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Microhabitat distributions and species interactions of ectoparasites on the gills of cichlid fish in Lake Victoria, Tanzania
Full text linkHeterogeneous exposure to parasites may contribute to host species differentiation. Hosts often harbour multiple parasite species which may interact and thus modify each other's effects on host fitness. Antagonistic or synergistic interactions between parasites may be detectable as niche segregation within hosts. Consequently, the within-host distribution of different parasite taxa may constitute an important axis of infection variation among host populations and species. We investigated the microhabitat distributions and species interactions of gill parasites (four genera) infecting 14 sympatric cichlid species in Lake Victoria, Tanzania. We found that the two most abundant ectoparasite genera (the monogenean Cichlidogyrus spp. and the copepod Lamproglena monodi) were non-randomly distributed across the host gills and their spatial distribution differed between host species. This may indicate microhabitat selection by the parasites and cryptic differences in the host-parasite interaction among host species. Relationships among ectoparasite genera were synergistic: the abundances of Cichlidogyrus spp. and the copepods L. monodi and Ergasilus lamellifer tended to be positively correlated. In contrast, relationships among morphospecies of Cichlidogyrus were antagonistic: the abundances of morphospecies were negatively correlated. Together with niche overlap, this suggests competition among morphospecies of Cichlidogyrus. We also assessed the reproductive activity of the copepod species (the proportion of individuals carrying egg clutches), as it may be affected by the presence of other parasites and provide another indicator of the species specificity of the host-parasite relationship. Copepod reproductive activity did not differ between host species and was not associated with the presence or abundance of other parasites, suggesting that these are generalist parasites, thriving in all cichlid species examined from Lake Victoria.sponsorship: This research was funded by the Swiss National Science Foundation and the University of Groningen, the Netherlands (Ubbo Emmius Programme). Infrastructure was provided by the Natural History Museum in Lugano, Switzerland and Hasselt University, Belgium (EMBRC Belgium -FWO project GOH3817N). We acknowledge Antoine Pariselle for help with identification of parasites belonging to Cichlidogyrus. (Swiss National Science Foundation, University of Groningen, the Netherlands (Ubbo Emmius Programme), Natural History Museum in Lugano, Switzerland, Hasselt University, Belgium (EMBRC Belgium - FWO project)|GOH3817N)status: Published onlin
Parasites through time. Museum collections as a tool for parasite conservation and ecosystem health monitoring.
No full textChanges in parasite community structure may elucidate causes for ecosystem decline in Lake Victoria
No full textHuman-induced environmental changes may influence the host-parasite interactions and may lead parasites to expand their host range (i.e. spillover to novel host species). Lake Victoria, the youngest of the African Great Lakes, is a biodiversity hotspot that experienced drastic anthropogenic changes since the 1950s: multiple invasions (e.g. Nile perch), eutrophication, overfishing. Such ecosystem perturbations occurred simultaneously and led to a rapid decline of biodiversity (halving haplochromine species in few decades) and to an overall reduction in complexity, with consequences also on human health (e.g. emerging infectious diseases).
Although parasites contribute to maintain ecosystem health, it is often overlooked how parasite community structure changes in response to ecosystem changes. We expect that low host specificity and host switches are favoured in disturbed ecosystems (we already found indications for this pattern in cichlid fish of Lake Victoria). We aim to understand if recent changes in host specificity of monogenean parasites in Lake Victoria resulted from a natural state of the lake or if it has been recently induced by human disturbances. We use historical collections to detect recent changes in the structure of fish parasites in Lake Victoria. To disentangle which perturbation (eutrophication, Nile perchpredator invasion) mainly caused such changes, we use a space-for-time approach in which we model parasite shifts across lakes that share parasite species as well as closely related cichlids but that differ in disturbance.
Since perturbations that have occurred in Lake Victoria are also occurring in other ecosystems, we can use the changes in host ranges of parasites as sentinel, to better monitor and hence conserve ecosystem health elsewhere.Swiss National Science Foundation (SNSF
Temporal changes in the flatworm parasite communities of Lake Victoria cichlid fishes in response to ecosystem changes
No full textSpecies interactions are particularly crucial for ecosystem health and for conservation in face of global change. Human-induced environmental changes may influence the host-parasite interactions and may lead parasites to expand their host range (i.e. spillover to novel host species). Although parasites contribute to maintain ecosystem health, it is often overlooked how parasite community structure changes in response to ecosystem changes. We investigate this in flatworms parasitizing cichlid fish in Lake Victoria.
