Fish as potential dispersal agents for floodplain plants: first evidence in North America

In river-floodplain ecosystems with seasonal flood pulses, many species display adaptations to take advantage of resources in the aquatic-terrestrial transition zone. Frugivory and seed dispersal by fishes is a clear example of such adaptations, known primarily from South American river-floodplain systems. Here, we document consumption of red mulberry (Morus rubra) and swamp privet (Forestiera acuminata) fruit by channel catfish (Ictalurus punctatus) in the floodplain of the Mississippi River, U.S.A., and demonstrate that red mulberry and swamp privet seeds will germinate after being consumed by channel catfish. In a common-garden experiment, consumption of fruits and seeds by channel catfish improved germination success of these riparian plants relative to a treatment simulating fruit dropped during a flood without being consumed by fish. This is the first study to provide evidence of frugivory and viability of seeds ingested by fish in a North American river-floodplain ecosystem. Frugivory and seed dispersal by fishes may be more widespread than previously thought.