forming 1-arsa-1,4-dihydro-iminonaphthalenes 2 a and 3 a as hardly isolable intermediates, that underwent facile CH→NH proton migration leading to before elusive substituted 1-arsanaphthalenes 2 b and 3 b that could be completely structurally characterized.

Correction to: Effects of multi-component mixtures from sewage treatment plant effluent on common carp (Cyprinus carpio) under fully realistic condition.

The original version of this Article unfortunately contained an error. The authors' given and family names were transposed erroneously. It has been corrected now in this Erratum.

Effects of Multi-Component Mixtures from Sewage Treatment Plant Effluent on Common Carp (Cyprinus carpio) under Fully Realistic Condition.

This study characterized changes in biomarker responses in common carp (Cyprinus carpio) upon exposure to effluent water discharged from a sewage treatment plant (STP) under real conditions. Fish were exposed to contamination in Cezarka pond, which receives all of its water input from the STP in the town of Vodnany, Czech Republic. Five sampling events were performed at day 0, 30, 90, 180, and 360 starting in April 2015. In total, 62 pharmaceutical and personal care products (PPCPs) were detected in the polar organic chemical integrative sampler. Compared to a control pond, the total concentration of PPCPs was 45, 16, 7, and 7 times higher in Cezarka pond at day 30, 90, 180, and 360, respectively. The result of oxidative stress and antioxidant enzyme biomarkers indicated alterations in the liver and intestine tissues of fish from Cezarka pond at day 30 and 360, respectively. High plasma vitellogenin levels were observed in both exposed females (180 and 360 days) and males (360 days) compared with their respective controls. However, only exposed female fish had higher vitellogenin mRNA expression than the control fish in these periods. Exposed female fish showed irregular structure of the ovary with scattered oocytes, which further developed to a vitellogenic stage at day 360. Low white blood cell levels were indicated in all exposed fish. Despite numerous alterations in exposed fish, favorable ecological conditions including high availability of food resulted in a better overall condition of the exposed fish after 1 year of exposure compared to the controls.

Heavier pnictinidene gold(i) complexes.

N,C,N-Chelated pnictinidenes ArE [where E = As, Sb or Bi; Ar = 2,6-(tBuN[double bond, length as m-dash]CH)2C6H3] were used as ligands for the coordination of various gold(i) complexes. Thus, the reaction of ArE with [AuCl(Me2S)] gave complexes [AuCl(ArE)] [where E = As (1) or Sb (2)] that exhibited only limited stability in solution. By contrast, the reaction of ArBi with [AuCl(Me2S)] led to the immediate deposition of gold metal and the oxidation of the bismuth atom giving ArBiCl2. The treatment of a tetrameric gold alkynyl complex [Au(C[triple bond, length as m-dash]CPh)]4 with ArAs and ArSb gave ionic compounds [Au(ArAs)2]+[Au2(C[triple bond, length as m-dash]CPh)3]- [denoted as 3+[Au2(C[triple bond, length as m-dash]CPh)3]-] and [Au(ArSb)2]+[Au(C[triple bond, length as m-dash]CPh)2]- [denoted as 4+[Au(C[triple bond, length as m-dash]CPh)2]-], respectively. Finally, the reaction of ArE with the carbene gold(i) complex [Au(IPr)(MeCN)]+[BF4]- [where IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, MeCN = acetonitrile] produced ionic complexes [Au(IPr)(ArE)]+[BF4]- [for cations: E = As (5+), Sb (6+) or Bi (7+)]. All complexes were characterized using 1H and 13C NMR, high mass accuracy electrospray ionization mass spectrometry (ESI-MS), IR and Raman spectroscopy and (except for 1) by single-crystal X-ray diffraction analysis. Furthermore, the structure and bonding of both neutral and ionic complexes with different coordination patterns have also been investigated in detail using a Density Functional Theory (DFT) computational approach.

Complex effects of pollution on fish in major rivers in the Czech Republic.

Monitoring the contamination level in aquatic environments and assessing the impact on aquatic life occurs throughout the world. In the present study, an approach based on a combination of biomarkers and the distribution of various industrial and municipal pollutants was used to investigate the effect of aquatic environmental contamination on fish. Monitoring was performed in ten rivers in the Czech Republic (Berounka, Dyje, Elbe, Luznice, Odra, Ohre, Otava, Sázava, Svratka, and Vltava rivers, with one or two locations in each river) at the same sites that were regularly monitored within the Czech National Monitoring Program in 2007-2011. Health status, hepatic ethoxyresorufin-O-deethylase (EROD) activity, total cytochrome P450 content, and the plasma vitellogenin concentration were assessed in wild chub (Squalius cephalus) males caught at the monitored sites. The contamination level was the highest in the Svratka River downstream of Brno. Among all measured persistent organic pollutants (POPs), polychlorinated biphenyls and dichlorodiphenyltrichloroethane and its metabolites were the major contributors of POPs in fish muscle. Elbe, Odra, and Svratka rivers were identified as the most polluted. Fish from these locations showed reduced gonad size, increased vitellogenin concentration in male plasma, EROD, and total cytochrome P450 content. These biomarkers can be used for future environmental monitoring assessments. Overall, this study improves our understanding of the relationship between human activities and pollutant loads and further contributes to the decision to support local watershed managers to protect water quality in this region.