Unio Tumidus Research Articles

Biochemical responses of bivalve mollusk Unio tumidus to the effect of nanoform of zinc oxide depending on the thermal regime

Indigenous bivalve mollusks from the cooling reservoirs of thermoelectric power plants (TPPs) are subjected to constantly elevated temperature and industrial pollution. Therefore, they could be regarded as a suitable model organisms adapted to the combination of typical novel environmental challengers in their habitats. The aim of this study was to elucidate the bioavailability of novel pollutant – nanoform of Zinc oxide (nZnO) – in the mollusks from TPPs depending on the temperature of exposure. The metal accumulation and molecular responses of stress were investigated in the Unio tumidus (Unionidae) mollusks from two cooling reservoirs of TPPs (D- and B-groups) under the exposures to Zinc ions (3.1 µM), nZnO (3.1 µM) at 18 °C, elevated temperature (25 °C), and nZnO at 25 °C during 14 days. In most of the experimental groups, a selective increase of metal accumulation in metallothioneins in comparison with the tissue level, up-regulation of cytochrome c level, and the decrease of oxyradical gene­ration were detected in the digestive gland. In the gills, the increased DNA fragmentation was found. Under the 25 °C, the level of glutathione in the tissues was depleted. B-groups were distinguished by down-regulation of cholinesterase activity and increased level of cadmium in tissues. Thus, the biochemical responses of mussels from the cooling reservoirs reflect the lack of specific mechanisms of detoxification and preva­lence of the nonspecific responses of stress. In the BPP-groups, the signs of toxicity indicate higher level of pollution in the reservoir.

Multi-marker study of the response of bivalve mollusk Unio tumidus induced by the compounds of typical municipal effluents

The pharmaceutical and personal care products (PPCPs) became the most typical pollutants of the surface waters. The aim of this study was to evaluate the effects of the combine exposure to the common compounds of the municipal effluents, constituent of plastics bisphenol A (BPA) and popular medicine nifedipine (Nfd), on the model organism, a mussel Unio tumidus. Male U. tumidus were exposed for 14 days to the combination of Nfd (10 μM) and BPA (0.88 nM). The indices of oxidative stress, metabolic, immune and endocrine activity, metal balance, as well as the manifestations of toxicity were detected. The exposure caused the features known for the effect of Nfd: the activation of the oxidative stress response, particularly Cu,Zn-superoxide dismutase (by 6.0 times), glutathione and oxyradical levels, metabolic shift to the anaerobiosis due to the elevated level of lactate in the digestive gland. The manifestation of endocrine disruption typical for the BPA effect - the increased level of alkali-labile phosphates (vitellogenin-like proteins) in gonads was detected. The caspase-3 related apoptotic activity was suppressed; whereas the cathepsin D mediated proteolysis and immune response of phenoloxidase were up-regulated significantly. The signs of geno-, neuro- and cytotoxicity were detected. These results detect that the approximation of the experimental conditions to the environmentally realistic situation could assist the comprehensive forecasting of the effects of utilized PPCPs for the aquatic animals. Keywords: bisphenol A, nifedipine, combine exposure, endocrine disruption, oxidative stress, bivalve mollusk.

A field study of hemolymph yolk protein levels in a bivalve (Unio tumidus) and future considerations for bivalve yolk protein as endocrine biomarker

Induction of yolk protein in male fish is a recognized biomarker for estrogenic exposure because the estrogen-dependent induction mechanism is well investigated and there is a clear difference in yolk protein levels of unexposed males and females. Attempts have been made to use induction of bivalve yolk protein as biomarker for estrogenic exposure. However, several biomarker validation criteria have not yet been investigated e.g. an in-depth understanding of the induction mechanism and background variability is needed and reliable detection assays are yet to be developed.To obtain background knowledge about yolk protein levels freshwater bivalves (Unio tumidus) were collected in an uncontaminated Danish lake over the course of a year (33 collection dates). The hemolymph yolk protein concentration of 569 individuals was determined by a species specific enzyme-linked immunosorbent assay (ELISA) and male and female gonadal development cycles were established. The average yolk protein levels of males and females collected at each sampling date overlapped in some periods; the male and female range was 66,946 - 169,692 ng/mL and 88,731 - 681,667 ng/mL, respectively. Because male and female hemolymph yolk protein levels overlap, great care should be taken if yolk protein induction in bivalve hemolymph is considered as endocrine biomarker.

