Experimental removal of lugworms from marine sand affects small zoobenthos

Abstract

On sandy tidal flats in the North Sea, burrows of Arenicola marina (L.) are a preferred habitat of micro- and meiofauna. Does this also apply to the entire sediment populated by these lugworms compared to experimental sites where A. marina is removed? The comparison reveals that lugworms may account for up to 93% of meiofaunal abundance in the entire subsurface sediment, but there is no difference at the sediment surface. Particularly Turbellaria respond to the neighborhood effects of lugworms, presumably affected by irrigation. However, most of the time during the 3 yr of the experiment, other biotic factors were more important. When tube-building polychaetes and seagrass invaded the site, they also promoted small fauna. Geese caused disturbances. A reversal came when detrimental algal mats caused by sewage covered the entire A. marina-flat, but not the removal site. There is good evidence that promotional effects of macrobenthos on small zoobenthos are a key factor to the latter, but predictability is low and chance plays a major role in the biotic interactions on tidal flats.