Effects of the acanthocephalanPolymorphus minutusand the microsporidianDictyocoela duebenumon energy reserves and stress response of cadmium exposedGammarus fossarum
Abstract:Amphipods are commonly parasitized by acanthocephalans and microsporidians and co-infections are found frequently. Both groups of parasites are known to have severe effects on their host. For example, microsporidians can modify host sex ratio and acanthocephalans can manipulate the behavior of the amphipod to promote transmission to the final host. These effects influence host metabolism in general and will also affect the ability of amphipods to cope with additional stressors such as environmental pollution, … Show more
“…More recent publications referring to these three types were based on COI, but the sampling remained restricted to or centred around Germany 20,55,56,63 . Our study shows that samples from these studies 20,55,56,63 are associated exclusively with one or two BINs per type (type A: ADH0573 20 ; type B: ACG7784 and ACG8343 20,52,53 ; type C: ACG8246 53 ). We conclude that our ABGD-MOTUs 1, 2 and 6 correspond to types A, B and C, respectively, each type comprising many BIN level MOTUs (11, 15 and 10, respectively).…”
Section: Discussionmentioning
confidence: 59%
“…This species has also been emerging as a model for molecular reproduction physiology 50 . Finally, G. fossarum is often used in evolutionary ecology studies such as behavioural ecology 9 , host-parasite relationships 10 , 51 or at the crossroads between parasitology and eco-toxicology 45 , 52 , 53 . Figure 1 Map of Gammarus fossarum sampling sites.…”
Traditional morphological diagnoses of taxonomic status remain widely used while an increasing number of studies show that one morphospecies might hide cryptic diversity, i.e. lineages with unexpectedly high molecular divergence. This hidden diversity can reach even tens of lineages, i.e. hyper cryptic diversity. Even well-studied model-organisms may exhibit overlooked cryptic diversity. Such is the case of the freshwater crustacean amphipod model taxon Gammarus fossarum. It is extensively used in both applied and basic types of research, including biodiversity assessments, ecotoxicology and evolutionary ecology. Based on COI barcodes of 4926 individuals from 498 sampling sites in 19 European countries, the present paper shows (1) hyper cryptic diversity, ranging from 84 to 152 Molecular Operational Taxonomic Units, (2) ancient diversification starting already 26 Mya in the Oligocene, and (3) high level of lineage syntopy. Even if hyper cryptic diversity was already documented in G. fossarum, the present study increases its extent fourfold, providing a first continental-scale insight into its geographical distribution and establishes several diversification hotspots, notably south-eastern and central Europe. The challenges of recording hyper cryptic diversity in the future are also discussed.
“…More recent publications referring to these three types were based on COI, but the sampling remained restricted to or centred around Germany 20,55,56,63 . Our study shows that samples from these studies 20,55,56,63 are associated exclusively with one or two BINs per type (type A: ADH0573 20 ; type B: ACG7784 and ACG8343 20,52,53 ; type C: ACG8246 53 ). We conclude that our ABGD-MOTUs 1, 2 and 6 correspond to types A, B and C, respectively, each type comprising many BIN level MOTUs (11, 15 and 10, respectively).…”
Section: Discussionmentioning
confidence: 59%
“…This species has also been emerging as a model for molecular reproduction physiology 50 . Finally, G. fossarum is often used in evolutionary ecology studies such as behavioural ecology 9 , host-parasite relationships 10 , 51 or at the crossroads between parasitology and eco-toxicology 45 , 52 , 53 . Figure 1 Map of Gammarus fossarum sampling sites.…”
Traditional morphological diagnoses of taxonomic status remain widely used while an increasing number of studies show that one morphospecies might hide cryptic diversity, i.e. lineages with unexpectedly high molecular divergence. This hidden diversity can reach even tens of lineages, i.e. hyper cryptic diversity. Even well-studied model-organisms may exhibit overlooked cryptic diversity. Such is the case of the freshwater crustacean amphipod model taxon Gammarus fossarum. It is extensively used in both applied and basic types of research, including biodiversity assessments, ecotoxicology and evolutionary ecology. Based on COI barcodes of 4926 individuals from 498 sampling sites in 19 European countries, the present paper shows (1) hyper cryptic diversity, ranging from 84 to 152 Molecular Operational Taxonomic Units, (2) ancient diversification starting already 26 Mya in the Oligocene, and (3) high level of lineage syntopy. Even if hyper cryptic diversity was already documented in G. fossarum, the present study increases its extent fourfold, providing a first continental-scale insight into its geographical distribution and establishes several diversification hotspots, notably south-eastern and central Europe. The challenges of recording hyper cryptic diversity in the future are also discussed.
