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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.

The individual and combined effects of cadmium (Cd) and 3,3',4,4',5-pentachlorobiphenyl (PCB 126) on the antibody response of fish against metazoan parasites were tested. Eels experimentally infected with the swim bladder nematode Anguillicola crassus were exposed to sublethal concentrations of Cd and PCB 126. Cd was added to the water resulting in an effective concentration of 21.7 +/- 12.8 microg/l (mean +/- S.D.). PCB 126 was applied orally at a dose of approximately 100 ng PCB 126 per g body weight. At the end of the experiment, 76 days post-infection (p.i.), eels were found to be infected with 2-3 worms. Immunoblot analyses revealed that the body wall of adult worms was the most suitable crude antigen, and was subsequently used for an ELISA to evaluate the immune response of A. anguilla under various conditions. A significant increase of Anguillicola-specific antibodies in the peripheral blood was first detected 61 days p.i., indicating that it was not the invasive larvae but the adult worms which elicit the antibody response. The presence of Cd in the concentrations applied did not appear to modulate the production of antibodies. In contrast, the exposure to PCB 126 resulted in a complete suppression of the antibody response. A similar effect was also found for the combined exposure of the infected eels to Cd and PCB 126. A suppressed immune response, as demonstrated here, may be the reason why hosts exposed to environmental pollution became often much more easily infected than unexposed conspecifics.

Intention, Goal, Scope, Background: Following the introduction of automobile catalytic converters the platinum group metals (PGM) platinum (Pt), palladium (Pd) and rhodium (Rh) gain on increasing interest in environmental research as these metals are emitted with exhaust fumes into the environment. Consequently, elevated PGM levels were found in different environmental matrices such as road dusts, soils along heavily frequented roads, sediments of urban rivers etc. Accordingly, the effects of increasing PGM emissions on the biosphere are controversially discussed., Objective: This paper summarizes the present knowledge on the biological availability of PGM to plants and animals. As biological availability is one of the most decisive factors determining the toxicological potential of xenobiotics, this information is very important to evaluate the possible threat of the noble metals to ecosystems., Results and Discussion: The availability of soluble as well as particle bound PGM to terrestrial plants was demonstrated in several studies. Experimental investigations revealed uptake of Pt, Pd and Rh also by aquatic plants. Additionally, the biological availability of the noble metals for animals has been verified in experimental studies using soluble metal salts, catalytic converter model substances, sediments of urban rivers, road dust or tunnel dust as metal sources. These studies refer mainly to aquatic animals. Beside of free living organisms, in particular worms parasitizing fish demonstrated a high potential to accumulate PGM. This could be of great interest in respect of biomonitoring purposes. Generally, for plants as well as for animals Pd turns out to be the best available metal among the PGM. Compared to other heavy metals, the biological availability of PGM from road dust to zebra mussels (Dreissena polymorpha) ranged between that of Cd and Pb., Conclusion: Especially chronic effects of PGM on the biosphere can not be excluded due to (1) their cumulative increase in the environment, (2) their unexpected high biological availability and bioaccumulation and (3) their unknown toxicological and ecotoxicological potential. However, it appears that acute effects on ecosystems due to anthropogenic PGM emission are not likely., Recommendation and Outlook: Research on environmental PGM contamination of the biosphere, especially the fauna, and on long-term toxicity of low PGM concentrations is highly appreciated. These studies require very sensitive analytical techniques to determine PGM even in low sample amounts. Research has to be done in particular on reliable determination of (ultra) trace levels of Pd and Rh as the lack of data on these two metals is mainly due to analytical problems.

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.

Intestinal helminths of fish, especially the acanthocephalans, have become increasingly interesting as potential bioindicators for heavy metal contamination in aquatic habitats. Pomphorhynchus laevis from chub and barbel has been investigated frequently for its ability to take up and bioconcentrate metals within its body. This papers summarizes the present knowledge on P. laevis and its metal bioaccumulation properties in order to evaluate the applicability of species of the Pomphorhynchus genus as promising sentinels for heavy metals on a global scale.