A massive freshwater mussel bed (Bivalvia: Unionidae) in a small river in Ukraine

During a monitoring survey, a massive mussel bed was found and studied in the Gnily Rig River, Ukraine. The mussel bed was 25 cm thick and multilayered, with one of the greatest densities and biomass (wet weight) recorded so far in natural aggregations: up to 1,801.0 ± 175.4 ind./m2 and up to 88.3 ± 20.7 kg/m2, respectively. The site was surveyed periodically since 2009, and despite the temporal differences in the density (but not in biomass) the mussel bed was stable and should be considered for protection due to its high ecological and conservational value. key words: Unionoida, Unio tumidus, U. pictorum, Anodonta anatina, freshwater mussels, densities, conservation

Flooding modifies the genotoxic effects of pollution on a worm, a mussel and two fish species from the Sava River

Extreme hydrological events, such as water scarcity and flooding, can modify the effect of other stressors present in aquatic environment, which could result in the significant changes in the ecosystem functioning. Presence and interaction of various stressors (genotoxic pollutants) in the environment can influence the integrity of DNA molecules in aquatic organisms which can be negatively reflected on the individual, population and community levels. Therefore, in this study we have investigated the impact of flooding, in terms of genotoxicity, on organisms belonging to different trophic levels. The study was carried out on the site situated in the lower stretch of the Sava River which faced devastating effects of severe flooding in May 2014. The flooding occurred during our field experiment and this event provided a unique opportunity to assess its influence to the environment. The in situ effects of this specific situation were monitored by measuring physical, chemical and microbiological parameters of water, and by comparing the level of DNA damage in coelomocytes and haemocytes of freshwater worms Branchiura sowerbyi, haemocytes of freshwater mussels Unio tumidus and blood cells of freshwater fish Abramis bjoerkna/Abramis sapa, by means of the comet assay. Our study indicated that the flooding had a significant impact on water quality by decreasing the amount and discharge rate of urban wastewaters but simultaneously introducing contaminants from the nearby fly ash disposal field into river by runoff, which had diverse effects on the level of DNA damage in the studied organisms. This indicates that the assessment of genotoxic pollution in situ is strongly affected by the choice of the bioindicator organism.

The effects of zinc nanooxide on cellular stress responses of the freshwater mussels Unio tumidus are modulated by elevated temperature and organic pollutants

Nanoparticle toxicity is a growing concern in freshwater habitats. However, understanding of the nanoparticle effects on aquatic organisms is impeded by the lack of the studies of the nanoparticles effects in the environmentally relevant context of multiple stress exposures. Zinc oxide nanoparticles (n-ZnO) are widely used metal-based nanoparticles in electronics and personal care products that accumulate in aquatic environments from multiple non-point sources. In this study, we evaluated the effects of n-ZnO in a model organism, a mussel Unio tumidus, and the potential modulation of these effects by common co-occurring environmental stressors. Male U. tumidus were exposed for 14 days to n-ZnO (3.1μM), Zn2+ (3.1μM), Ca-channel blocker nifedipine (Nfd 10μM), combinations of n-ZnO and Nfd or n-ZnO and thiocarbamate fungicide Tattoo (Ta, 91μgL−1) at 18°C, and n-ZnO at 25°C (n-ZnO+t°). Total and metallothionein-bound Zn levels as well as levels of metallothioneins (MT), cellular stress responses and cytotoxicity biomarkers were assessed in the mussels. The key biomarkers that showed differential responses to different single and combined stressors in this study were activities of caspase-3 and lysosomal cathepsin D, as well as protein carbonyl content. At 18°C, exposures to n-ZnO, organic pollutants and their combinations led to a prominent up-regulation of MT levels (by ∼30%) and oxidative stress response including up-regulation of superoxide dismutase activity, an increase in oxyradical production, and a 2–3-fold decrease in the levels of protein carbonyls in all exposures except nZnO+Ta. Expos ure to n-ZnO in the absence of other stressors also led to a strong (∼7-fold) elevation of cathepsin D activity. Cellular responses to Zn2+ and n-ZnO were different indicating that n-ZnO was not due exclusively to Zn release. Ca-channel blocker Nfd affected intracellular Zn distribution (reflected in the prominent elevation of Zn-MT levels) and caused reductive stress indicated by elevated levels of reduced glutathione levels and an increase in lactate/pyruvate ratio (reflecting higher NADH/NAD ratio). Elevated temperature (25°C) abolished most of the typical responses to n-ZnO and induced oxidative injury, DNA fragmentation and caspase-3 mediated apoptosis in n-ZnO-exposed mussels. DNA fragmentation was also induced by exposure to organic toxins (alone and in combination with n-ZnO) but not by n-ZnO alone. These data indicate that n-ZnO toxicity to freshwater organisms is modulated by organic pollutants and enhanced by elevated temperatures.

