Parasites of the shore crab Carcinus maenas (L.): implications for reproductive potential and invasion success.

The European shore crab, Carcinus maenas, is one of the most successful marine invasive species. Its success has been in part attributed to the loss of parasites, rekindling an interest in host-parasite interactions and impacts on host fitness in this crab. In the present study, we investigated C. maenas populations from Europe, South Africa and Australia for parasites, and assessed their impact on the fitness of male crabs. For the shore crab, testes weight along with success in mating competition is traded off against other life-history traits. We therefore used this parameter as an indicator both for reproductive fitness and a possible resource trade-off in response to parasite infestation. In the native range, crabs infested with Sacculina carcini showed significantly lower testes weight than uninfected crabs. However, helminth parasites did not generally cause reduced testes weights. Crab populations from South Africa and Australia were either parasitized at very low prevalences, or were completely parasite free. However, no population level effect of this parasite release was reflected in testes weight. These findings do not support a severe fitness impact of helminth parasites on C. maenas, which questions the role of parasites on its population dynamics, both in the native area and for invasive success.

Comparative population dynamics of a generalist (Ixodes ricinus) and specialist tick (I. hexagonus) species from European hedgehogs.

Although the population dynamics of the tick Ixodes ricinus are relatively well studied, those of other Western European tick species are largely unknown. Moreover, there is very little information related to the interactions between I. ricinus and other ticks. Such knowledge, however, is of special interest in respect to the epidemiology of tick-borne pathogens such as Borrelia spp. We compared the dynamics of the generalist I. ricinus with the nest-dwelling hedgehog specialist, I. hexagonus. Both species were collected from hedgehogs from a naturally infested experimental population between 2006 and 2008. Ticks were collected once a month from March to October from each hedgehog counted and the life history stage and species determined. All hedgehogs harboured both tick species. Nymphs, females and males of I. ricinus showed clear bimodal seasonal distributions with peaks in spring and autumn, while larvae peaked only in summer. The density of I. hexagonus life stages was low during the whole investigation period and seasonal fluctuations of population density were much weaker compared to I. ricinus. Nymphs and larvae showed comparatively little change in population size and no consistent period of peak density. Females showed a single peak in summer and males were found only occasionally on hedgehogs. We suggest density-dependent mechanisms regulating the population density of the specialist I. hexagonus but not of the generalist I. ricinus.

The influence of human settlements on the parasite community in two species of Peruvian tamarin.

Although there is a growing recognition that the transfer of diseases between humans and non-human primates can be of great significance for conservation biology, there have been only a few studies focusing on parasites. In this study, saddleback (Saguinus fuscicollis) and moustached tamarin (Saguinus mystax) from the rainforest of the Peruvian lowlands were used as models to determine helminth parasite associations between canopy-dwelling primate species and a nearby human settlement. The human population showed high prevalences of infestation with a number of nematodes, including Ascaris lumbricoides (88.9%), Trichuris trichiura (37%) and hookworms (55.6%). However, the ova of these geohelminths were not detectable in tamarin faeces. Thus, no direct parasite transfer from humans to non-human primates could be documented. However, tamarin groups with more frequent contact to humans and their facilities had significantly higher prevalences and egg output of Prosthenorchis elegans, an important primate pathogen, than a forest group. In contrast, a cestode was significantly more common with more egg output in sylvatic than in human-associated groups. Human alteration of the habitat is likely to play a major role in determining the occurrence, prevalence and intensity of helminth infestation of wild non-human primates.

Divergence between Asian, European and Canadian populations of the monogenean Pseudodactylogyrus bini indicated by ribosomal DNA patterns.

