Parasites alter food-web topology of a subarctic lake food web and its pelagic and benthic compartments.

We compared three sets of highly resolved food webs with and without parasites for a subarctic lake system corresponding to its pelagic and benthic compartments and the whole-lake food web. Key topological food-web metrics were calculated for each set of compartments to explore the role parasites play in food-web topology in these highly contrasting webs. After controlling for effects from differences in web size, we observed similar responses to the addition of parasites in both the pelagic and benthic compartments demonstrated by increases in trophic levels, linkage density, connectance, generality, and vulnerability despite the contrasting composition of free-living and parasitic species between the two compartments.

An examination of nervous system revealed unexpected immunoreactivity of both secretory apparatus and excretory canals in plerocercoids of two broad tapeworms (Cestoda: Diphyllobothriidea).

and are diphyllobothriidean tapeworms autochthonous to Europe. Their larval stages (plerocercoids) may seriously alter health of their intermediate fish hosts () or cause intestinal diphyllobothriosis of the final human host (). Despite numerous data on the internal structure of broad tapeworms, many aspects of the morphology and physiology related to host–parasite co-existence remain unclear for these 2 species.

Cercariae of a Bird Schistosome Follow a Similar Emergence Pattern under Different Subarctic Conditions: First Experimental Study.

The emergence of cercariae from infected mollusks is considered one of the most important adaptive strategies for maintaining the trematode life cycle. Short transmission opportunities of cercariae are often compensated by periodic daily rhythms in the cercarial release. However, there are virtually no data on the cercarial emergence of bird schistosomes from freshwater ecosystems in northern latitudes.

Somatic Dimorphism in Cercariae of a Bird Schistosome.

Phenotypic polymorphism is a commonly observed phenomenon in nature, but extremely rare in free-living stages of parasites. We describe a unique case of somatic polymorphism in conspecific cercariae of the bird schistosome sp. "peregra", in which two morphs, conspicuously different in their size, were released from a single snail.

Taxa-specific activity loss and mortality patterns in freshwater trematode cercariae under subarctic conditions.

Cercarial activity and survival are crucial traits for the transmission of trematodes. Temperature is particularly important, as faster depletion of limited cercarial energy reserves occurs at high temperatures. Seasonal climate conditions in high latitude regions may be challenging to complete trematode life cycle during the 6-month ice-free period, but temperature effects on the activity and survival of freshwater cercariae have not been previously identified.

Dietary immunostimulants reduced infectivity of Diplostomum spp. eye fluke in common carp, Cyprinus carpio L.

Juvenile common carp Cyprinus carpio L. (5.52 ± 1.

Cercarial behaviour alters the consumer functional response of three-spined sticklebacks.

Free-living parasite life stages may contribute substantially to ecosystem biomass and thus represent a significant source of energy flow when consumed by non-host organisms. However, ambient temperature and the predator's own infection status may modulate consumption rates towards parasite prey. We investigated the combined effects of temperature and predator infection status on the consumer functional response of three-spined sticklebacks towards the free-living cercariae stages of two common freshwater trematode parasites (Plagiorchis spp.

High parasite diversity in the amphipod in a subarctic lake.

Amphipods are often key species in aquatic food webs due to their functional roles in the ecosystem and as intermediate hosts for trophically transmitted parasites. Amphipods can also host many parasite species, yet few studies address the entire parasite community of a gammarid population, precluding a more dynamic understanding of the food web. We set out to identify and quantify the parasite community of to understand the contributions of the amphipod and its parasites to the Takvatn food web.

Species-specific patterns in cercarial emergence of Diplostomum spp. from snails Radix lagotis.

The cercarial emergence patterns of three species of Diplostomum (Diplostomum 'mergi', Diplostomum spathaceum and Diplostomum parviventosum) parasitizing freshwater first intermediate host Radix lagotis sampled in Most Lake, Czech Republic, were studied under various experimental conditions, i.e. field, laboratory and incubator, and seasons, i.

Temperature does not influence functional response of amphipods consuming different trematode prey.

