Hazardous pollutants in the environment: Fish host-parasite interactions and bioaccumulation of polychlorinated biphenyls.

The present paper reports on the interrelationships of fish, parasites and the bioaccumulation of hazardous organic compounds in the Zemplínska Sírava water reservoir in eastern Slovakia, which is heavily polluted with polychlorinated biphenyls (PCBs). The concentrations of these contaminants were measured in various fish matrices (dorsal and abdominal muscle tissues, hepatopancreas, intestine wall and adipose tissue) of the freshwater bream, Abramis brama (Cyprinidae), and in its intestinal parasite Caryophyllaeus laticeps (Cestoda), which was used for the first time as a model for a PCB bioaccumulation study. Regarding the fish, the highest concentrations of PCBs were found in the intestine, followed by hepatopancreas and muscle tissues. The amounts of PCBs were higher in abdominal muscles than in their dorsal parts. Concentrations of ∑PCBs above the limits set by European regulations were detected in both muscle parts in the fish, confirming the persistent unfavorable conditions in this locality and high risk for biota and humans. Based on bioconcentration factor values (BCFs), PCBs reached much higher levels in cestodes compared to bream matrices. Some significant differences in PCB amounts between infected and uninfected bream were determined. Fulton's condition factor (CF) significantly differed in infected and non-infected fish (p ˂ 0.05), with CF values surprisingly lower in fish free of parasites compared to parasitized fish, which suggests a "mutualistic" relationship between the parasite and its host.

Transfer of Heavy Metals Through Three Components: Sediments, Plants and Fish in the Area with Previous Mining Activity.

This study aims to evaluate the ecological risk and distribution of heavy metals in sediment, plants and fish in a seriously polluted water reservoir in Krompachy, Slovakia. Special attention was given to the different food web positions of individual fish species (predators, omnivores) and their size. The degree of heavy metal contamination in sediments decreased in the order Cu > Pb > Cr > Hg > Cd, and their mutual proportion was largely consistent with concentrations found in aquatic plants, i.e. water sedges (Carex acutiformis). Of the seven fish species investigated, piscivorous perch (Perca fluviatilis) accumulated higher quantities of metal than fish situated at lower trophic levels. Interestingly, co-equal levels of heavy metals to those found in perch (P. fluviatilis) also occurred in rudd (Scardinius erythrophthalmus). The Hg values in some fish muscles exceeded the maximum permissible limits suggesting a persistent problem of old environmental burden from former mining activities.

Morphological abnormalities in fish parasites: a potential tool for biomonitoring natural contaminants?

A comparative study on the strobilar morphology of the tapeworm Proteocephalus percae (Müller, 1780) (Cestoda), a parasite of the perch Perca fluviatilis (L.), showed a high percentage of abnormally developed parasite individuals. The evaluation of biological samples showed seven types of morphological abnormalities, mostly related to reproductive organs of the model tapeworm species. The most commonly identified deformity was an incomplete segmentation of the strobila. A malformed ovary, which is a structural anomaly linked with proglottization and maturation of the strobila, was also shown to be rather frequent. Offish hosts (P. percae) were collected from two localities with different levels of heavy metal pollution, the highly contaminated water reservoir Ruzín and a control locality, the water reservoir Palcmanská Masa, which belongs to the European network of protected areas in Slovakia. Tapeworm abnormalities occurred more frequently in individuals from the contaminated environment (29.9%) compared with individuals from the control site (4.9%). The concentrations of heavy metals found in the parasites and their fish hosts from the heavily polluted reservoir support our assumption that the occurrence of abnormalities could be linked with the destructive effect of toxic substances. The present study also demonstrates that the enumeration of body deformities exceeding the common level of phenotypic variability of particular parasitic species could potentially be used as an indicator of environmental problems.

Potential Phytotoxic Effect of Essential Oil of Non-Native Species Impatiens parviflora DC.

Impatiens parviflora is non-native invasive plant species occupying large areas all over the Europe and threatens native communities by altering their species composition and reducing native biodiversity. The factor responsible for its spreading could be explained by releasing biochemical to the environment. On the other hands, high demand on secondary metabolites as potential source of new ecofriendly biocides could be beneficial. The analysis of I. parviflora essential oil (EO) led us to identify more than 60 volatiles. The main compound was hexahydrofarnesyl acetone, other dominant components were phytol, carvacrol, germacra-4(15),5,10(14)-trien-1-α-ol, and pentacosane. The potential phytotoxic effect of I. parviflora EO collected in two vegetation periods (summer and autumn) was evaluated on seed germination and root elongation of three dicot species (Raphanus sativus, Lepidum sativum, and Lactuca sativa) and on one monocot species (Triticum aestivum). The seed germination of only one dicot species, L. sativa, was affected by both EOs. In contrast, seed germination of monocot species T. aestivum was influenced only by the highest doses of EOs isolated from I. parviflora in autumn. The root elongation of tested plant species was less influenced by I. parviflora EOs. L. sativum showed sensitivity to one dose of EOs hydrodistilled in summer, while the monocot species was influenced by both EOs samples in highest doses. Our findings revealed that I. parviflora contained phenolics that were phytotoxic to the germination of some plant species, mainly at higher EOs doses, while root elongation of tested plants was not suppressed by essential oils.