Uninfected chub as well as fish experimentally infected with the acanthocephalan parasite Pomphorhynchus laevis were exposed to (210)Pb(2+) for up to 38 days and the uptake and distribution of lead within different fish organs and the parasites was determined at various time points. Highest metal concentrations were detected in the acanthocephalans, followed by intestine, bile, liver, gill and muscle of the fish host. Infected chub had significantly lower (210)Pb levels in the gills on day 17 (P< or =0.01), in the bile on day 24 (P< or =0.05) and in the gills as well as in the intestine on day 38 compared with uninfected fish. A subsequent polynomial regression revealed that lead levels for the infected fish ranged below the levels determined for uninfected fish during most of the exposure period. This is the first proof that P. laevis reduces lead levels in the bile thereby diminishing or even impeding the hepatic intestinal cycling of lead, which may reduce the amount of metals available for the fish organs. This is especially important for ecotoxicological research. For example, organisms used as accumulation indicators may erroneously indicate low levels of pollution if they are infected with parasites which alter their pollutant uptake mechanisms. Additionally, the results gave further experimental evidence for acanthocephalans as accumulation indicators for metals.

Concentrations of lead, determined by electrothermal atomic absorption spectrometry, were compared between the cestodes Hymenolepis diminuta and Taenia taeniaeformis and its host rat (Rattus norvegicus). Rats were sampled at 2 sites, which differed in respect to lead pollution as quantified from road dust, adjacent to the city of Cairo, Egypt. Comparing lead levels among host tissues and the parasites the significantly highest accumulation was found in H. diminuta, followed by rat kidney and larvae of T. taeniaeformis. Calculation of bioconcentration factors showed that H. diminuta contained 36-, 29-, 6- and 6-fold higher lead levels than intestinal wall, liver, kidney and larvae of T. taeniaeformis, at the more polluted site. At the less contaminated site lead bioconcentration factors for H. diminuta were found to be 87, 87 and 11 referred to intestine, liver and kidney of the host. Due to a high variability of the lead concentrations in H. diminuta it was not possible to indicate differences in metal pollution between both sampling sites. This variability may be influenced by different age structures of cestode infrapopulations. It is likely that younger worms contain lower metal levels than older worms due to a shorter exposure period. Thus, it is necessary to standardize the sampling of worms which should be used for indication purposes. Due to a lack of adequate sentinel species in terrestrial habitats more studies are required to validate and standardize the use of helminths as accumulation bioindicators in order to obtain mean values with low standard deviations. The host-parasite system rat-H. diminuta appears to be a useful and promising bioindication system at least for lead in urban ecosystems as rats as well as the tapeworm are globally distributed and easily accessible.

Chub experimentally infected with the acanthocephalan parasite Pomphorhynchus laevis were exposed to 0.01 mg l(-1) Pb(2+) over 5 weeks. Lead was rapidly accumulated in the intestinal worms reaching a steady-state concentration after 4 weeks. This concentration was significantly greater than in the host muscle, liver and intestine and more than 9,000 times higher than the exposure concentration. Lead accumulation in P. laevis increased at a higher exposure concentration but was not correlated with either parasite intensity or with pooled or individual worm weight. The highest lead concentrations were recorded in those specimen of P. laevis that were attached in the posterior intestine. Interestingly, parasitised chub accumulated less lead in their own tissues than uninfected conspecifics. A mechanism of lead uptake by P. laevis and the application of acanthocephalans as accumulation indicators of metal pollution is discussed.

Intestinal helminths of fish are of increasing interest as potential bioindicators for heavy metal contamination in aquatic habitats. Among these parasites cestodes and acanthocephalans in particular have an enormous heavy metal accumulation capacity exceeding that of established free living sentinels. Metal concentrations several thousand times higher in acanthocephalans than in host tissues were described from field and laboratory studies. Whereas larval stages inside their intermediate hosts are not able to take up high quantities of metals, young worms begin to take up metals immediately after infection of the final host. After four to five weeks of exposure, the parasites reach a steady-state concentration orders of magnitude higher than the ambient water level. Thus, acanthocephalans are not only very effective in taking up metals, but they can also respond very rapidly to changes in environmental exposure. The mechanism which enable acanthocephalans to take up metals from the intestinal lumen of the host appears to be based on the presence of bile acids, which form organo-metallic complexes that are easily absorbed by the worms due to their lipophilicity. Investigations of the environmental conditions affecting metal uptake have shown that the parasites are more consistent and reliable indicators for metal pollution than the host tissues as metal levels of the latter are much more dependent on the water chemistry. Thus, after some years of research on the uptake of metals by acanthocephalans and on the factors affecting metal accumulation in intestinal parasites it should be asked if acanthocephalans meet the criteria commonly accepted for sentinels. If parasites can be considered as promising sentinels, we need reasons for the establishment of 'new' indicators. Therefore, this review summarises the present knowledge about parasites as bioindicators and compares the accumulation properties of parasites and established free living indicators. Finally, this review presents possible answers to the question why it could be advantageous to have new and even more sensitive indicators for environmental monitoring purposes.