Вплив побутових забруднювачів на стан металотіонеїнів у тканинах двостулкового молюска Unio tumidus

Personal care products and pharmaceuticals are the most common novel water pollutants, and it is difficult to predict the effects. It is expected that they can modulate the activity of molecular detoxification systems. Since the production of the metal-binding proteins, metallothioneins (MTs) are activated by a wide range of stress factors, the aim of the study was to compare the functional characteristics of the MTs from digestive gland (DG) of male bivalve mollusc Unio tumidus from reference pond, polluted by sewage effluents pond and after the exposure to widespread water personal care pollutants ibuprofen (I, 250 ng / L), triclosan (T, 500 ng / L) or estrone (E1, 100 ng / L) for 14 days (overall term of staying in the laboratory aquaria – 21 days). The elevation of the content of zinc, copper and cadmium in bivalves’ tissues of DG, gonads and MTs as well as total level of MTs was noted in polluted pond compared to the reference one. Exposure factors and chronic pollution caused an increase of level of Zn-binding MT form on a background of reduced (I-, T-group) or increased (E1 group) total protein content of MTs and constant total level of zinc and copper in tissue. Under the effect of I, T and E1, marked decreasing in copper level and increasing (in 2.2–3 times) in zinc level were observed in the gonads. Thus, we should assume that the elevation of the content of zinc-MT in the bivalves DG can be considerded as the compound of the unspecific supporting strategy of the signa­ling function of these ions under the harmful efects. Keywords : bivalve mollusc, ibuprofen, triclosan, estron, metallothioneins, zinc.

Status of Markers of the Aquatic Environment Toxicity in Bivalve Mollusk Unio tumidus under impact of Common Municipal Pollutants

Status of Markers of the Aquatic Environment Toxicity in Bivalve Mollusk Unio tumidus under impact of Common Municipal Pollutants

Human waterborne protozoan parasites in freshwater bivalves (Anodonta anatina and Unio tumidus) as potential indicators of fecal pollution in urban reservoir

The presence of environmentally robust dispersive stages of intestinal protozoan parasites in waters represents an important public health threat since these pathogens have caused numerous outbreaks related to either drinking or recreational waters. The purpose of this study was to evaluate the presence of Cryptosporidium oocysts, Giardia and Blastocystis cysts, and microsporidian spores in mussels collected from municipal reservoir, Lake Malta (Poland, Europe). Two species of freshwater bivalves ( Anodonta anatina and Unio tumidus ) were tested for the enteropathogens. A direct wet smear and smears stained with chromotrope 2R, Ziehl–Neelsen and iron hematoxylin made from each pellet of the hemolymph, gills and gastrointestinal homogenates of mussels were examined microscopically. In the study the immunofluorescence antibody test kit MERIFLUOR Cryptosporidium/Giardia was also used for all bivalve samples. None of investigated parasites were found in U. tumidus . In A. anatina , Cryptosporidium oocysts and Blastocystis cysts were detected in 15.4 and 5.1% of mussel samples, respectively. The present results indicate contamination of Lake Malta with Cryptosporidium and Blastocystis , which is important from the point of view of public health threats because of different human uses of studied reservoir.