Direct consumption on free-living cercariae stages of trematodes by non-host organisms interferes with trematode transmission and leads to reduced infections in the next suitable hosts. Consumer functional responses provide a useful tool to examine relationships between consumption rates and ecologically relevant prey densities, whilst also accounting for abiotic factors that likely influence consumption rates. We investigated how temperature influences the consumer functional response of the amphipod Gammarus lacustris towards the cercariae of three freshwater trematodes (Diplostomum, Apatemon and Trichobilharzia).

Confirmation of the presence of zoonotic Trichobilharzia franki following a human cercarial dermatitis outbreak in recreational water in Slovakia.

Human cercarial dermatitis is a parasitic disease that causes an allergic reaction in the skin (swimmer's itch) as a consequence of contact with cercariae of bird schistosomes present in water, mainly of the genus Trichobilharzia Skrjabin et Zakarow, 1920. The main objective of the study was to confirm the presence of the zoonotic disease agent following reports of human infections in recreational water in Slovakia. We identified two species of freshwater snails at Košice Lake, Radix auricularia (Linnaeus, 1758) and Physa acuta (Draparnaud, 1805).

Hidden parasite diversity in a European freshwater system.

Parasites comprise a huge part of the biodiversity on earth. However, on a local scale, not much is known about their diversity and community structure. Here, we assess the diversity of larval trematode communities in an interconnected freshwater system of the River Ruhr in Germany and analyse how the parasites are spatially and temporally distributed in the ecosystem.

Molecular analyses reveal high species diversity of trematodes in a sub-Arctic lake.

To identify trematode diversity and life-cycles in the sub-Arctic Lake Takvatn, Norway, we characterised 120 trematode isolates from mollusc first intermediate hosts, metacercariae from second intermediate host fishes and invertebrates, and adults from fish and invertebrate definitive hosts, using molecular techniques. Phylogenies based on nuclear and/or mtDNA revealed high species richness (24 species or species-level genetic lineages) and uncovered trematode diversity (16 putative new species) from five families typical in lake ecosystems (Allocreadiidae, Diplostomidae, Plagiorchiidae, Schistosomatidae and Strigeidae). Sampling potential invertebrate hosts allowed matching of sequence data for different stages, thus achieving molecular elucidation of trematode life-cycles and exploration of host-parasite interactions.

Eggs as a Suitable Tool for Species Diagnosis of Causative Agents of Human Diphyllobothriosis (Cestoda).

Background: Tapeworms of the order Diphyllobothriidea are parasites of tetrapods and several species may infect man and cause neglected human disease called diphyllobothriosis. Identification of human-infecting diphyllobothriid cestodes is difficult because of their morphological uniformity, which concerns also their eggs in stool samples.

Methods: In the present study, we analysed by far the largest dataset of more than 2,000 eggs of 8 species of diphyllobothriid cestodes that may infect humans, including the most frequent human parasites Diphyllobothrium latum, D.

The Early Worm Catches the Bird? Productivity and Patterns of Trichobilharzia szidati Cercarial Emission from Lymnaea stagnalis.

Digenean trematodes are common and abundant in aquatic habitats and their free-living larvae, the cercariae, have recently been recognized as important components of ecosystems in terms of comprising a significant proportion of biomass and in having a potentially strong influence on food web dynamics. One strategy to enhance their transmission success is to produce high numbers of cercariae which are available during the activity peak of the next host. In laboratory experiments with 13 Lymnaea stagnalis snails infected with Trichobilharzia szidati the average daily emergence rate per snail was determined as 2,621 cercariae, with a maximum of 29,560.

Integrative taxonomic approach to the cryptic diversity of Diplostomum spp. in lymnaeid snails from Europe with a focus on the 'Diplostomum mergi' species complex.

Background: Recent molecular studies have discovered substantial unrecognised diversity within the genus Diplostomum in fish populations in Europe and North America including three species complexes. However, data from the first intermediate host populations are virtually lacking. This study addresses the application of an integrative taxonomic approach to the cryptic species diversity of Diplostomum spp.

Estimating the risk of swimmer's itch in surface waters - A case study from Lake Baldeney, River Ruhr.

Swimmer's itch is a zoonotic disease caused by certain digenean trematodes, in Europe most noticeably by bird schistosomes of the genus Trichobilharzia. These parasites require waterfowl and aquatic snails as final and intermediate hosts, respectively, to complete their life cycle. Swimmer's itch occurs when the free-swimming larvae emitted from snails, the cercariae, accidentally infect humans.