The monogenean Pseudodactylogyrus bini parasitizes the gills of eels belonging to the genus Anguilla. Circumstantial evidence suggests that the parasite has been spread accidentally from the Pacific area (East Asia) to Europe by the intercontinental eel trade. This is based on early descriptions of the parasites from Asian regions and the lack of records of the parasites in Europe before 1977. In addition, the susceptibility of European eels to infections with the parasite is significantly higher compared to that of Japanese eels, which could indicate that the European eel had not undergone co-evolution with this parasite. The present study was undertaken to elucidate the origin of the parasite by using molecular tools. Parasite samples were obtained from Europe (Germany), Asia (Taiwan) and Nova Scotia, the latter of which is the first record of P. bini in Canada. Sequencing of rDNA comprising part of the internal transcribed spacer 1 (ITS1) gene, 5.8S and part of ITS2 (1323 bp) showed that P. bini isolates from the first two regions showed high variability. One sequence was found both in a number of Asian parasites and with one to a few transitions in European parasites, which could indicate that they were split recently into the two regions. Other sequence variations suggested that one or a few genotypes of P. bini were imported on one occasion from Asia to Europe and that the two geographic isolates subsequently developed differently in the two regions. The Nova Scotian/Canadian isolates showed no variation and were found to be unique compared to the European and Taiwanese forms, indicating that this population is independent in origin. This could indicate that the Canadian parasites were introduced to North America on another occasion and independently of the European colonization.

Tick-induced blood loss leads to regenerative anaemia in the European hedgehog ( Erinaceus europaeus).

Although there is an increasing understanding of the role of parasites in their host dynamics, accurate, quantitative estimates of parasite caused morbidity in wild animals are rare. Here, we examine the possible impact of 2 tick species (Ixodes ricinus, I. hexagonus) on the condition of the European hedgehog (Erinaceus europaeus). For this, we tested for correlations between blood parameters of 36 adult hedgehogs from an experimental population enclosed in a natural habitat and their tick infestation over a period of 8 months (March-October 2007). We found correlations between the tick infestation and the concentration of red blood cells, haemoglobin, haematocrit, MCH, MCHC, thrombocytes, lymphocytes and neutrophils. These results indicate that ticks can induce anaemia in the hedgehog. The peripheral blood characteristics and the erythrocyte indices characterize this anaemia as haemorrhagic and regenerative. During the course of our study the hedgehogs of our population showed below normal mortality but morbidity was found to be high resulting from the blood loss caused by the feeding activity of the ticks.

Description of a new Echinorhynchid species (Acanthocephala) from the European eel, Anguilla anguilla, in Germany, with a key species of Acanthocephalus in Europe.

Acanthocephalus rhinensis n. sp. is described from the European eel. Anguilla anguilla (Linnaeus, 1758), collected in the Rhine River near the city of Karlsruhe, Germany. It is the sixth species of Acanthocephalus Koelreuther, 1771 described from European fish. Four other species are known from amphibians. The new species is distinguished from the other 5 species infecting fish by having a 1.2-mm-long proboscis armed with 15-21 rows of 13-16 hooks each, lemnisci about as long as receptacle, oblong and slightly pre-equatorial testes, and thin fusiform eggs, measuring 85-95 X 15-18 micro. Testes in the other European species are usually round to ovate, except in Ac. anguillae (Müller, 1780) Lühe, 1911 where they are also elongated but postequatorial. It aslo has an orange-brown belt encircling the anterior end of the trunk. The comparative distribution of Acanthocephalus in Europe and North America, and the validity of 2 presumably questionable species are discussed, Acanthocephalus falcatus (Froelich, 1789) Lühe, 1911 and Ac. Paronai (Cendorelli, 1897) Meyer, 1932. A dichotomus key distinguishing Ac. rhinensis from the other 9 European species is also included. The new species was only found in 3 of 390 eels examined during 11 yr; this may be related to the changing benthos community in the Rhine River.

Acanthocephalus reunionensis n sp (Acanthocephala: Echinorhynchidae), a parasite of Anguilla species (Anguillidae) from Reunion Island.

In a survey of 118 eels Anguilla bicolor, A. marmorata and A. mossambica, (Anguillidae) indigenous to Reunion Island in the Mascarene island group, western Indian Ocean, a new species of acanthocephalan, Acanthocepholus reunionensis n. sp., was found. With a proboscis hook formula of 19 rows of 4-5 hooks, and elongated cement glands arranged in three pairs, this species differs from all other species in the genus. This is the first record of the genus Acanthocephalus occurring in eels from the African Region.