Long-term changes in the occurrence of unionid bivalves in a eutrophic lake

Earlier studies (1972–1987) on the occurrence of unionid bivalves in the eutrophicated Lake Mikolajskie (Masurian Lakeland, NE. Poland) were continued in 1992–2008. Of the five recorded species (Unio tumidus, U. pictorum, Anodonta cygnea, A. anatina, and Pseudanodonta complanata), A. cygnea and P. complanata disappeared by 1987, whereas U. pictorum was observed sporadically at that time, and the unionid occurrence zone was markedly reduced. Beginning in 1992, a pronounced increase in abundance of U. tumidus was observed, and since 2002–2003, a decline of the other two species. Since 2003 the maximal original vertical distribution of U. tumidus (down to ca. 5 m) was re-established. The size and age structure of its population changed markedly during the study. No individuals of shell length exceeding 55 mm and aged more than 5–6 years were recorded since 1987. Between 1972 and 1987 one-year-old individuals prevailed, whereas in the following years the age structure changed slowly, and in 2008 twoto four-yearold bivalves were most frequent. The potential effects of changes in trophy and the effects of other factors, e.g. decline of Dreissena polymorpha, on changes in the occurrence of Unionidae in Lake Mikolajskie are discussed.

Evaluation of yolk protein levels as estrogenic biomarker in bivalves; comparison of the alkali-labile phosphate method (ALP) and a species-specific immunoassay (ELISA)

Altered concentration of the vertebrate yolk protein precursor vitellogenin is a recognized biomarker for endocrine disruption in fish, and within recent years yolk protein alteration has also been associated with endocrine disruption in bivalves. Species-specific, direct and sensitive methods for quantification of vitellogenin in fish have been available for years whereas bivalve yolk protein levels have been estimated indirectly by alkali-labile phosphate (ALP) liberated from high molecular weight proteins because the sequence and biochemical structure of most bivalve yolk proteins are unknown. By applying a species-specific enzyme-linked immunosorbent assay (ELISA) for accurate determination of yolk protein level the impact of 17β-estradiol (57, 164 and 512ng/L) on the freshwater bivalve Unio tumidus was investigated and compared with ALP estimations. Seven weeks of exposure during the pre-spawning and spawning period had no consistent effect on yolk protein concentration in hemolymph, and ALP levels in hemolymph also remained unchanged in both males and females. Further, basal male and female ALP levels were indistinguishable whereas the ELISA demonstrated that yolk protein levels of females exceeded male levels at the time of sampling, although male basal levels were high compared to fish. Altogether it is shown that individual ALP levels do not reflect yolk protein levels and hence hemolymph ALP levels cannot serve as biomarker for estrogenic exposure during the pre-spawning and spawning period in U. tumidus. The necessity of sensitive and validated biomarkers for reliable interpretation of data and the utility of ALP and yolk protein levels as biomarkers in bivalves are discussed.

Empty native and invasive bivalve shells as benthic habitat modifiers in a large river

Bivalves are remarkable ecosystem engineers and their long-lasting shells may provide important physical structures for benthic organisms. In the last decades the Danube River has experienced great changes in the bivalve fauna, i.e. several native species have been declining and several invasive species have been introduced. The invasive Corbicula fluminea and Sinanodonta woodiana are now widespread and produce large amounts of shells. In this study, we investigated empty shells of native (Anodonta anatina, Unio tumidus) and invasive (C. fluminea, S. woodiana) bivalves (including their mixtures) as benthic substrates and compared them to clay granules (control), which mimics the natural hard substrates in the Danube River (Hungary). Macroinvertebrate colonization was compared between (i) empty shells and control substrate; (ii) different bivalve species (native and invasive) and (iii) three scenarios (before invasion, and short and long time after invasion) by using a mix of empty shells (native, native plus invasive, and invasive species). In comparison to control treatments the empty shells facilitated the presence of amphipods, caddis larvae and isopods, which contributed to a shift in the trophic structure by decreasing the proportion of gathering collectors while increasing the presence of shredders and predators. Several shell traits such as size, outer-shell surface roughness, hardness, thickness, 3D shape and chemical composition may be important attributes in the habitat modifying effects; however, this study could not disentangle which contribute most for the differences found. Given the capability of invasive C. fluminea and S. woodiana to accumulate large amounts of empty shells on several sites of the Danube, its habitat modifying effects can be particularly important, especially on the macroinvertebrate community structure. Moreover, these effects may increase in near future due to the predicted more frequent and severe extreme climatic conditions, which have been responsible for massive mortalities in both species.

