Data from: Alternative food sources interfere with removal of a fungal amphibian pathogen by zooplankton

1. While the amphibian disease chytridiomycosis is causing ongoing
population declines and biodiversity losses around the globe, efficient
mitigation strategies are lacking. The free-living zoospores of the
causative agents of this disease, the chytrid
pathogens Batrachochytrium dendrobatidis (Bd)
and Batrachochytrium salamandrivorans (Bsal), are a
potential food source for filter-feeding micropredators as part of the
aquatic food web. While consumption of zoospores can lower environmental
pathogen loads, alternative food sources may interfere with pathogen
removal rates. 2. We compared the ability of three filter-feeding
zooplankton species, i.e. the cladoceran Daphnia magna, the
rotifer Brachionus calyciflorus and the
ostracod Heterocypris incongruens, to remove Bd
zoospores in water and investigated the effect of alternative food
sources, i.e. the green algae Pseudokirchneriella
subcapitata and Chlorella vulgaris, on zoospore
ingestion by D. magna. 3. D. magna was the only
micropredator candidate that effectively removed Bd zoospores from its
environment, with an average removal rate of 1,012 ± 542 GE
ind.-1 h-1 within our test system. High concentrations
(1x105 cells/mL) of large and easily ingestible P.
subcapitata reduced pathogen removal rates, whereas the small and
less edible C. vulgaris did not interfere with pathogen
removal. 4. Synthesis and applications: We showed
that Daphnia spp., which are keystone species in all sorts of
aquatic habitats worldwide, are promising target agents for biologically
mitigating chytridiomycosis infections and how natural food sources may
interfere with this strategy. We also suggest potential management actions
for biological disease mitigation, aiming to optimize environmental
conditions for these target filter-feeders, thereby reducing pathogen
densities and eventually infection pressure in amphibian hosts. Examples
of such management actions include, but are not limited to, removal of
planktivorous fish, habitat restoration, nutrient control or agrochemical
regulation in the vicinity of amphibian breeding ponds. Further studies,
including field trials, are needed to confirm the effects of pathogen
consumption on infection dynamics in natural situations and investigate
the impact of intervention actions.