Print PageLocal species assemblages and food webs are usually influenced by abiotic environmental variation and dispersal of organisms among habitat patches that yield meta-community dynamics. In the Oueme River, a lowland river in Benin, Africa, artificial ponds constructed in the floodplain (whedos) provide a supplemental source of fisheries resources, and can provide an excellent model system for examining meta-community dynamics. When the Oueme River breaches its banks during the high-water season, whedos are seeded with a sample, presumably random, of fishes from the river channel. This project documents the shift in species assemblages and food web structure of whedos between the beginning of the dry season, when these first become isolated, and the end of the dry season when they are harvested. Samples of plants, invertebrates, fishes, amphibians and reptiles were collected from 11 whedos plus one natural floodplain depression and one site in the Oueme River channel.
Results/Conclusions
During both periods, assemblage structure was highly consistent among whedos, with domination by predatory fishes with accessory respiratory adaptations for surviving under aquatic hypoxia. Analysis of stable isotope ratios (C, N) of tissue samples revealed major basal production sources assimilated by consumer taxa as well as their trophic positions. Food web structure was highly consistent among whedos, but the structure of whedo food webs was different than those of the natural floodplain habitat and river channel, both of which had more diverse fish assemblages. Relatively low between-season variation was observed in assemblage and food web structure in whedos, and future research should examine meta-community dynamics and food web structure throughout all phases of the annual hydrological cycle.