The impact of in vivo and in vitro exposure to base analogue 5-FU on the level of DNA damage in haemocytes of freshwater mussels Unio pictorum and Unio tumidus

The impact of in vivo and in vitro exposure to anticancer drug 5-Fluorouracil (5-FU) on the level of DNA damage was evaluated using comet assay on haemocytes of freshwater mussels Unio pictorum and Unio tumidus. For the in vivo experiment, the groups of 5 mussels per concentration were exposed for 72 h to 5-FU (0.04, 0.4, 4, 40 and 100 μM) with 0.4 μM being the lowest concentration to induce significant DNA damage. For the in vitro experiment, the primary cultures of haemocytes were treated with 0.04, 0.4, 4 and 40 μM 5-FU for 22 h and the treatment with CdCl2 was used as a positive control. In contrast to in vivo exposure, 5-FU did not induce significant increase of DNA damage in vitro, possibly because of the absence of haemocytes proliferation in primary cultures.

Diversity of the molecular responses to separate wastewater effluents in freshwater mussels

The environmental safety of pharmaceutical and personal care products (PPCPs) requires a crucial examination. The aim of this study was to evaluate the responses of biomarkers of stress and toxicity in freshwater mussels to the effect of commonly found PPCPs in wastewater. We treated male mussels Unio tumidus, from an undisturbed site with ibuprofen (IBU, 250ngL−1), triclosan (TCS, 500ngL−1), or estrone (E1, 100ngL−1) for 14days. Untreated mussels from this site (C) and mussels inhabiting a polluted area (P) were also examined after a similar time of being kept in the laboratory. The consequences of chronic exposure of the mussels in the P-group were reflected in elevated concentrations of oxyradicals (1.4 times), oxidized glutathione (4.3 times), lipofuscin (2.2 times), and DNA-strand breaks in the digestive gland (DG) in comparison to the C-group, higher levels of caspase-3 activity in the DG, and vitellogenin-like proteins in gonads among all studied groups. Exposed mussels demonstrated some common responses with mussels in the P-group: elevated levels of lactate/pyruvate ratio, lipofuscin (IBU and E1), DNA fragmentation (TCS and E1), and caspase-3 activity (TCS and E1). Exposed to PPCPs mussels also showed elevation of ethoxyresorufin-O-deethylase and/or glutathione-S-transferase activity in the DG and a decrease in lysosomal stability in hemocytes (TCS and E1). The TCS group was distinguished by having the highest level of DNA-fragmentation and the lowest concentrations of total glutathione, oxyradicals, lipofuscin, pyruvate, and lactate, reflecting total metabolic depression. These results show that selected PPCPs at low concentrations alter a variety of physiological processes in this animal model system.

The effect of seasonal temperature variation on behaviour and metabolism in the freshwater mussel (Unio tumidus)

Temperature plays a critical role in determining the biology of ectotherms. Many animals have evolved mechanisms that allow them to compensate biological rates, i.e. adjust biological rates to overcome thermodynamic effects. For low energy-organisms, such as bivalves, the costs of thermal compensation may be greater than the benefits, and thus prohibitive. To examine this, two experiments were designed to explore thermal compensation in Unio tumidus. Experiment 1 examined seasonal changes in behaviour in U. tumidus throughout a year. Temperature had a clear effect on burrowing rate with no evidence of compensation. Valve closure duration and frequency were also strongly affected by seasonal temperature change, but there was slight evidence of partial compensation. Experiment 2 examined oxygen consumption during burrowing, immediately following valve opening and at rest in summer (24 °C), autumn (14 °C), winter (4 °C), and spring (14 °C) acclimatized U. tumidus. Again, there was little evidence of burrowing rate compensation, but some evidence of partial compensation of valve closure duration and frequency. None of the oxygen compensation rates showed any evidence of thermal compensation. Thus, in general, there was only very limited evidence of thermal compensation of behaviour and no evidence of thermal compensation of oxygen compensation rates. Based upon this evidence, we argue that there is no evolutionary pressure for these bivalves to compensate these biological rates. Any pressure may be to maintain or even lower oxygen consumption as their only defence against predation is to close their valves and wait. An increase in oxygen consumption will be detrimental in this regard so the cost of thermal compensation may outweigh the benefits.

