Evidence that long-distance dispersal of aquatic invertebrates by ducks increases with propagule size

Migratory ducks are key dispersal agents for aquatic organisms, yet differences in their potential for short- and long-distance dispersal are still poorly understood, particularly differences among aquatic invertebrate taxa.

Using seven species of aquatic invertebrates and a duck species known to feed on them in the wild (the northern shoveler) as a model system, we evaluated whether their potential for endozoochorous dispersal varies among 5 of the species and scales with propagule size for the 7 species. We also tested the expectation of a lower dispersal potential for invertebrate propagules, as compared to plant seeds; and evaluated whether intra-specific variation (in particular, sexual dimorphism) influences the potential of waterbirds as dispersal vectors.

An experiment with 5 invertebrate species demonstrated that most resting eggs (68–95%) were retrieved by 4 h after ingestion, with maximum gut passage times ranging from 16 h for Daphnia magna to 36 h for Artemia salina ..., Data include the retrieval and hatching rates of the resting eggs of five zooplankton species fed to captive shoveler ducks and the output (dispersal curves) of models that combine migratory duck movements with gut passage times. ,