Lake Victoria, the youngest of the African Great Lakes, is a biodiversity hotspot that experienced simultaneous drastic anthropogenic changes: multiple invasions (e.g. Nile perch), eutrophication and overfishing. We use recent and historical fish collections to assess whether the communities of parasitic flatworms changed after such ecosystem perturbations in Lake Victoria. We analysed flatworm parasite infection in 12 cichlid fish species, representing 7 eco-morphological groups, sampled between 1973 and 2014. We identified 6 species of monogeneans (1 Gyrodactylus and 6 Cichlidogyrus, which 4 are new to science) and 2 species of copepods.
An overall decrease in parasitic flatworm diversity was not observed. Instead, some flatworm parasite species are declining, while others are increasing in abundance, indicating that parasite species respond differently to ecosystem disturbances. Moreover, some flatworm species are becoming more generalists, infecting hosts species that they did not infect before ecosystem changes in Lake Victoria. This may suggest that ecosystem disturbances favor host switching.
Since changes that have occurred in Lake Victoria are also occurring in other ecosystems, we can use flatworm parasites as sentinel for ecosystem health, which might contribute to better strategies for linking conservation and ecosystem health.Swiss National Science Foundation (SNSF
Temporal changes in the flatworm parasite communities of Lake Victoria cichlid fishes in response to ecosystem changes
No full textSpecies interactions are particularly crucial for ecosystem health and for conservation in face of global change. Human-induced environmental changes may influence the host-parasite interactions and may lead parasites to expand their host range (i.e. spillover to novel host species). Although parasites contribute to maintain ecosystem health, it is often overlooked how parasite community structure changes in response to ecosystem changes. We investigate this in flatworms parasitizing cichlid fish in Lake Victoria.
Lake Victoria, the youngest of the African Great Lakes, is a biodiversity hotspot that experienced simultaneous drastic anthropogenic changes: multiple invasions (e.g. Nile perch), eutrophication and overfishing. We use recent and historical fish collections to assess whether the communities of parasitic flatworms changed after such ecosystem perturbations in Lake Victoria. We analysed flatworm parasite infection in 12 cichlid fish species, representing 7 eco-morphological groups, sampled between 1973 and 2014. We identified 6 species of monogeneans (1 Gyrodactylus and 6 Cichlidogyrus, which 4 are new to science) and 2 species of copepods.
An overall decrease in parasitic flatworm diversity was not observed. Instead, some flatworm parasite species are declining, while others are increasing in abundance, indicating that parasite species respond differently to ecosystem disturbances. Moreover, some flatworm species are becoming more generalists, infecting hosts species that they did not infect before ecosystem changes in Lake Victoria. This may suggest that ecosystem disturbances favor host switching.
Since changes that have occurred in Lake Victoria are also occurring in other ecosystems, we can use flatworm parasites as sentinel for ecosystem health, which might contribute to better strategies for linking conservation and ecosystem health.Swiss National Science Foundation (SNSF
How flatworm parasite communities changed in response to human-induced ecosystem perturbations in Lake Victoria
No full textGlobal change is causing distribution shifts and population declines of countless plants and free-living animals. How parasites are affected by global change is largely unknown, despite their ubiquity and importance for ecosystem functioning (e.g. regulation of host populations, increase of food web connectivity). Human-induced environmental changes are expected to alter parasite abundance and host-parasite interactions (e.g. spillover to novel host species), but the direction of such changes is unclear.
Lake Victoria, the youngest of the African Great Lakes, is a biodiversity hotspot that experienced simultaneous drastic anthropogenic changes: multiple invasions (e.g. Nile perch), eutrophication and overfishing. We use historical fish collections – harboring a hidden parasite collection – to test whether parasite abundance and host range changed in response to anthropogenic changes in Lake Victoria. We analysed ectoparasite infection in 13 cichlid fish species, representing 7 eco-morphological groups, sampled between 1973 and 2014.
Overall parasite abundance, but not parasite diversity, declined after impacts on Lake Victoria. Most ectoparasite species are declining, while few others are increasing in abundance, indicating that parasite species respond differently to ecosystem disturbances. The host range of most ectoparasitic flatworms changed, as they disappeared from some host species and colonized few new host species that they did not infect before ecosystem changes in Lake Victoria. This may suggest that ecosystem disturbances favor host switching.
Since changes that have occurred in Lake Victoria are also occurring in other ecosystems, our results suggest that we can use flatworm parasites as sentinel for ecosystem health, which might contribute to better strategies for linking conservation and ecosystem health.Swiss National Science Foundation (SNSF
Parasites through time. Museum collections as a tool for parasite conservation and ecosystem health monitoring.
No full textHow flatworm parasite communities changed in response to human-induced ecosystem perturbations in Lake Victoria
No full textGlobal change is causing distribution shifts and population declines of countless plants and free-living animals. How parasites are affected by global change is largely unknown, despite their ubiquity and importance for ecosystem functioning (e.g. regulation of host populations, increase of food web connectivity). Human-induced environmental changes are expected to alter parasite abundance and host-parasite interactions (e.g. spillover to novel host species), but the direction of such changes is unclear.
