Moderate predation on meiofauna by the macrobenthos of the Wadden Sea

The role of meiofauna in the trophic web of marine ecosystems is a controversial topic. During an experimental study on tidal flats in the eastern part of the North Sea, potential predators on meiofauna were kept in enclosures. A gobiid fish, shrimp, crabs, an amphipod, four polychaete worms and a nemertine were tested for their ability to decimate nematodes, turbellarians, ostracods and benthic copepods. Only few macrobenthic species preyed heavily on permanent meiofauna: juveniles of the shore crabCarcinus maenas, the hermit crabPagurus bernhardus with the colonial hydrozoanHydractinia echinata on its shells, and the rag wormNereis diversicolor. When benthic infauna was protected from these predators with exclosures, juvenile macrofauna responded with a marked increase in number, while the permanent meiofauna remained unaltered except for a limited increase in nematodes. It is concluded that in the Wadden Sea abundance of permanent meiofauna (Nematoda, Turbellaria, Ostracoda, Copepoda) is only locally or temporarily regulated by macrobenthic predators.I acknowledge a grant from the Deutsche Forschungsgemeinschaft (DFG).