Occurrence of Anguillicola crassus (Nematoda: Dracunculoidea) in Japanese eels Anguilla japonica from a river and an aquaculture unit in SW Taiwan.

The infection by swimbladder nematodes of the genus Anguillicola (Dracunculoidea: Anguillicolidae) was examined in 2 populations of the Japanese eel Anguilla japonica in SW Taiwan. Wild eels from the Kao-Ping river were compared with cultured eels from an adjacent aquaculture unit. Only the cosmopolitan species Anguillicola crassus was present. Among wild eels, prevalence of infection varied between 21 and 62%, and mean intensity between 1.7 and 2.7 for adult worms. Similar intensity values (1.3 to 2.8) were recorded for the larvae. In cultured eels, prevalence as well as mean intensities were higher. In the cultured hosts, mean larval intensities exceeded those of adult worms 2-fold, and maximum larval intensities were 4- to 5-fold higher than in eels from the river. In cultured eels, dead larvae were also more abundant than in wild eels. We conclude that infrapopulations of A. crassus in Japanese eels are regulated by the defense system of this host, intraspecific density-dependent regulation being less likely as the major regulatory mechanism. No influence of the parasite on eel condition was found in either wild or cultured eels, indicating a low or moderate pathogenic effect of A. crassus on this host. This study shows that A. crassus is moderately common in cultured and wild Japanese eels in Taiwan, where the parasite is endemic.

Anguillicola papernai (Nematoda: Anguillicolidae) and other helminths parasitizing the African longfin eel Anguilla mossambica.

The swim bladder nematode Anguillicola papernai Moravec & Taraschewski, 1988 has been investigated as regards its occurrence in longfin eels Anguilla mossambica (Peters) in rivers in South Africa. A. papernai revealed a prevalence of around 50% and a mean intensity of about 6 adult worms at 1 sampling site but were less abundant in 3 others. Field observations suggest a more narrow habitat preference than that of Anguillicola crassus and a seasonal pattern of abundance. African longfin eels harboured a poor helminth community. In addition to A. papernai, 2 gastro-intestinal nematodes occurred, the stomach worm Heliconema longissimum Ortlepp, 1923 as the dominant species, and the intestinal Paraquimperia africana Moravec, Boomker & Taraschewski, 2000. Experiments were undertaken using European eels Anguilla anguilla (Linnaeus) and copepods as laboratory hosts. The morphology of larvae and adult parasites obtained from these experimental hosts is described. The ultrastructure of adult worms recovered from wild longfin eels was studied. The 'papilla-like excrescences of fibrous structure' on the adult worms' cuticle, as mentioned in the original description, are in fact the attachment points of thick cords of fibers interconnecting the epicuticle with the hypodermis. Such a structure has not yet been described from any other species of Anguillicola Yamaguti, 1935. At present in South Africa, Mozambique and Madagascar attempts are on the way to establish an eel management like in Asia and Europe including eel farming. In this context, care should be taken to prevent the introduction of non-endemic eel parasites into Africa and Madagascar. On the other hand, the future commercial management of African eel species should not lead to the spread of A. papernai or other parasites of African eel species to Europe or elsewhere. In this study A. papernai has been experimentally demonstrated to be capable of reproducing in the European eel and of using European copepods as intermediate hosts.

Host-parasite interactions in Acanthocephala: a morphological approach.