Response of antioxidant and biotransformation systems of selected freshwater mussels (Dreissena polymorpha, Anadonta cygnea, Unio tumidus, and Corbicula javanicus) to the cyanobacterial neurotoxin β-N-methylamino-L-alanine

Response of selected biotransformation and antioxidant enzymes (glutathione S-transferase (GST), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GPx)) of four different freshwater mussel species (Dreissena polymorpha, Corbicula javanicus, Anadonta cygnea, and Unio tumidus) was compared after a static exposure to 100 μg L−1 β-N-methylamino-L-alanine (BMAA) for 24 or 48 hours. Whereas D. polymorpha and A. cygnea did not show significant alteration in the activity of the selected enzymes, C. javanicus reacted with increased GST and GR activity after 24 hours and decreased CAT and GPx activity after 48 hours. U. tumidus displayed increased CAT and GR activity after 24 hours. Comparison between the concentration-dependent reaction of invasive D. polymorpha and native U. tumidus (exposure to 10, 100, and 500 μg L−1 BMAA) suggested a greater susceptibility of U. tumidus to BMAA. A further experiment on the time-dependent response to BMAA in U. tumidus gave an insight into the progression of the enzymatic response(s). An increase in CAT activity occurred after merely four hours, while a decrease of GPx activity was in turn only considerable after a longer exposure, for four or seven days. The data suggest that the BMAA exposure in freshwater mussels provokes changes in selected oxidative stress enzymes, which could result in the enhancement or inhibition of antioxidant systems.

Transport distance of invertebrate environmental DNA in a natural river.

Environmental DNA (eDNA) monitoring is a novel molecular technique to detect species in natural habitats. Many eDNA studies in aquatic systems have focused on lake or ponds, and/or on large vertebrate species, but applications to invertebrates in river systems are emerging. A challenge in applying eDNA monitoring in flowing waters is that a species' DNA can be transported downstream. Whether and how far eDNA can be detected due to downstream transport remains largely unknown. In this study we tested for downstream detection of eDNA for two invertebrate species, Daphnia longispina and Unio tumidus, which are lake dwelling species in our study area. The goal was to determine how far away from the source population in a lake their eDNA could be detected in an outflowing river. We sampled water from eleven river sites in regular intervals up to 12.3 km downstream of the lake, developed new eDNA probes for both species, and used a standard PCR and Sanger sequencing detection method to confirm presence of each species' eDNA in the river. We detected D. longispina at all locations and across two time points (July and October); whereas with U. tumidus, we observed a decreased detection rate and did not detect its eDNA after 9.1 km. We also observed a difference in detection for this species at different times of year. The observed movement of eDNA from the source amounting to nearly 10 km for these species indicates that the resolution of an eDNA sample can be large in river systems. Our results indicate that there may be species' specific transport distances for eDNA and demonstrate for the first time that invertebrate eDNA can persist over relatively large distances in a natural river system.

Aquatic Organisms and Petroleum Hydrocarbon Degrading Bacteria Associated with Their Digestive System