This paper describes two approaches to evaluate the use of fish macroparasites as bioindicators of heavy metal pollution at selected river stretches in Austria. Firstly changes in the diversity and richness of endoparasites of the cyprinid barbel, Barbrus barbuls (L.), were tested in relation to heavy metal contents in the aquatic system. Secondly, the bioaccumulation potential of cadmium, lead and zinc was assessed in the acanthocephalan, Pomphorhynchus laevis (Miller, 1776), and compared with that in the muscle, liver and intestine of its barbel host. The present results indicated that in order to validate the role of parasite community patterns related to heavy metal pollution, more investigations on food web dynamics, interelationships between parasites and the presence/absence of intermediate hosts will be essential. Heavy metal concentrations differed significantly between the organs of barbel and P. laevis (P=0.001) with levels up to 2860 fold in the parasite. The high level of heavy metal accumulation in P. laevis compared with that in its barbel host, suggests that despite variability in the parasite infrapopulation, host mobility and feeding behaviour, P. laevis is a most sensitive indicator of heavy metals in aquatic ecosystems.

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.

Investigations on the bioaccumulation of the platinum group metals (PGM) Pt, Pd and Rh in aquatic organisms are of growing interest in environmental research due to the increasing emission of these metals by motor vehicles with catalytic converters. Until now, nothing is known about the possible influence of complexing agents on the bioaccumulation capacity of these precious metals. According to the partition coefficient between 1-octanol and water (POW) as a measure of bioaccumulation, in this study a simple shaking method was performed in order to investigate the effects of different complexing agents (-methionine, thio urea, EDTA, humic substances, bile compounds) on the octanol solubility of the PGM. The results demonstrated a significant influence of all agents used. -Methionine and thio urea decreased the lipid solubility. In contrast, the presence of EDTA, humic substances and especially bile caused a higher transfer of metals in the octanol phase. For most complexing agents tested, the transfer of Pd to the lipid phase was significantly higher compared with Rh and Pt, except for bile acid where the highest octanol solubility was found for Pt. Recent experimental results on PGM accumulation in zebra mussels confirm a high bioaccumulation of Pd which could be predicted from the lipid solubility.

The uptake and bioaccumulation of 15 road dust metals by the zebra mussel (Dreissena polymorpha) were investigated in laboratory exposure studies with emphasis on the traffic-related platinum-group elements (PGEs) palladium (Pd), platinum (Pt), and rhodium (Rh). The biological availability of the metals may depend on water characteristics, so the mussels were maintained in two types of water: nonchlorinated tap water and humic water of a bog lake, both of which contained dust of a moderately frequented road. After an exposure period of 26 weeks, soft tissues of the mussels were freeze-dried and analyzed for the metals. The metal concentrations in the mussel soft tissue ranged from several hundred micrograms per gram (e.g., for iron [Fe]) to less than 10 ng/g (for PGEs). Metal uptake from the road dust by the mussels was found for the PGEs and silver (Ag), bismuth (Bi), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), Fe, lead (Pb), and antimony (Sb). After maintenance of mussels in road dust-contaminated tap water, bioaccumulation factors (BAF = (C(exposed mussels) - C(control mussels))/C(total metal, water), where c is concentration) decreased in the following order: Cu > Cd > Ag > Pd > Sb > Pb > Fe > Pt > Rh. The biological availability of most metals was enhanced by humic water as compared to tap water. Our results show a hitherto unrecognized high availability of Pd for the mussels. Thus, this metal should be monitored more intensively in the environment to assess its distribution in the biosphere.