Variability in responses of soil nematodes to trace element contamination.

Free-living soil nematodes and plant parasites were previously repeatedly tested for their use as bioindicators of soil contamination. We investigated soil nematode communities from grasslands in four different industrial areas in Slovakia to estimate their responses to heavy metals. We considered differences or similarities in behavioural reactions of nematodes to different quantities of selected heavy metals in the soil. Using the CCA analysis and t-value biplot diagrams with van Dobben circles, we split individual nematode genera by their tolerance/intolerance to the particular heavy metal into several clusters. Our results showed that (a) representatives of nematode genera showed concurrently positive and negative associations with two or more heavy metals, (b) most nematode genera expressed a strong positive relation with Ni and to a lesser extend with Cr and Zn, (c) taxonomically closely related nematodes did not demonstrated similar responses to the same pollutant. We assume that nematode genera with a higher level of tolerance to trace elements should be prioritized in the heavy metal bioindication instead of sensitive species, due to their longer persistence in the stressed environment and better indicative ability. We pointed nematode genera, which according to received results may serve as suitable sentinels for specific soil pollutants.

The effects of vegetation cover on soil nematode communities in various biotopes disturbed by industrial emissions.

Better understanding of interactions among belowground and aboveground components in biotopes may improve our knowledge about soil ecosystem, and is necessary in environment assessment using indigenous soil organisms. In this study, we proposed that in disturbed biotopes, vegetation play important role in the buffering of contamination impact on soil communities and decrease the ecological pressure on soil biota. To assess the effects of these interactions we compared nematode communities, known for their bioindication abilities, from four types of disturbed and undisturbed biotopes (coniferous forest, permanent grassland, agricultural field, clearings), where the main stress agent was represented by long-term acidic industrial emissions containing heavy metals (As, Cd, Cu, and Pb). To understand the ecological interactions taking place in studied biotopes, we studied abiotic factors (soil properties) and biotic factors (vegetation, nematode communities). Except significant increase in metals total and mobile concentrations in disturbed biotopes soil, we found acidification of soil horizon, mainly in the clearings (pH=3.68), due to SO2 precipitation. These factors has caused in clearings degradation of native phytocoenoses and decrease in decomposition rate characterized by high amount of organic matter (Cox=4.29%). Nematodes reacts to these conditions by shifts in trophic structure (bacteriovores to fungal feeders), increase in c-p 2 genera (Aphelenchoides, Acrobeloides, and Cephalobus), absence of sensitive groups (c-p 3-5, omnivores, predators), and decrease in ecological indices (SI, MI, MI2-5, H'). Similar contamination was found in forest biotope, but the nematodes composition indicates more suitable conditions; more complex community structure (presence of sensitive trophic and higher c-p groups), higher abundance and indices values, comparable with less stressed field and grassland biotopes. As showed our results, the vegetation undoubtedly plays an important role not only as a resource of services indispensable for the ecosystem, but also as a significant buffer of negative impacts acting within.

Host-parasite relationships as determinants of heavy metal concentrations in perch (Perca fluviatilis) and its intestinal parasite infection.

The concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn and their bioconcentration factors (BCFs) were determined in two intestinal parasites, an acanthocephalan, Acanthocephalus lucii, a tapeworm, Proteocephalus percae, present in the same host, the European perch (Perca fluviatilis, L.), in the heavily polluted Ruzín reservoir in eastern Slovakia. The bioaccumulation of heavy metals in the fish organs and parasites was studied for acanthocephalan and tapeworm monoinfections or mixed infections by the two parasites and for the size of their parasitic infrapopulations. Bioconcentration factors (c[parasite]/c[muscle tissue]) showed that the concentrations of As, Ni, Pb and Zn were higher in mixed infections than in monoinfections. Negative correlations between heavy metal concentrations in perch organs and the parasites were found. For example, higher concentrations of Ni and Zn in both parasite species corresponded with lower metal concentrations in perch and hard roe. Likewise, significant negative relationships between metal concentrations in fish organs and number of parasites were noticed with lower levels of Pb in fish harbouring higher numbers of tapeworms. Similarly, in both parasite species the concentrations of some essential elements (Cr, Mn) were lower at high infection intensities compared to low intensities. Our study revealed that the differential concentration of heavy metals in perch organs was affected by the type of infection (mono- or mixed-infection), and needs to be considered in field ecotoxicological and parasitological studies as a potentially important factor influencing the pollutant concentrations in fish.

Diversity and food web structure of nematode communities under high soil salinity and alkaline pH.

