Predatory effects of Nephtys hombergii on other polychaetes in tidal flat sediments

Abstract

tidal flats near the island of Sylt in the North Sea the endobenthic polychaete Nephtys hombergii (Savigny 1818) was added to enclosures. This caused a significant decline in other polychaetes, notably the deposit-feeders Scoloplos armiger (0. F. Miiller) and Heteromastus filiform~s (Claparede). These 2 were also the main prey components inside the guts of N. hombergii. Occasionally, other predatory polychaetes were eaten and the amount of nematodes ingested increased with decreasing size of N. hombergii. Total prey consumption is estimated to be above 1 g C m-2 yr-' or at least one tenth of the consumption of all epibenthic predators together. Cages protecting N. hombergii from flsh and birds caused its abundance to be elevated. The experiments suggest that N. hornbergii is an important intermediate predator in the Wadden Sea.