It recently became clear that acanthocephalans parasitizing mammals can bioconcentrate several heavy metals to conspicuously higher concentrations than the tissues of their definitive hosts. As cestodes are more abundant in terrestrial animals than acanthocephalans, and thus potentially more useful in attempts toward passive as well as active biomonitoring, a very common tapeworm and its synanthropic mammalian host were selected for the present study. The tapeworm Hymenolepis diminuta and experimentally infected male Wistar rats of the CD-M-strain were investigated with respect to their lead accumulation. The worms were allowed to grow up for five weeks post infection followed by a five weeks oral lead exposure of the rats. After the exposure period the rats were killed and the metal levels were determined in muscle, liver, intestine, testes and kidney of the rats as well as in the parasites. Lead concentrations were found to be 17 times higher in the cestodes than in kidney, whereas metal levels in all other host tissues were below the detection limit. Thus, this study reveals that lead accumulation also occurs in cestodes parasitizing mammals. Due to a lack of adequate sentinel species in terrestrial habitats the host-parasite-system rat-H. diminuta appears to be a useful and promising bioindication system especially in urban ecosystems.

Following the introduction of automobile catalysts in the middle of the Eighties in Germany there is an increasing emission of the platinum-group-metals (PGM) platinum (Pt), palladium (Pd) and rhodium (Rh). Still, it remains unclear if these metals are bioavailable for aquatic animals and to which extent they accumulate in the aquatic biosphere. Zebra mussels (Dreissena polymorpha) were maintained in water containing road dust at a concentration of 1 kg/10 l. Following an exposure period of 26 weeks, soft tissues of the mussels were analysed applying adsorptive cathodic stripping voltammetry (ACSV) for the determination of Pt and Rh and total-reflection X-ray fluorescence analysis after co-precipitation of Pd with mercury. This experiment revealed for the first time that all the three catalyst emitted metals were accumulated by mussels. The bioaccumulation increased in the following manner: Rh < Pt < Pd. Thus, the application of sentinel organisms in combination with modern trace analytical procedures in environmental impact studies does allow an assessment of the distribution and the degree of bioaccumulation of PGM in the environment, which is highly appreciated.

Concentrations of various essential and toxic elements (Ba, Ca, Co, Cu, Fe, Mg, Mn, Sr, Zn and Al, Ag, Cd, Cr, Ni, Pb, Tl) were analysed by inductively coupled plasma mass spectrometry in the acanthocephalan Acanthocephalus lucii and in different tissues of its host Perca fluviatilis. Nearly all the elements were found in significantly higher concentrations in the acanthocephalan than in the host tissues. Spearman correlation analysis revealed several strong inter-element associations within the organs of perch and within the parasites. Furthermore, statistical analysis revealed different competitive interactions. The concentrations of several essential elements (Ba, Ca, Fe, Mn, Sr and Zn) within the parasites decreased with an increasing number or weight of worms inside the intestine of the host. Additionally, the levels of some elements in the perch liver were negatively correlated with the weight of A. lucii in the intestine. Thus, it emerged that not only is there competition for essential elements between acanthocephalans inside the gut but there is also competition for these elements between the host and its parasites.

The impact of an infection with the acanthocephalan Moniliformis moniliformis and a simultaneous Cd-exposure on the stress hormone levels of rats was studied. Immediately after the application of cadmium to some rats, cortisol levels in all groups of rats, as quantified by radioimmunoassay (RIA), significantly increased. However, infections with M. moniliformis as well as the uptake of Cd reduced significantly the cortisol release compared to untreated controls. While catecholamine concentrations, as determined by high-performance liquid chromatography (HPLC), showed no clear tendency during the experimental period, the ratio of C(adrenaline)/C(noradrenaline) in the controls showed the significantly lowest value of all four groups after killing the animals. Thus, the acanthocephalan infection as well as the Cd-exposure and the combination of both treatments affect hormone homeostasis in the rats which probably lead to negative effects on the health of the rat. Therefore parasite infections must be carefully considered in environmental impact studies, as an important factor affecting the host's health.