In this review recent morphological and histochemical descriptions have been compiled of (mainly outer) features of all developmental stages of the Acanthocephala as well as what is known about the host's defence measures directed against these worms. From acanthors, for instance, it is documented how they escape melanization inside the haemocoel of a suitable intermediate host after they have been activated and released from their eggshell enclosure in the gut of the arthropod. Acanthors possess a complex set of eggshell-envelopes and interstices that fulfil different tasks. While the sequence of events inside the intermediate host's haemocoel is rather well known, what happens in paratenic hosts has been little studied. In final hosts the host-parasite interactions depend on the systematic affiliation of the parasite as well as the host and on the depth of penetration of each acanthocephalan species in the intestinal wall of the host. The mode of attachment also influences the microhabitat preference inside the gut. Mammals often reveal symptoms of high morbidity when infected with acanthocephalans, while fish seem to tolerate high intensities of worms deeply penetrating into their intestinal wall without showing pronounced symptoms of disease. The review also treats the subjects of host specificity, nutrient uptake and metabolism of the worms as well as their absorbance of metals and other elements. The high absorbance capacity for heavy metals suggests the usefulness of acanthocephalans as bioindicators.

Element concentrations in the archiacanthocephalan Macracanthorhynchus hirudinaceus compared with those in the porcine definitive host from a slaughterhouse in La Paz, Bolivia.

Concentrations of lead and cadmium, determined by electrothermal atomic absorption spectrometry, and concentrations of the elements barium, cadmium, copper, iron, magnesium, manganese, nickel, lead, selenium and strontium, determined by inductively coupled plasma mass spectrometry, in the acanthocephalan Macracanthorhynchus hirudinaceus and its porcine final host, sampled at a slaughterhouse in La Paz, Bolivia, were compared. Inductively coupled plasma mass spectrometry analysis revealed that most of the elements were found at higher concentrations in the acanthocephalan than in different tissues of its host. The bioconcentration of elements in M. hirudinaceus compared with the host intestine, listed in order of decreasing values, was as follows: Cd > Pb > Ni > Sr = Cu > Mg > Se > Fe = Mn = Ba. Analysis by electrothermal atomic absorption spectrometry showed that M. hirudinaceus contained 85, 85, 56 and 24 times higher lead levels compared with hosts muscle, liver, kidney and intestine, respectively. The mean cadmium concentration of the parasite was 32 times higher than that of the liver and five times higher compared with porcine kidney. The metal distribution within the body of M. hirudinaceus was as follows: cement gland > testes > lemnisci > eggs = tegument for lead and lemnisci > testes > cement gland > tegument > eggs for cadmium. Therefore, the hypothesis that parasites excrete toxic metals with the shells of their eggs seems not to be valid for M. hirudinaceus. It is concluded, that not only eoacanthocephalans and palaeacanthocephalans parasitising fish, but also archiacanthocephalans from mammalian hosts, are able to bioaccumulate metals.

Relative concentrations of heavy metals in the parasites Ascaris suum (Nematoda) and Fasciola hepatica (Digenea) and their respective porcine and bovine definitive hosts.

The concentrations of lead and cadmium determined by electrothermal atomic absorption spectrometry were significantly higher in the liver and kidney, respectively, of pigs than in their intestinal nematode parasites Ascaris suum. There was no clear pattern in the distribution of lead within the ascarids, but cadmium concentrations were highest in the intestine. A parallel investigation of cattle naturally infected with the liver fluke, Fasciola hepatica, revealed interesting differences. Although the cadmium content of F. hepatica was considerably lower than that in the tissues of cattle, the concentration of lead in the digenean was on average 172, 53 and 115 times higher than in the muscle, kidney and liver of the host. Furthermore, there was a significant positive correlation between the weight of individual F. hepatica and their lead burden. The lack of appreciable heavy-metal accumulation in A. suum is consistent with results for the nematode Anguillicola crassus in fish. However, although lead concentrations in the liver fluke F. hepatica were considerably elevated above host tissue levels, the degree of heavy-metal accumulation was relatively low when compared to that of acanthocephalans and cestodes of fish.

Treatment of fish parasites: 5. The effects of sym. triazinone (Toltrazuril) on fish parasitic ciliophora (Ichthyophthirius multifiliis FOUQUET, 1876, Apiosoma amoebea GRENFELL, 1884, Trichodina sp. EHRENBERG, 1831).

