One of the greatest unresolved mysteries since the 19th century is to observe wide distributions of relatively immobile species throughout aquatic ecosystems. How do aquatic plants and small invertebrates disperse across kilometers of ocean or dry land? In this talk I will present my past and current research on the possibility that more mobile animals, especially waterbirds, transport plant seeds and aquatic invertebrates in their digestive system or adhering to their outside. I will talk about laboratory experiments, fieldwork and population genetic analyses.