The purpose of this study was to determine under laboratory conditions over a period of 311 days if infection with the nematode Anguillicola crassus induces stress in European eels (Anguilla anguilla), and stimulates the endocrine stress axis as measured by serum cortisol levels. Eels were experimentally infected with 3rd-stage larvae (L3) in different doses to simulate natural conditions with varying infection pressures. Blood samples were drawn from the caudal vein every 2 weeks and serum cortisol concentrations were determined by radioimmunoassay (RIA). The results showed that the application of L3 resulted in a significant increase in the cortisol levels. The period of time at which elevated cortisol values were observed was consistent with the time of larval development and the appearance of adult A. crassus. Thus, there is a stress response to the larval and young adult stages, but no chronic response to older adults. Therefore, it is likely that infection of eels under natural conditions especially with a high number of larvae may be a considerable stressor, in combination with different environmental factors like water temperature, pH, oxygen concentration, pollution and interindividual relationships.

European eels (Anguilla anguilla) from 2 sampling sites on the Rhine river (near Karlsruhe and near Worms) were investigated with respect to their parasite communities. Nine different metazoan species were found to live in and on the eels. The highest number of species was recorded from the intestine, which contained up to 6 different helminths. Among these, acanthocephalans were the most prevalent worms with the eel-specific parasite Paratenuisentis ambiguus as the dominant species of the intestinal component communities at both sites. Comparing the intestinal parasites from eels caught near Karlsruhe with those from Worms, the acanthocephalans showed a significantly lower abundance at Worms. A significantly lower mean number of intestinal helminth species as well as a significantly lower Brillouin's Index was found at Worms compared with Karlsruhe. This difference could be related to the abundance of the respective intermediate crustacean hosts. At the sampling site Worms the amphipod Corophium curvispinum was the dominant crustacean. Additionally, only the isopod Jaera istri and the amphipod Dikerogammarus villosus were found. All these crustacean species have only recently colonized the Rhine river system via the Main-Danube canal, built in the early 1990s. They are not known to act as intermediate hosts for any of the acanthocephalans found in the eels. The site near Karlsruhe exhibited a higher crustacean diversity, including Asellus aquaticus and different species of the genus Gammarus, which are all known intermediate hosts for the acanthocephalans found. Therefore, changes of eel parasite diversity can be correlated with the appearance of invading crustacean species (neozoans).

Following the introduction of automobile catalysts in the middle of the 1980s in Germany there is an increasing emission of the platinum-group-metals platinum, palladium (Pd) and rhodium. Still, it remains unclear if these metals are bioavailable for aquatic animals and to which extent they become accumulated by the aquatic biosphere. Because of analytical problems in detecting Pd in small biological samples the present investigation concentrates on the bioavailability of this metal. To answer the question of a Pd uptake by aquatic organisms experimental studies were conducted with European eels maintained in water containing road dust at a concentration of 10 kg/100 l. Following an exposure period of four weeks, samples of liver and kidney were analysed by total-reflection X-ray fluorescence analysis after co-precipitation of Pd with mercury. These experiments revealed an uptake of traffic related Pd by European eels which showed a mean liver Pd concentration of 0.18 +/- 0.05 ng/g (wet wt.), whereas the Pd concentration in the kidney ranged below the detection limit. Thus, in this study we can demonstrate for the first time that automobile catalyst emitted Pd is bioavailable for aquatic animals.

It recently became clear that adult eo- and palaeacanthocephalans parasitizing fish can bioconcentrate several heavy metals to significantly higher concentrations than the tissues of their definitive hosts. Following this discovery the lead accumulation of the archiacanthocephalan Moniliformis moniliformis was investigated using experimentally infected male Wistar rats of the CD-M-strain. The worms were allowed to grow up for 4 weeks post-infection followed by a 3 weeks oral lead exposure of the rats. After the exposure period the rats were killed and the metal levels were determined in muscle, liver, intestine and kidney of the rats as well as in different organs of female and male acanthocephalans. Lead concentrations were found to be highest in female M. moniliformis followed by the kidneys of the rats. Male worms contained approximately the same lead concentration as the hosts' kidneys. Lead analysis of the worms' organs revealed the highest lead concentration in the eggs of female acanthocephalans, followed by the cement gland of male Worms. Whilst the lead burden of the presoma was higher than that detected in the kidneys of the rats, the lead content of the metasoma was even lower than in the kidneys. A lead uptake of M. moniliformis from the intestinal lumen of the host became apparent as the faeces of infected rats contained significantly less lead compared to the uninfected conspecifics. Thus, this study reveals that lead accumulation also occurs in archiacanthocephalans parasitizing mammals. But the degree of metal bioconcentration is considerably lower compared to eo- and palaeacanthocephalans in fish. Anyway, due to a lack of adequate sentinel species in terrestrial biotopes the host-parasite system rat M. moniliformis appears to be a useful and promising bioindication system especially in urban ecosystems in temperate regions.

