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Gismondi E Rigaud T Beisel JN Cossu-Leguille C 《Environmental pollution (Barking, Essex : 1987)》2012,160(1):17-23
Microsporidia parasites are commonly found in amphipods, where they are often asymptomatic, vertically-transmitted and have several effects on host sexuality and behaviour. As amphipods are often used as models in ecotoxicological studies, we investigated the effect of microsporidian infections on energy reserves and defence capacities of Gammarus roeseli under cadmium stress. Only females were infected by two microsporidia parasites: Dictyocoela roeselum or Dictyocoela muelleri. In physiological conditions, microsporidia had no major effect on energy reserves and defence capacities of G.?roeseli, while under cadmium exposure, energy reserves and antioxidant defence were weaker in infected females. Moreover, higher malondialdehyde levels detected in infected females revealed that they suffered more cellular damages. Our results suggest that microsporidia may affect gammarid fitness in stressful conditions, when parasitic stress cannot be compensated by the host. Consequently, microsporidia parasites should be a factor necessary to take into account in ecotoxicology studies involving amphipods. 相似文献
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Studies of the influence of parasites on host fitness generally conclude that parasites have a strong negative effect on their
hosts. In this study, we have investigated experimentally the role of Polymorphus minutus, an acanthocephalan parasite, on the salinity tolerance of the freshwater amphipod Gammarus roeseli, one of its intermediate hosts. Unexpectedly, P. minutus-infected gammarids were more tolerant to salinity stress than uninfected ones. The mean lethal salt concentrations for 50%
mortality of hosts tested were 17.3 (infected) and 9.7 g/L (uninfected). The parasitic load (one or two parasites per host)
did not affect the result. The size of hosts had no significant influence on the salinity tolerance of either infected or
uninfected gammarids. The mobility of all types of gammarid decreased when the salinity exceeded 9.0 g/L, but there was no
significant difference between infected and uninfected gammarids. We discuss the higher salinity tolerance of infected amphipods
in relation to O2 consumption and osmoregulation. Finally, we demonstrate that the salinity tolerance is enhanced in the parasitized amphipod
but without a significant change in behavior or an osmoregulatory adjustment. 相似文献
3.
Monitoring Changes in Freshwater Macroinvertebrate Communities Along a Salinity Gradient Using Artificial Substrates 总被引:1,自引:0,他引:1
Scientists strive to develop efficient sampling protocols, reducing both the number of samples and processing time required,
which can be adapted for use in a broad range of ecosystems. We investigated the accuracy and usefulness of artificial substrates
in monitoring the impact of rising salinity on freshwater macroinvertebrate communities. We sampled seven sites along a salinity
gradient (from 0.2gL-1 to 2.6gL-1) over a 19-km stretch of the Meurthe River, in northeastern France. All other parameters remained stable in this section
of the river. Artificial substrate samples, each consisting of six liters of pebbles, were removed from the river at one-month
intervals and examined. Results obtained indicated the same qualitative impairments as those found in samples collected using
a Surber net. The use of artificial substrates was found to be a viable alternative method for assessing biological changes
in river quality due to increasing salinity disturbance when Surber sampling cannot be performed. 相似文献
4.
Manipulative parasites are known to alter the spatial distribution of their intermediate hosts in a way that enables trophic
transmission to definitive hosts. However, field data on the ecological implications of such changes are lacking. In particular,
little is known about the spatial coexistence between infected prey and dead-end predators after a parasite-induced habitat
shift. Here, we used an Amphipoda (Gammarus roeseli)–Acanthocephala (Polymorphus minutus) association to investigate how infection with a manipulative parasite affects the predation risk by non-hosts within the
invertebrate community. First, we collected invertebrates by sampling various natural habitats and calculated the distribution
amplitude of amphipods according to their infection status. Infection with P. minutus significantly reduced the habitat breadth in G. roeseli, parasitised individuals being mainly found in floating materials whereas uninfected ones were widespread throughout the
sampled habitats. Second, to test if these changes also affect the risk for P. minutus to be ingested by non-hosts, we estimated the predation risk experienced by G. roeseli within the macro-invertebrate community. The habitat overlap between potential invertebrate predators and G. roeseli showed that the spatial probability of encounter was lower for P. minutus-infected amphipods than for uninfected conspecifics. For the first time, to our knowledge, a study used ecological tools
to bring field evidence for the spatial avoidance of dead-end predators in a manipulated amphipod. 相似文献
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