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Dispersal is ubiquitous in animals, shaping natural populations' ecological and evolutionary patterns. In freshwater ecosystems, the drift or downstream movement of animals (e.g., macroinvertebrates) carried by water current might be modulated by parasites and their seasonal occurrence. However, most studies on parasite modulation of host drifting behavior have focused on acanthocephalans, and other parasites like microsporidians have been largely neglected. The present study provides new insight into seasonal and dial amphipod drift modulation by microsporidian parasites. Experiments employing drift nets took place in a German stream in October 2021, April, and July 2022. Ten microsporidians were identified, expanding current knowledge of host-parasite interaction in Gammarus pulex clade E by five interactions. The prevalence and composition of microsporidian parasites varied seasonally, between day and night, and between drifted and stationary amphipods. Prevalence was generally higher in drifted amphipods than stationary ones. These changes were linked to host size and population dynamics. However, in two parasites, the prevalence was highest during the daytime suggesting changes in host phototaxis likely related to the parasite’s mode of transmission. Alterations in drifting behavior may have important implications for amphipods population dynamics and microsporidians' dispersal. The underlying mechanisms are more complex than previously thought.

Ecotoxicological effects of photolytic degradation mixtures of the two brominated flame retardants PolymericFR and Tetrabromobisphenol A-bis (2,3-dibrom-2-methyl-propyl) Ether (TBBPA-BDBMPE) have been studied in vitro and in vivo. Both substances were experimentally degraded separately by exposure to artificial UV-light and the resulting degradation mixtures from different time points during the UV-exposure were applied in ecotoxicological tests. The in vitro investigation showed no effects of the degraded flame retardants on the estrogenic and androgenic receptors via the CALUX (chemically activated luciferase gene expression) assay. Short-term exposures (up to 96 h) of Lumbriculus variegatus lead to temporary physiological reactions of the annelid. The exposure to degraded PolymericFR lead to an increased activity of Catalase, while the degradation mixture of TBBPA-BDBMPE caused increases of Glutathione-S-transferase and Acetylcholine esterase activities. Following a chronic exposure (28 d) of L. variegatus, no effects on the growth, reproduction, fragmentation and energy storage of the annelid were detected. The results indicate that the experimental degradation of the two flame retardants causes changes in their ecotoxicological potential. This might lead to acute physiological effects on aquatic annelids, which, however, do not affect the animals chronically according to our results.

Supplementary Material. (PDF 314 kb)

Sampling locations; Names and GPS coordinates of sampling sites. (PDF 180Â kb)

Genetic data of host amphipod species. Given are the number of specimens (N), number of haplotypes (H), haplotype diversity (Hd) and genetic diversity (π); sd = standard deviation. (PDF 262 kb)

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 × 15–18 μ. 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 also 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.

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<>

Parasites are attracting increasing interest from parasite ecologists as potential indicators of environmental quality due to the variety of ways in which they respond to anthropogenic pollution. In environmental impact studies certain organisms provide valuable information about the chemical state of their environment not through their presence or absence but instead through their ability to concentrate environmental toxins within their tissues. Free living invertebrates, notably bivalve molluscs, are commonly employed in this role as `sentinel organisms' to monitor the concentrations of bioavailable metals in aquatic ecosystems. Also certain parasites, particularly intestinal acanthocephalans of fish, can accumulate heavy metals to concentrations orders of magnitude higher than those in the host tissues or the environment. The comparison of metal accumulation capacities between acanthocephalans and established free living sentinel organisms revealed significantly higher concentrations of several elements in Acanthocephalus lucii (Müller) than in the Zebra mussel Dreissena polymorpha (Pallas) which is a commonly used bioindicating organism in Europe. In contrast to the high heavy metal concentrations recorded in adult acanthocephalans, the larval stages in their respective crustacean intermediate hosts show little tendency to accumulate metals. A number of experimental studies demonstrate a clear time dependent accumulation of lead for acanthocephalans in their final hosts. These investigations provide evidence that the extremely high metal concentrations in intestinal acanthocephalans of fish are not the result of a slow process of accumulation but instead a relatively rapid uptake to a steady-state level. Thus, metal concentrations in adult acanthocephalans respond rapidly to changes in environmental exposure of their hosts. The value of parasites for environmental monitoring will be discussed in detail in the present article.

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 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.

Duisburg, Essen, Univ., Diss., 2014 Die Ergebnisse der vorliegenden Dissertation erweitern das Wissen über das Wirt-Parasit-Verhältnis von Aalen (Anguilla) und parasitischen Nematoden der Gattung Anguillicola im Allgemeinen, als auch über A. novaezelandiae im Besonderen. Unterschiede im natürlichen Vorkommen von A. crassus und A. novaezelandiae wurden aufgezeigt und larvale Stadien der letztgenannten Art erstmals in Neuseeland untersucht. Durch die experimentelle Infektion des Europäischen Aals mit A. novaezelandiae konnte die Art mit Studien über A. crassus verglichen und grundlegende Unterschiede entdeckt werden. Die Effekte einer Anguillicola sp. Infektion auf die hsp70-Reaktion des Aals wurde erstmals untersucht. Durch A. novaezelandiae und A. crassus induzierte Stresslevel waren vergleichbar. Eine Infektion des Aals mit beiden Parasitenarten wurde durchgeführt und die Hypothese einer Hybridisierung getestet. Zusammengefasst zeigen die Ergebnisse, dass man das Wissen über eine einzelne Art nicht einfach auf andere Arten der gleichen Gattung übertragen kann. Weitere Forschungsarbeiten sind nötig, um Anguillicola und seinen Aalwirt besser verstehen zu können. Das Anguilla-Anguillicola-System stellt ein exzellentes Beispiel für die Auswirkungen des Welthandels auf endemische Arten und deren Schädigung durch invasiver Parasiten dar. Zukünftig sollte der Aalhandel, insbesondere mit lebenden Aalen, viel vorsichtiger gehandhabt werden, um eine weitere Ausbreitung von Anguillicola Arten zu vermeiden.