P3.38 Friday, Jan. 6 Is all injury equal? Measuring the effect of repeated injury on sediment disturbance by the polychaete Abarenicola pacifica LINDSAY, S.M.; University of Maine email@example.com
Past research has shown that injury can decrease activity and sediment disturbance by infaunal polychaetes, thereby influencing sediment-mediated competition, adult-larval interactions and recruitment success in marine soft-sediment habitats. However, these studies examined only the effect of single injuries on activity, when repeated injury is more likely the rule. Revisiting a classic study by Woodin (1984), this field experiment examined the effect of single and repeated injury on sediment disturbance by the lugworm Abarenicola pacifica to determine whether repeated injury caused additional reductions in activity. Growth and fecal production by adult worms that had posterior segments ablated once (on day 0), twice (on day 0 and day 14), or not at all (i.e., intact) were monitored for 28 days. By 6 days following injury/handling, >80% of worms in all treatments had defecated at least once. On a daily basis, however, the proportion of worms defecating was lower for worms injured twice compared to those injured once or not at all, and this pattern persisted for two weeks. On average, worms injured once produced less feces compared to intact controls, but only in the first 3 days following injury. In contrast, there was no significant reduction in the mass of feces produced by worms following repeated injury. Relative growth rates of worms in the 14 days following injury/handling were slightly negative for intact worms and worms injured once, but positive for worms injured twice. These results differ from laboratory studies examining the effect of repeated injury on maldanid polychaetes. Factors contributing to this difference and the implications for sediment-mediated interactions will be discussed. Supported by NSF grant OCE0805667 to SML.