“…Acanthocephalan infections are not expected in aquatic insect larvae, therefore only amphipods were tested for this parasite group. Both P. laevis and Polymorphus minutus were previously found in G. fossarum (van Maren, ; Chen et al ., ) and G. roeselii (Bauer et al ., ), although it is not clear if the Polymorphus sp. in the present study was P. minutus or another species.…”
Summary
Parasite communities of aquatic macroinvertebrates have so far rarely been studied, even if these host organisms are of high relevance for the ecology of freshwater systems and their parasites likely affect the host populations and communities. Therefore, this study addresses this ‘hidden diversity’ in aquatic arthropods of a stream ecosystem in North Rhine‐Westphalia, Germany.
Samples of benthic organisms were taken, and the most abundant host species of major invertebrate groups (amphipods and larvae of chironomids, beetles, caddisflies, mayflies, stoneflies) were tested by PCR for different parasite taxa [microsporidians, acanthocephalans (only amphipods), trematodes, nematodes]. Furthermore, the possible link between prevalence and host feeding type was investigated for each parasite group using a newly developed ‘feeding type score’.
In total, 10 species of aquatic insect larvae and two amphipods of the genus Gammarus spp. were tested and 16 different isolates of microsporidians, three acanthocephalan species, six species of trematodes and one nematode were found. Microsporidians were present in all host species with prevalences ranging from 20 to 100%. Only one presumably specific host–microsporidian association was found for the mayfly Ephemera danica and three isolates were detected exclusively in amphipods. Three acanthocephalan species were detected in the amphipods with prevalences of up to 5.3%. All tested host species were infected with trematodes (prevalences 25–100%), except the caddisfly Sericostoma sp. Nematodes were detected in five host species with prevalences ranging from 14 to 80%. For several positive samples, no sequencing result could be obtained, especially for trematodes and nematodes, therefore, the actual parasite diversity might be even higher.
Active filter feeding showed the highest feeding type prevalence score for microsporidia and nematodes, and passive filter feeders for trematodes, but these results have to be interpreted cautiously as only one active and one passive filter feeder species each were present in the sample.
The impressive number of 26 parasite species (12 microsporidians and 10 helminths) were detected in 12 host species, mostly with surprisingly high prevalences. These results illustrate the ‘hidden diversity’ in aquatic ecosystems and highlight the importance of parasites for aquatic ecological research and the need for studies on the effects of mixed parasite infections on the host populations and communities.
“…However, parasitism is not necessarily a factor increasing the sensitivity and mortality in polluted conditions [56]. Amphipods may benefit from the ability of their parasites (especially acanthocephalans) to accumulate pollutants and so to reduce their concentrations in the tissues of infected hosts as reported by Gismondi et al [178] and Chen et al [179]. Although contrasting results emerge from studies on infected gammarids exposed to pollutants, at the ecosystem level the joint effect of pollution and parasitism could have important implications for contaminant dynamics within food webs and the health of the interacting organisms [26,56].…”
Section: Direct Regulation Of Host Population Sizementioning
Amphipods are a key component of aquatic ecosystems due to their distribution, abundance and ecological role. They also serve as hosts for many micro- and macro-parasites. The importance of parasites and the necessity to include them in ecological studies has been increasingly recognized in the last two decades by ecologists and conservation biologists. Parasites are able to alter survival, growth, feeding, mobility, mating, fecundity and stressors’ response of their amphipod hosts. In addition to their modulating effects on host population size and dynamics, parasites affect community structure and food webs in different ways: by increasing the susceptibility of amphipods to predation, by quantitatively and qualitatively changing the host diet, and by modifying competitive interactions. Human-induced stressors such as climate change, pollution and species introduction that affect host–parasite equilibrium, may enhance or reduce the infection effects on hosts and ecosystems. The present review illustrates the importance of parasites for ecosystem processes using examples from aquatic environments and amphipods as a host group. As seen from the literature, amphipod–parasite systems are likely a key component of ecological processes, but more quantitative data from natural populations and field evidence are necessary to support the results obtained by experimental research.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