Lake Victoria, the youngest of the African Great Lakes, is a biodiversity hotspot that experienced simultaneous drastic anthropogenic changes: multiple invasions (e.g. Nile perch), eutrophication and overfishing. We use historical fish collections – harboring a hidden parasite collection – to test whether parasite abundance and host range changed in response to anthropogenic changes in Lake Victoria. We analysed ectoparasite infection in 13 cichlid fish species, representing 7 eco-morphological groups, sampled between 1973 and 2014.
Overall parasite abundance, but not parasite diversity, declined after impacts on Lake Victoria. Most ectoparasite species are declining, while few others are increasing in abundance, indicating that parasite species respond differently to ecosystem disturbances. The host range of most ectoparasitic flatworms changed, as they disappeared from some host species and colonized few new host species that they did not infect before ecosystem changes in Lake Victoria. This may suggest that ecosystem disturbances favor host switching.
Since changes that have occurred in Lake Victoria are also occurring in other ecosystems, our results suggest that we can use flatworm parasites as sentinel for ecosystem health, which might contribute to better strategies for linking conservation and ecosystem health.Swiss National Science Foundation (SNSF
Parasites warning us on ecosystem changes. The case study of fish parasites in anthropogenically impacted Lake Victoria
No full textHow parasites are affected by global change is largely unknown, despite their ubiquity and crucial role for ecosystem
health in maintaining complexity and contributing to ecosystem robustness. Human-induced environmental changes
are expected to alter parasite abundance and host-parasite interactions (e.g. spillovers), but the direction of such
changes is unclear, as its consequences for ecosystem health. Lake Victoria, the youngest of the African Great Lakes,
is a biodiversity hotspot that experienced simultaneous drastic anthropogenic changes, the main being: Nile perch
invasions and eutrophication. We compared gill macroparasite communities of 13 cichlid fish species 20 years before
and after the onset of these anthropogenic perturbations, using historical and recent fish collections. We observed a
decline in parasite abundance, biodiversity indices, and co-infections. The host-parasite network rearranged, some
parasites disappeared from some host species and colonized few new ones, in a way that reduces ecosystem stability.
This highlights the need to preserve parasites and their ecosystem services in face of global change. We also
disentangled the cause of such changes, by comparing parasite communities between lake ecosystems similar and close
to Lake Victoria but differing in perturbation types. This space-for-time approach revealed that the observed changes
in parasite communities in Lake Victoria are not due to natural fluctuations, but rather result from the effect of both
studied perturbations. Since changes that have occurred in Lake Victoria are also occurring in other ecosystems, we
can use parasites as sentinel for ecosystem health, which might contribute to better strategies for linking conservation
and ecosystem health
Monitoring wildlife parasites for One Health
No full textUnderstanding how ecosystems respond to stressors like climate change and human activities is key for One Health initiatives. Parasites play a critical role in maintaining ecosystem complexity, by increasing biodiversity (which can dilute the impact of parasites on individual hosts) and the number of interspecific interactions, and ultimately ecosystem robustness and resilience in face of global change. Anthropogenic changes may alter ecosystem health, potentially inducing shifts in host ranges (e.g. spillovers). Such human-induced shifts in host ranges need to be closely monitored and their mechanisms beter understood, as they could result in the emergence of new infectious diseases.
We investigated the link between habitat degradation and shifts in parasite communities, using parasites as indicators of ecosystem health in Lake Victoria (Eastern Africa). We compared macroparasite communities of 13 cichlid fish species 20 years before and after the onset of anthropogenic perturbations, using historical and recent fish collections. We observed a decline in parasite abundance, biodiversity indices, co-infections and a change in host-parasite combinations, with switches to new host species. This highlights the need of a monitoring plan of wildlife parasites, to preserve their ecosystem services in face of global change.
We also assessed the effect of two recent human disturbances – predator invasion and eutrophication – on parasite communities, by comparing parasite communities between lake ecosystems similar and close to Lake Victoria but differing in perturbation types. This space-for-time approach will reveal whether the observed changes in parasite communities in Lake Victoria reflect a natural state or are a result of recent human disturbances and, if so, which disturbance.
The study confirms the interconnection between wildlife, ecosystem and humans, and shows the potential of the new “historical ecology of parasitism” sub-field in the context of One Health research, offering the opportunity for long-term monitoring of wildlife diseases. This could reveal early warning signs of infection outbreaks or emergence of new diseases and contribute to develop policy strategies.International Coordination Action G0ADU24N of the Research Foundation-Flanders (FWO-Vlaanderen)
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