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.

The accumulation of cadmium in Moniliformis moniliformis parasitizing experimentally infected rats that had been orally exposed to cadmium was investigated in this study. Cadmium accumulation in the helminth and in different tissues of the host was determined using electrothermal atomic absorption spectrometry (AAS) after a 3-week period of exposure. The mean cadmium concentration measured in M. moniliformis was 5.8 microg g(-1) wet weight, which was 20, 23, and 119 times higher than that determined in the kidney, liver, and intestine of the host, respectively. Although female worms accumulated higher amounts of cadmium than did males, no tendency emerged between the cadmium concentration and the weight of individual acanthocephalans. This study reveals that cadmium accumulation also occurs in archiacanthocephalans, but to a lesser degree than in palaeacanthocephalans parasitizing fish. Due to its cadmium-accumulation capacity, M. moniliformis might be used as a highly sensitive free-living bioindicator in terrestrial and urban ecosystems.

The development of Anguillicola crassus in experimentally infected Ariosoma balearicum (Anguilloidea, Congridae) kept in seawater was studied in the laboratory. In parallel trials the effect of water salinity on the development of larval A. crassus in European eels Anguilla anguilla was also investigated using eels kept in seawater of a salinity of 34 per thousand. Both eel species were orally inoculated with L3 larvae of A. crassus and then maintained for up to 3 mo at 18 degrees C in seawater. 110 d post infection, no adult but larval (L3 and L4) stages of A. crassus were detected in the swimbladder wall of Balearic congers, although this period of time was sufficient for the parasites to develop to the adult stage in European eel kept in seawater. The results presented suggest that the definitive host specificity of A. crassus comprises species of the family Anguillidae (i.e. the genus Anguilla), but not members of the Congridae. Theoretically however, A. balearicum might serve as a metaparatenic host. Factors determining the definitive host range of A. crassus remain to be elucidated. Water salinity does not seem to act as a factor affecting definitive host specificity once the parasite has become ingested by the eel.

Aqueous lead exposure of chub (Leuciscus cephalus) experimentally infected with the parasite Pomphorhynchus laevis resulted in a rapid accumulation of this metal in the intestinal acanthocephalans, reaching concentrations which were significantly greater than in the host muscle, liver, and intestine and approximately 1000 times higher than the exposure con centration. Parasitized chub accumulated significantly less lead in their intestinal wall than their uninfected conspecifics (Mann-Whitney U test, P

A total of 121 European eels (Anguilla anguilla) from 2 sampling sites on the River Rhine were investigated in respect of their parasite communities. Special attention was given to the swim bladders, intestines, gills and fins of the fish. Twelve different parasite species were found to live in and on the eels. Data from each sampling site were kept separate. Parasites found in descending order of prevalence were: Anguillicola crassus, Trypanosoma granulosum, Myxobolus sp., Paratenuisentis ambiguus, Pseudodactylogyrus sp., Bothriocephalus claviceps, Myxidium giardi, Pomphorhynchus laevis, Trichodina sp., Raphidascaris acus, Acanthocephalus lucii and Acanthocephalus anguillae. Significantly different prevalences were reported for L3 larvae of A. crassus, adult P. ambiguus, B. claviceps and Myxobolus sp. at the 2 sampling sites. The highest number of parasite species was recorded from the intestine, which contained up to 6 different helminths. The coexistence of the acanthocephalans P. laevis and P. ambiguus, which showed clear patterns of distribution within the intestine of the respective hosts, was reported for the first time. Up to 3 different helminth species were found in the intestine of individual fish. Among those, acanthocephalans were the most prevalent worms with the eel-specific parasite P. ambiguus as the dominant species not only of the intestinal but also of the total component communities. Both infra and component communities exhibited low diversity and were dominated by this single species. The evenness reached only approximately 50% or less and it remained unclear why the helminth communities of the eels from the River Rhine with its huge catchment area exhibit such a low parasite diversity and high dominance.