For chemotherapy of fish parasitized by different Ciliophora (Protozoa) toltrazuril was tested in vivo and in vitro against skin and gill parasitizing species (e.g. Ichthyophthirius multifiliis, Apiosoma amoebea and Trichodina sp.). For in vitro treatment naturally infected fish were incubated at 20 °C for 0.3,1,2,4.5 h in water containing 0,1,5,10,20 or 50 µg toltrazuril/ml. Lethal damages already occurred in about one third of the trophozoites of I. multifiliis after incubation in 5 µg/ml for 4.5 h, and in more than two thirds of the trophozoites after incubation in 10 µ/ml for 2 h. A few trophozoites, however, were still able to leave their hosts, to encyst and to produce theronts. However, when treatment was done by intermittent therapy (1×10 µg/ml for 2 h, first day; 1 × 20 µg/ml for 1 h, second day; 1 × 20 µg/ml for 1 h, third day) all the trophozoites were lethally damaged. The damages consisted in the destruction of the outer cell membranes, of the cilia, and of the mitochondria, as well as in the complete abolishment of the ribosomes and in the enlargement of the nuclear space. After in vitro treatment (10 µg/ml, 2 h) all the trophozoites were lethally damaged. In contrast to the trophozoites, the free-swimming theronts of I. multifiliis were not affected by the drug. In vivo treatment starting with 20 µg/ml for 1 h led to severe damages in A. amoebea, which were intensified after treatment with 50 µg/ml for 0.3 h. The specimens were heavily contracted, and the oral cilia were redrawn. Furthermore, the pellicular pores seen in the surface of controls were not detectable. Despite the affections caused by the treatment the parasites did not drop off their hosts. In vivo treatment against Trichodina sp. led to a reduced motility in these parasites starting with 10 µg/ml for 2 h. Incubation with 20 µg/ml for 1 h caused a complete stop of motion in most of the specimens. The highest dose (50 µg/ml; 0.3 h) only caused a dropping off in about one third of the specimens from their hosts. Treated specimens of Trichodina sp. had a more flattened appearance compared to untreated controls, and the epistomial disc was drastically enlarged. From these experiments it is suggested that treatment against the trophozoites of I. multifiliis should be done by intermittent therapy according to the following scheme: 1st day: 10 µg/ml, 2 h, 2nd day: 20 µg/ml, 1 h; 3rd day: 20 µg/ml, 1 h. In the cases of Apiosoma spp. and Trichodina spp. infected fish incubating with 50 µg/ml for only 20 minutes is recommended.

Treatment of fish-parasites: 7. Effects of sym. triazinone (toltrazuril) on developmental stages of Myxobolus sp. Bütschli, 1882 (myxosporea, myxozoa): A light and electron microscopic study.

In research for chemotherapy of fish parasitized by myxosporeans toltrazuril(1) was tested in vivo against Myxobolus sp., parasitizing the connective tissue in gills of the bream, Abramis brama. Naturally infected breams were incubated at 20°C in water containing 0, 5, 10 or 20 µg toltrazuril/ml or the pure solvent for 4 or 2 h, respectively. After replacing the fish into fresh water, they were sacrificed on day 2 after the treatment and the pseudocysts were studied by means of transmission electron microscopy. It was found that the drug caused severe damages in all developmental stages of Myxobolus sp. except for the mature spores. Starting with a dose of 5 ug/ml and 4 h exposure, a destruction of the mitochondria and a decrease in the number of ribosomes were observed in the uni- and multicellular stages. In sporoblasts while developing the polar capsules the perinuclear space was enlarged in most of the specimens. The karyoplasms were more electron lucent compared to those of untreated controls. A focal lysis of the karyoplasm was observed in early pansporoblasts (characterized by primordia of the polar tubes). Treatment with 10 µ/ml for 4 h had more pronounced effects. The shape of these unicellular and multicellular stages was, however, not changed after treatment with 5 or 10 µg toltrazuril for 4 h, whereas 20 µg toltrazuril/ml for 2 h altered the surface of both stages and led to considerable degenerations of the cytoplasm. In premature pansporoblasts an extrusion of the polar capsules (leaving the capsulogenic cells) was caused when incubated in 20 µm toltrazuril/ml. The pure solvent had no effects on developmental stages of Myxobolus sp.. From these experiments it is suggested that chemotherapy against Myxobolus sp. should be accomplished by bathing the fish in aerated containers with 10 µg toltrazuril/ml for 4 h. This treatment will decrease considerably the output of spores. However, since the mature spores are not affected, the treatment has to be repeated within several months. Fish with extended skin lesions, caused by net-catching or infections by fungi, should be treated under careful observation, because these factors decrease the tolerance to the drug.

