Temporal stability of polymorphic Arctic charr parasite communities reflect sustained divergent trophic niches

Polymorphic Arctic charr Salvelinus alpinus populations frequently display
distinct differences in habitat use, diet and parasite communities.
Changes to the relative species densities and composition of the wider
fish community have the potential to alter the habitat-niche of sympatric
Arctic charr populations. This study evaluated the temporal stability of
the parasite community, diet and stable isotopes (δ13C, δ15N) of three
sympatric Arctic charr morphs (piscivore, benthivore and planktivore) from
Loch Rannoch, Scotland, in relation to changes to the fish community. All
Arctic charr morphs displayed distinct differences parasite communities,
diet and stable isotope signatures over time, despite the establishment of
four new trophically transmitted parasite taxa, and increased fish and
zooplankton consumption by the piscivorous and planktivore morphs
respectively. Native parasite prevalence also increased in all Arctic
charr morphs. Overall, Loch Rannoch polymorphic Arctic charr morph
populations have maintained their distinct trophic niches and parasite
communities through time despite changes in the fish community. This
result indicates that restocking of a native fish species has the
potential to induce shifts in the parasite community and diet of Arctic
charr morphs.