The effect of salinity and the mode of application (oral versus aqueous) on the lead accumulation in different tissues of the fish host eel (Anguilla anguilla) and its parasites Anguillicola crassus (Nematoda) and Paratenuisentis ambiguus (Acanthocephala) was investigated. Waterborne as well as dietary lead exposure caused an increase in the metal levels of different eel tissues and the parasites. The mode of lead application had a significant influence on the distribution of lead in the fish tissues. No significant difference on the lead concentration due to water salinity was found for the fish tissues. Among the analyzed tissues and helminths, the intestinal acanthocephalan P. ambiguus contained the significantly highest amounts of lead, which were affected by neither the mode of application nor the water salinity. In contrast, the lead level of the nematode A. crassus dwelling in the swim bladder of eels was even below the levels detected for host liver, intestine, and bile. Thus, depending on the mode of lead application, the resulting metal concentrations were approximately 20 to 2,000 times higher in P. ambiguus than in A. crassus. These differences may be due to the different microhabitats and nutrient uptake mechanisms of both parasite species. This study presents important new facts for the use of intestinal fish parasites as biological indicators for water quality, not only in freshwater, but also in marine and estuarine ecosystems. The combination of the results obtained from the host and the parasites could reveal a more detailed tool to ascertain the source of an environmental contamination than a study based on a single species.http://link.springer-ny. com/link/service/journals/00244/bibs/37n2p190.html

Parasites are attracting increasing interest from parasite ecologists as potential indicators of environmental quality because of the variety of ways in which they respond to anthropogenic pollution. However, until recently, little was known about the accumulation of toxins within parasites. Certain parasites, particularly intestinal acanthocephalans and cestodes of fish, can accumulate heavy metals at concentrations that are orders of magnitude higher than those in the host tissues or the environment. In this review, Bernd Sures, Roy Siddall and Horst Taraschewski discuss the recently described phenomenon of conspicuous metal accumulation by parasites and how this might be applied to environmental monitoring. They also suggest how environmental science and parasitology might profit from each other in the near future.

The uptake of lead by cystacanths of the acanthocephalan Pomphorhynchus laevis in naturally infected amphipods, Gammarus pulex, and by immature parasites in experimentally infected fish, Leuciscus cephalus, was examined following 3-week experimental exposures (0.01 and 0.1 mg l(-1) Pb2+). Both G. pulex and the cystacanths of P. laevis accumulated lead but concentrations in the parasites were lower than in the host tissues at the low lead dose and significantly lower at the high dose. P. laevis from chub exposed to 0.01 mg l(-1) lead contained significantly more of the metal than the tissues of their host. Interestingly, there was an increase in the mean lead levels in the parasites from the control chubs which was concurrent with a decrease in host tissue concentrations. The results of this experimental study therefore confirm previous suggestions that heavy metals are predominantly accumulated by acanthocephalans inside the fish definitive host and not by cystacanths in the haemocoel of the amphipod intermediate host. The microhabitat of the parasite is therefore of primary importance rather than its developmental stage. Furthermore, metal concentrations in adult acanthocephalans will respond rapidly to changes in environmental exposure of their hosts.

The effect of low water temperatures on the development and viability of larval and adult Anguillicola crassus (Nematoda) in the final host Anguilla anguilla was studied. European eels were experimentally infected with A. crassus and then maintained for 4 mo at 4, 9, 10, and 19 degrees C. Larval development showed a temperature-dependent pattern and was significantly retarded at low temperatures. Third-stage larvae survived a 4 mo period at 4 degrees C without being affected, although they were not able to invade the swimbladder wall at this temperature. In contrast, adult worms were severely harmed during a 4 mo period at 4 degrees C, as reflected by increased mortality and decreased growth and reproductivity as compared to the worms maintained for the same period at 18 degrees C. Starvation for the eels at 4 mo at 19 degrees C did not affect the development and growth of the nematode. The experimentally obtained results support the hypothesis that the spread of A. crassus in boreal regions, e.g. Northern Europe, is restricted by the natural ambient temperature regimes.

