Tímea Brázová

Perch and Its Parasites as Heavy Metal Biomonitors in a Freshwater Environment: The Case Study of the Ružín 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 Ružín, 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.

Ultrastructural features of the spermatozoon and its differentiation in Brandesia turgida (Brandes, 1888) (Digenea, Microphalloidea, Pleurogenidae)

Spermatological characters of the digenean Brandesia turgida (Brandes, 1888), an intestinal parasite of the frog Pelophylax ridibundus (Pallas, 1771), have been investigated by means of transmission electron microscopy for the first time. The process of the spermatozoon formation begins with the appearance of the differentiation zone bordered by cortical microtubules and containing two centrioles associated with striated rootlets and with an intercentriolar body. The intercentriolar body is made up of seven distinct electron-dense plates, two less electron-dense, and four electron-lucent zones. The orthogonal development of the two flagella is followed by a flagellar rotation and their proximodistal fusion with the median cytoplasmic process. This process is accompanied by an extension of both the mitochondrion and nucleus into the median cytoplasmic process. The mature spermatozoon of B. turgida contains two parallel axonemes of unequal lengths with the 9 + “1” trepaxonematan pattern, mitochondrion, nucleus, parallel cortical microtubules, four electron-dense attachment zones, an external ornamentation of the plasma membrane, and electron-dense glycogen granules. The anterior extremity of the male gamete contains one complete centriole, a small component of the central element of the second centriole, and peripheral cortical microtubules (up to 45). The posterior extremity of the mature spematozoon exhibits tubular elements of the disorganized axoneme. The present study provides the first data on spermiogenesis within the family Pleurogenidae. Variations of the spermatozoa ultrastructural characters within Digenea, in particular, between different families of the superfamily Microphalloidea, are discussed.

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 Ružín 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 Jelšava 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.

Influence of selected heavy metals (As, Cd, Cr, Cu) on nematode communities in experimental soil microcosm

Summary In this study, the effects of arsenic, cadmium, copper and chromium treatments were examined on a nematode community structure and proportion of functional groups in the microcosm for 30 days. The toxic effects on the nematode community did not correspond with metals mobility (EDTA extraction) in soil as it was expected. The most toxic element with a significant degradation of community structure was chromium (low mobile), which negatively affected almost all observed ecological parameters (abundance, diversity and ecological indices). On the other hand, cadmium and arsenic influence was negligible even in the plots treated with the highest concentrations and the communities resembled to the control samples. Copper showed a stimulative effect on the community under low concentration (40 mg.kg-1), while under higher concentrations the stimulation was replaced by stress responses. The widely used ecological indices, such as the Maturity Index 2-5, Structure Index, and Shannon-Weaver Index and c-p groups showed the best bioindication potential among nematode parameters.

Ultrastructural characteristics of the vitellarium of Brandesia turgida (Brandes, 1888) (Digenea: Pleurogenidae) and an examination of the potential usefulness of such vitelline traits in digenean systematics

Transmission electron microscopical observations were made on the vitelline structure of the digenean Brandesia turgida (Brandes, 1888) collected from crypts within the intestinal wall of the frog Pelophylax ridibundus (Pallas, 1771). Ultrastructural details of the vitelline follicles of B. turgida include: (a) the presence within the vitellarium of a single type of cell, i.e. vitellocytes at different stages of their development; (b) a narrow region between the vitellocytes filled with the processes of surrounding parenchymal cells; and (c) the occurrence of the junctional complexes between the vitellocytes and the surrounding parenchymal cells at the periphery of the vitelline follicles. It is shown that the vitelline globules and a few lipid droplets are the main inclusions resulting from vitellocyte synthetic activity. The limited amount of nutritive reserves in the vitellocytes can be explained by the nature of the parasite’s life-cycle, which is characterized by fully-embryonated intrauterine eggs containing a fully-formed miracidium. Despite the small number of digenean species studied in relation to their vitelline cytoarchitecture, two structural patterns of the vitellarium can be elucidated; these are examined in terms of digenean systematic relationships.

Effect of heavy metals on soil nematode communities in the vicinity of a metallurgical plant in North Slovakia

Abstract The effect of industrial pollution from chromium ferroalloys production on soil free-living nematode assemblages, c-p groups and generic composition was investigated along 7-km transect. From trace elements (Cr, Cu, Ni and Pb), only chromium exceeded the thresholds for uncontaminated soils (10 mg.kg-1) near the pollution source. In contrast mobilizable fraction of Cr has increased with the distance from the pollution source and was found to be positively correlated with Cox, soil pH, and moisture. Generic richness (nematode diversity) was also higher at remote sites. The low contamination has no significant impact on the nematode communities as illustrated by the c-p groups composition and balanced community structure. Widely applied ecological indices SI and EI also proved maturing ecosystem without any significant stress responses