Experimental evidence of ciliate dispersal and successional patterns via endozoochory in temporary aquatic systems

Temporary aquatic ecosystems in Mediterranean regions rely on passive dispersal to maintain connectivity among isolated habitats. In Doñana National Park, Spain, aquatic birds enhance this connectivity by dispersing microbial propagules via endozoochory. We tested whether ciliate dispersal through bird feces facilitates community assembly and ecological succession in disconnected aquatic systems. Bird feces were incubated in aquatic microcosms for 42 days, and 39 ciliate morphospecies emerged. Species richness and abundance increased steadily, peaking between days 21 and 35. Functional succession started with small filter-feeders, followed by predators and mixotrophs. Despite taxonomic changes, ciliate body size remained stable, suggesting dispersal success depended more on cyst resistance than on morphological traits. The emergence of structured, functionally diverse communities confirms that waterbirds not only transport viable propagules but also actively enhance microbial connectivity and drive successional dynamics in temporary wetlands. These results reinforce endozoochory as a key mechanism shaping microbial metacommunities and supporting biodiversity in fragmented aquatic landscapes. Given that species were identified in vivo observation without molecular or staining confirmation, our results should be interpreted as community-level patterns rather than precise species-specific dynamics.