Intestinal helminths of fish caught from freshwater and brackish water biotopes throughout Europe were analysed by electrothermal atomic absorption spectrometry for their heavy metal (Pb and Cd) levels. The metal concentrations of the parasites were compared to those of different organs (muscle, liver, intestine) of the fish hosts and to those detected in the whole bodies of the respective intermediate hosts. The three acanthocephalan species analysed contained very high amounts of Pb and Cd. The lead level of Pomphorhynchus laevis was up to 2700 times higher and the cadmium concentration was approximately 500 times higher than the muscle of chub, its host. Concurrent analysis of larval acanthocephalans in the crustacean intermediate host indicated that the bioconcentration of heavy metals by these parasites occurs only in the final host. In two species of cestodes accumulation of metals was also recorded although the degree of bioconcentration was somewhat lower. Nevertheless, Monobothrium wageneri contained 75 times more Pb and 43 times more Cd than the muscle of its host, the tench. In contrast, no bioconcentration of heavy metals was detected in the swimbladder nematode Anguillicola crassus. It contained less lead than the muscle of its final host, the eel. In one biotope the concentration of 18 elements was compared between the whole soft tissues of the zebra mussel, Dreissena polymorpha, the parasite Acanthocephalus lucii and its final host, perch. The acanthocephalan accumulated most of the elements to considerably higher concentrations than the zebra mussel, which has been considered an effective bioindicator of heavy metals. The sessile nature of the zebra mussel may allow a better identification of small-scale local differences in environmental heavy metal contamination. However, acanthocephalan parasites will provide an ecologically-important index of average exposure of their mobile fish host to biologically-available metals within its natural range.

The adult cestodes Monobothrium wageneri and Bothriocephalus scorpii from the intestines of their respective final hosts, tench (Tinca tinca) caught in the river Ruhr, Germany, and turbot (Scophthalmus maximus) collected from two sampling sites on the coast of Gdansk, Poland, were analyzed for lead and cadmium by atomic absorption spectrometry. Both cestode species contained significantly higher cadmium contents than did the muscle, liver, and intestine of their fish hosts. Whereas M. wageneri also contained several times more lead than did the organs of tench, B. scorpii showed nearly the same lead burden as did the liver and intestine of turbot. Posterior sections of B. scorpii comprising gravid proglottids contained significantly higher concentrations of lead and cadmium than did the anterior proglottids.

Adults of Pomphorhynchus laevis and Acanthocephalus lucii were analyzed for cadmium by atomic absorption spectrometry. Their cadmium concentrations were compared with those found in different tissues (muscle, liver, and intestine) of their final hosts the chub and perch. Additionally, the cadmium and lead concentrations in larvae of A. lucii and their intermediate host Asellus aquaticus were determined. Regarding the adult acanthocephalans, the parasites showed several times more cadmium than did the tissues of their fish hosts. In contrast to this obvious accumulation capacity of adult A. lucii, the larvae contained less cadmium than did their crustacean host. Thus, the cadmium concentration in the larval stages was nearly 180 times lower than that measured in the adult worms. According to the present results, it appears that the heavy metals cadmium and lead are predominantly accumulated by the adult acanthocephalans inside the fish gut and not by the larvae inside the hemocoel of the crustaceans.

Adults of Pomphorhynchus laevis were collected from the intestines of 10 chubs (Leuciscus cephalus) from the river Ruhr near Bochum, Germany. The acanthocephalans and various tissues of the fish (muscle, liver, and intestine) were analyzed for lead with electrothermal atomic absorption spectrometry. The mean lead level in the parasite was 54 micrograms/g wet weight, which was 284 times more than in the host intestine, 771 times more than in host liver, and 2,700 times more than in host muscle. Thus, P. laevis may serve as a very sensitive bioindicator for the presence of biologically available lead in aquatic ecosystems.