A long-term and intensive magnesium (Mg) ore processing in Slovenské Magnezitové Závody a.s. in Jelsava has resulted in a high Mg content and alkaline pH of the soil environment, noticeable mainly in the close vicinity of the smelter. Nematode communities strongly reacted to the contamination mostly by a decrease in abundance of the sensitive groups. Nematodes from c-p 1 group and bacterivores, tolerant to pollution played a significant role in establishing the dominance at all sites. With increasing distance from the pollution source, the nematode communities were more structured and complex, with an increase in proportion of sensitive c-p 4 and 5 nematodes, composed mainly of carnivores and omnivores. Various ecological indices (e.g. MI2-5, SI, H') indicated similar improvement of farther soil ecosystems.

Nematodes as bioindicators of soil degradation due to heavy metals.

The effect of distance from a heavy metal pollution source on the soil nematode community was investigated on four sampling sites along an 4 km transect originating at the Kovohuty a.s. Krompachy (pollution source). The soil nematode communities were exposed to heavy metal influence directly and through soil properties changes. We quantified the relative effects of total and mobile fraction of metals (As, Cd, Cr, Cu, Pb, and Zn) on soil ecosystem using the nematode community structure (trophic and c-p groups,) and ecological indices (Richness of genera, H', MI2-5, etc.). Pollution effects on the community structure of soil free living nematodes was found to be the highest near the pollution source, with relatively low population density and domination of insensitive taxa. A decrease in heavy metals contents along the transect was linked with an increase in complexity of nematode community. The majority of used indices (MI2-5, SI, H') negatively correlated (P < 0.05 or P < 0.01) with heavy metals content and were sensitive to soil ecosystem disturbance. Contamination by heavy metals has negatively affected the soil environment, which resulted in nematode community structure and ecological indices changes. Results showed that the free-living nematodes are useful tools for bioindication of contamination and could be used as an alternative to the common approaches based on chemical methods.

Perch and its parasites as heavy metal biomonitors in a freshwater environment: the case study of the Ruzín water reservoir, Slovakia.

Heavy metal concentrations were determined in 43 perches (Perca fluviatilis) and in two of its most common parasites, the acanthocephalan Acanthocephalus lucii and the cestode Proteocephalus percae, collected in the period 2009-2010 from Ruzín, a seriously polluted water reservoir in Slovakia. Samples of muscle, liver, kidney, brain, male and female reproductive organs and adipose tissue of fish and both parasites were analyzed for As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn, by ICP-MS. Mean concentrations of individual heavy metals in all fish samples decreased in the order zinc > copper > manganese > mercury > arsenic > chromium > cadmium > nickel > lead. Zinc was found to be the dominant element and its antagonistic interaction with copper was confirmed. The kidney was a key target organ receiving the highest mean concentrations of all analyzed metals, but some metals showed specific affinity for particular tissues. In terms of human health, concentration of Hg in fish muscle, which exceeded more than two-times its maximum level admitted in foodstuffs in European countries, is of great importance and should be taken into account. Bioaccumulation factors (C([parasite])/C([fish tissue])) calculated for all elements indicated much higher detection skills of A. lucii and P. percae parasites than fish organs and hence, present results allow proposing both parasite models as useful tools to monitor aquatic environmental quality. Acanthocephalans, however, seem to be superior for heavy metal monitoring, also demonstrated under experimental conditions. Present results also indicate the decreasing heavy metal burden of the reservoir and its gradual recovery in the course of time.

Nematode community structure in the vicinity of a metallurgical factory.

Soil nematode communities (taxa composition, trophic structure, ecological indices) in the area of metallurgical factory (Oravské ferozliatinárske závody) in Siroká, Northern Slovakia were investigated in 2009. The factory belongs to main sources of emissions originated by ferroalloy production in this region. Four sites (meadows) were selected in a downwind direction from the factory: site A was located 0.85 km far from the factory, and the other sites were maintained in approximately 2-km intervals from each other. Chemical analysis of soil samples showed low concentrations of heavy metals (As, Cd, Cr, Cu, Ni, Pb and Zn), with all values being under Slovak limit concentrations of heavy metals in soils. Only the Cd content in the soil sample from site A slightly exceeded the allowable threshold, but it was decreasing with the distance from the factory, similarly as remaining metals except Cr, with slightly increasing trend of concentration. Within 64 identified nematode genera, the Helicotylenchus, Paratylenchus, Pratylenchus, Acrobeloides, Cephalobus and Rhabditis were most common and eudominant. This was clearly reflected on the trophic structure of nematode communities, where plant feeding nematodes and bacteriovorous prevailed. Significant negative correlation (P < 0.05) was observed between the abundance of bacteriovores and the concentration of Cu in the soil. On the other hand, fungivores showed significant correlation with Ni and Cr (P < 0.05) as well as predators with Cd, Pb and Zn contents in the soil (P < 0.01). The highly significant correlation (P < 0.05; P < 0.01) was found between As, Cd, Ni, Pb and Zn and Maturity Index 2-5. A negative relationship was detected between Maturity Index and the concentration of Cr in the soil (P < 0.01). On the other hand, Cu was in positive correlation with MI values. The MI, reflecting the degree of disturbances and changes in the structure and function of the soil ecosystem, was found to be the most sensitive indicator among all used indices.