Metabolism of long-chain fatty acids, alcohols and alkylglycerols in the fish parasite Paratenuisentis ambiguus (Acanthocephala).

Specific differences between the acyl composition of lipids of the helminth Paratenuisentis ambiguus and its host eel, as shown previously, prompted us to study the lipid metabolism in this intestinal fish parasite. Adults and larvae of P. ambiguus were fed various lipid precursors, e.g., fatty acids, long-chain alcohols and 1-O-alkylglycerols, which may occur as common nutrients of intestinal parasites. Incorporation of [1-14C]palmitic acid into neutral and polar lipids was found to be similar under aerobic and near-anaerobic conditions. In adult parasites maintained in culture medium supplemented with glucose, [1-14C]palmitic acid was incorporated mainly into triacylglycerols and phosphatidylcholines, whereas [1-14C]oleic acid was incorporated preferentially into triacylglycerols. In fasted adults, as well as in larvae, [1-14C]oleic acid was mainly transferred to phosphatidylcholines. Lipolytic activity was detected in adult parasites that had been incubated with radioactive trioleoylglycerol. [1-14C]Hexadecan-1-ol was oxidized in P. ambiguus at a high rate to labeled palmitic acid, which was incorporated into various lipid classes of P. ambiguus. Small but significant proportions of radioactivity from hexadecan-1-ol were incorporated into ether glycerolipids of the parasite. A more direct precursor in ether glycerolipid metabolism, i.e., rac-1-O-[1'-14C]hexadecylglycerol, was incorporated into alkyl and 1'-alkenyl moieties of choline and etha-nolamine ether-glycerophospholipids of P. ambiguus in high yield. High proportions of labeled diacylglycerols, triacylglycerols and steryl esters were detected in surface lipids as well as lipid extracts of the culture media after incubation of P. ambiguus with [1-14C]palmitic or [1-14C]oleic acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Sterol and fatty acid composition of neutral lipids of Paratenuisentis ambiguus and its host eel.

The sterol composition of free sterol and steryl ester fractions of the fish parasite Paratenuisentis ambiguus was determined. In addition, the fatty acid composition of various neutral lipid classes, i.e., wax esters, steryl esters, triacylglycerols and free fatty acids, as well as the composition of the 1-O-alkyl moieties of total ether glycerolipids of the parasite, were investigated. The results of these studies were compared with those obtained on the intestinal tract tissue of its host, the eel (Anguilla anguilla). Cholesterol is the major sterol in both P. ambiguus and A. anguilla. However, the sterols of P. ambiguus contain high proportions (> 20%) of other sterols, such as campesterol and various dehydrosterols. [e.g., 7-dehydrocholesterol and cholesta-5,22(E)-dienol]. The presence of these minor sterols agrees with the known biotransformations of exogenous sterols in various helminths. Considerable differences are found in the fatty acid composition of neutral lipid fractions, as well as the total lipid extract from the endoparasite as compared to the host tissue. In particular, eicosapentaenoic acid (20:5n-3), other polyunsaturated fatty acids, such as 20:4n-6, 22:5n-3 and 22:6n-3, as well as long-chain saturated fatty acids, such as 20:0, are generally enriched in the neutral lipid fractions of the parasite as compared to those of infected eel intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Accumulation and distribution of platinum and rhodium in the European eel Anguilla anguilla following aqueous exposure to metal salts.

