Waterbirds and other drivers of endoparasite communities across a
hierarchy of spatial scales
Abstract
Our understanding of the drivers of parasite community structure is
compromised by poor sampling and historical focus on one host-one
parasite systems. Yet parasites are ubiquitous and co-infections are
common. This study aimed to identify how a range of drivers
(connectivity, region, host-parasite interactions, parasite-parasite
interactions) contribute to structuring endoparasite metacommunities.
Within-host to landscape level patterns of malacosporean myxozoans
infecting dormant propagules (statoblasts) of the freshwater bryozoan,
Cristatella mucedo, were characterised. Large-scale databases were used
to develop a metric for waterbird connectivity based on species
turnover. Overall infection prevalence, assessed by PCR, was associated
with high waterbird turnover at the site level, providing evidence that
waterbirds act as parasite dispersal vectors. RFLP analysis revealed
eight malacosporean infection profiles. Traits of both hosts (e.g.
habitat preferences) and parasites (e.g. transmission success) were
linked with impacts of hydrological connectivity. Flooding regimes,
nutrient enrichment from agriculture landscapes, and waterbird abundance
were linked with regional impacts. Co-infections within tiny statoblasts
(up to four) were common. Uninfected statoblasts were larger and there
was no detectable difference in sizes of statoblasts with single vs.
multiple infections. Co-occurrence analysis identified positive
associations between four malacosporean taxa. The lack of negative
associations suggests no competition amongst malacosporeans infecting
statoblasts. There was no evidence that host-parasite interactions
result in local adaptation of parasites to host clones. Hydrologically
isolated sites had greater malacosporean diversity and enhanced levels
of overall infection prevalence and co-infection, suggesting that such
sites are malacosporean hotspots. Our study provides novel insights on
the complex factors that can structure parasite communities in
freshwater invertebrate hosts across the UK.