QUANTIFYING SEDIMENT DISTURBANCE BY BROWSED SPIONID POLYCHAETES - IMPLICATIONS FOR COMPETITIVE AND ADULT-LARVAL INTERACTIONS

Sediment-dwelling animals (infauna) in marine soft-bottom habitats oft en lose body parts exposed above the sediment surface to browsing pred ators. Such tissue loss can cause reduced activity, feeding, growth, a nd reproduction. Browsing (or sublethal) predation may also influence competitive interactions via changes in sediment disturbance activity. Increased browsing rates should result in decreased sediment disturba nce. We quantified the area of sediment disturbed by groups of spionid polychaetes subject to different regimes of feeding palp loss. For Ps eudopolydora kempi (Southern), cores with higher numbers of regenerati ng worms had less area of surface sediment disturbed (reductions range d from 30% to nearly 100%), and this effect persisted for at least 1 w k. Fecal production was similarly reduced. Fecal production by another spionid, Rhynchospio glutaeus (Ehlers), was reduced only when all wor ms in a core were regenerating both feeding palps. Tube-building was n ot affected in either species. By quantifying the zone of influence of browsed infauna, we can make better predictions of the level of brows ing necessary to reduce competitive and adult-larval interactions.