The platinum group metals (PGM) Pt and Rh are emitted into the environment mainly by catalytic exhaust gas converters of cars and by effluents of hospitals, which use Pt based anti-cancer drugs. However, there is still a lack of information on the availability of these precious metals to the biosphere. As PGM accumulate in sediments of aquatic ecosystems we focused our study on the uptake of the noble metals by European eels, Anguilla anguilla. Therefore, eels were exposed in tap water and humic water containing Pt(4+) and Rh(3+) at a concentration of 170 and 260 microg/l, respectively. After an exposure period of 6 weeks the mean Pt levels in bile, liver, kidney and intestine of the exposed eels ranged between 68 ng/g and 840 ng/g and the mean Rh levels between 35 ng/g and 155 ng/g whereas the PGM levels of the unexposed controls were below the detection limit of 50 ng/g for Pt and 5 ng/g for Rh. Rh was also taken up by gill and spleen. No PGM uptake was found for muscle and blood. The pattern of metal distribution within the eel differed between Pt and Rh and was dependent on the water type. Due to their accumulation capacity for PGM eels are suitable as accumulation indicators to detect PGM pollution in aquatic ecosystems.

The acanthocephalan Paratenuisentis ambiguus as a sensitive indicator of the precious metals Pt and Rh from automobile catalytic converters.

Recent studies revealed that intestinal acanthocephalans of fish can accumulate heavy metals to concentrations orders of magnitude higher than those in the host tissues or the aquatic environment. This significant heavy metal accumulation by acanthocephalans, even surpassing that of established free living accumulation bioindicators, encouraged us to study the bioavailability of the platinum-group-metals (PGM) Pt and Rh for parasites. These precious metals are used in catalytic converters of cars for exhaust gas purification in Europe since the early 1980s. In addition to the beneficial effect in reducing the emission of CHx, CO and NOx of cars there is an increasing emission of these metals. However, it still remains unclear if these elements become accumulated in the biosphere and whether they affect the health of organisms. The present study reveals that in European eels (Anguilla anguilla) naturally infected with the eoacanthocephalan parasite Paratenuisentis ambiguus and experimentally exposed to ground catalytic converter material, the parasites take up and accumulate the catalytic active metals Pt and Rh whereas in the examined host tissues we found no metal uptake. Compared with the PGM concentrations in the water the worms contained 1600 times higher Rh and 50 times higher Pt concentrations. Thus, the parasites can be used as sentinel organisms reflecting even very low levels of precious metals.

The intestinal parasite Pomphorhynchus laevis (Acanthocephala) from barbel as a bioindicator for metal pollution in the Danube River near Budapest, Hungary.

Concentrations of As, Al, Ag, Ba, Bi, Cd, Co, Cr, Cu, Fe, Ga, Mg, Mn, Ni, Pb, Sb, Sn, Sr, Tl, V and Zn were analyzed by inductively coupled mass spectrometry (ICP-MS) in the intestinal helminth Pomphorhynchus laevis and its host Barbus barbus. The fish were caught in the Danube river downstream of the city of Budapest (Hungary). Ten out of twenty one elements analyzed were found at higher concentrations in the acanthocephalan than in different tissues (muscle, intestine, liver and kidney) of barbel. Considering the fish tissues, most of the elements were present at highest concentrations in liver, followed by kidney, intestine and muscle. Spearman correlation analyses indicate that there is competition for metals between the parasites and the host. The negative relationships between parasite number and metal levels in organs of the barbel support this hypothesis. The bioconcentration factors for Ag, As, Ba, Bi, Cu, Ga, Mn, Pb, Sr, Tl, and Zn showed that the parasites concentrated metals to a higher degree than the fish tissues. They accumulated the metals As, Cd, Cu, Fe, Ni, Pb, Sr and Zn even better than established bioindicators such as the mussel Dreissena polymorpha as revealed by data from the literature. The results presented here emphasize that acanthocephalans of fish are very useful as sentinels for metal pollution in aquatic ecosystems. Ratio of metal concentrations in the parasites and the host tissues provide additional information. Not including acanthocephalans in accumulation bioindication studies with fishes (as still customarily done) may lead to false results.