Avian schistosomes and outbreaks of cercarial dermatitis.

Cercarial dermatitis (swimmer's itch) is a condition caused by infective larvae (cercariae) of a species-rich group of mammalian and avian schistosomes. Over the last decade, it has been reported in areas that previously had few or no cases of dermatitis and is thus considered an emerging disease. It is obvious that avian schistosomes are responsible for the majority of reported dermatitis outbreaks around the world, and thus they are the primary focus of this review.

A re-assessment of species diversity within the 'revolutum' group of Echinostoma Rudolphi, 1809 (Digenea: Echinostomatidae) in Europe.

Species of Echinostoma Rudolphi, 1809 (Digenea: Echinostomatidae) belonging to the 'revolutum' species complex were re-examined based on material gathered in an extensive sampling programme in eight countries in Europe. The morphology of the life-cycle stages was studied in naturally and experimentally infected snail and bird hosts. A review, with an updated synonymy, is presented for six European species, including one new to science, i.

Echinostoma 'revolutum' (Digenea: Echinostomatidae) species complex revisited: species delimitation based on novel molecular and morphological data gathered in Europe.

Background: The systematics of echinostomes within the so-called 'revolutum' group of the genus Echinostoma, which encompasses the type-species E. revolutum and a number of morphologically similar species, has long been controversial. Recent molecular studies indicate the existence of more species than previously considered valid, thus stressing the need for wider taxon sampling from natural host populations.

Morphological and molecular data for larval stages of four species of Petasiger Dietz, 1909 (Digenea: Echinostomatidae) with an updated key to the known cercariae from the Palaearctic.

Large-tailed echinostomatid cercariae of the genus Petasiger Dietz, 1909 (Digenea: Echinostomatidae) from the planorbid snails Gyraulus albus (Müller) and Planorbis planorbis (L.) collected in Germany and the Czech Republic and metacercariae from Gasterosteus aculeatus L. (Gasterosteiformes: Gasterosteidae) collected in Canada are characterised morphologically and molecularly.

Species diversity of Plagiorchis Lühe, 1899 (Digenea: Plagiorchiidae) in lymnaeid snails from freshwater ecosystems in central Europe revealed by molecules and morphology.

Larval stages of Plagiorchis spp. are both ubiquitous and ecologically important parasites in snail populations of freshwater ecosystems in Europe. However, difficulties in distinguishing the morphologically similar cercariae used for species identification, may lead to underestimation of species diversity.

New cryptic species of the 'revolutum' group of Echinostoma (Digenea: Echinostomatidae) revealed by molecular and morphological data.

Background: The digenean species of Echinostoma (Echinostomatidae) with 37 collar spines that comprise the so-called 'revolutum' species complex, qualify as cryptic due to the interspecific homogeneity of characters used to differentiate species. Only five species were considered valid in the most recent revision of the group but recent molecular studies have demonstrated a higher diversity within the group. In a study of the digeneans parasitising molluscs in central and northern Europe we found that Radix auricularia, R.

Swimmer's itch: etiology, impact, and risk factors in Europe.

This review summarizes current knowledge about the occurrence and distribution of swimmer's itch, with a focus on Europe. Although recent publications have reviewed the biology and systematics of bird schistosomes and their complex host-parasite interactions, the underlying ecological factors that create favorable conditions for the parasites and the way humans interact with infested water bodies require further attention. Relevant studies from the past decade were analyzed to reveal an almost complete set of ecological factors as a prerequisite for establishing the life cycle of bird schistosomes.

Molecular prospecting for European Diplostomum (Digenea: Diplostomidae) reveals cryptic diversity.

We believe this study is the first attempt to address molecular prospecting for species diversity of Diplostomum (Digenea: Diplostomidae) in Europe. A database linking sequences from the barcode region of the cytochrome c oxidase subunit 1 (cox1) mitochondrial gene and from the internal transcribed spacer cluster (ITS1-5.8S-ITS2) of the rRNA gene was generated for larval and adult parasites of snails, fish and gulls from central Europe.