Laboratory investigation was carried out on the abundance and composition of bacteria in the digestive system of a total of 35 specimens, including bivalve molluscs, i.e. swan mussel Anodonta cygnea (Linnaeus, 1758) from Lake Spėra (Sirvintos district) and swollen river mussel Unio tumidus (Philipson, 1788) from the Curonian Lagoon near Juodkrantė, zebra mussel ( Dreissena polymorpha ) from the Curonian Lagoon near Juodkrantė and an anostracan – Chirocephalus josephinae (Grube, 1853) from a pond in Ilciukai village, Utena district, and in the water of related water bodies. Studies on bivalve molluscs (swan mussel and swollen river mussel), zebra mussel and an anostracan – Chirocephalus josephinae , as well as microbiological investigation of water demonstrated that the number of microorganisms in the digestive system of mollusc and anostracan species fluctuated and varied between different species and water bodies. The greatest percentage of HDB among total heterotrophic bacteria was found in the digestive system of swollen river mussels (21.53%) and in zebra mussels (19.99%) caught in the Curonian Lagoon and in the water of the lagoon (24%). A considerably smaller percentage of HDB was detected in the digestive system of swan mussels from Lake Spėra (17.6%) and in the water of the lake (16.66%). The smallest percentage of HDB was found in the digestive system of Chirocephalus josephinae (6.63%) and in the water of the Ilciukai pond (2.72%). According to the values of abundance of petroleum hydrocarbon-degrading bacteria (HDB) and total coliform bacteria (TCFB) in the digestive system of aquatic organisms we can state that the water ecosystem of Ilciukai pond was the least contaminated with petroleum, its products and sewage water, and the Curonian Lagoon water ecosystem was the most contaminated. Abundance of petroleum hydrocarbons degrading bacteria could be used as a bioindicator reflecting the level of ecosystem pollution petroleum and its products. DOI: http://dx.doi.org/10.5755/j01.erem.66.4.5300

Bioaccumulation of selected metals in bivalves (Unionidae) and Phragmites australis inhabiting a municipal water reservoir.

Urbanization can considerably affect water reservoirs by, inter alia, input, and accumulation of contaminants including metals. Located in the course of River Cybina, Maltański Reservoir (Western Poland) is an artificial shallow water body built for recreation and sport purposes which undergoes restoration treatment (drainage) every 4 years. In the present study, we demonstrate an accumulation of nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in water, sediment, three bivalve species (Anodonta anatina, Anodonta cygnea, Unio tumidus), and macrophyte Phragmites australis collected before complete drainage in November 2012. The mean concentrations of metals in the sediment, bivalves, and P. australis (roots and leaves) decreased in the following order: Fe > Mn > Zn > Cu > Cr > Ni > Pb > Co > Cd. A considerably higher bioconcentration of metals was observed in samples collected from the western and southern sites which undergo a higher degree of human impact. Sediments were found to be a better indicator of metal contamination than water samples. Interspecific differences in levels of metal accumulation were found between investigated unionids. U. tumidus accumulated higher levels of Cr, positively correlated with ambient concentrations, predisposing this species as a potential bioindicator of this metal in aquatic environments. On the other hand, species of Anodonta genus demonstrated higher accumulation of Cu and Cd. Positive correlations were found between Pb content in the sediments and tissues of all three bivalve species. In P. australis, metals were largely retained in roots except for Cd and Pb for which higher concentrations were found in leaves suggesting additional absorption of these metals from aerial sources. P. australis and bivalve from the Maltański Reservoir may be a potential source of toxic metals for animals feeding upon them and contribute to further contamination in the food chain.Electronic supplementary materialThe online version of this article (doi:10.1007/s10661-013-3610-8) contains supplementary material, which is available to authorized users.

Endocrine-Disrupting Effects of Compounds in Danish Streams

Effluents from municipal wastewater-treatment plants and scattered dwellings, as well as runoff from agricultural fields, are sources of endocrine-disrupting compounds (EDCs) in the aquatic environment. The present study investigated the correlation between the occurrence of EDCs in nine Danish streams using passive samplers (polar organic integrative samplers and silicone membranes) and determined their possible biological effects as assessed by mammal cell cultures and the mussel (Unio tumidus). The passive samplers and mussels were exposed simultaneously at the study sites. The extracts from the passive samplers were used to measure the concentrations of EDCs and the biological effects on the estrogen (ER), androgen (AR), and aryl hydrocarbon (AhR)-receptor transactivation. Male mussels were investigated for biomarkers of endocrine effects, such as the levels of vitellogenin-like proteins measured as alkali-labile phosphate (ALP). EDC concentrations, hormone-receptor transactivation (ER, AR, AhR), and level of ALP were greater downstream of wastewater-treatment plants compared with upstream sites and sites supposed to be relatively nonimpacted by wastewater. Furthermore, there was a significant positive correlation between in vitro AhR transactivation and frequency of ALP of male mussels. We conclude that wastewater effluent is an important source of endocrine-disrupting effects in the aquatic environment and that the combination of biological effect measurements and chemical analyses based on passive sampling is useful in the assessment of the ecological state of the aquatic environment.