Sediment processing in Capitella spp. (Polychaeta : Capitellidae): strain-specific differences and effects of the organic toxicant fluoranthene

The effects of the widespread polycyclic aromatic hydrocarbon (PAH) fluoran thene on sediment-processing rates in the infaunal polychaete Capitella spp . were investigated by comparing five populations of this deposit-feeding s pecies complex: Capitella sp. I from New York, USA; Capitella sp. M from Mi les, Greece; Capitella sp. S from Sylt, Germany; and two unidentified Capit ella populations from salmon farm sediments - Capitella population K from K ilmelford, Scotland and Capitella population C from Cranford, Ireland. Repl icate worms from each strain were exposed to 0, 10, and 95 mug (g dry wt se diment)(-1) fluoranthene (= mug/g fluoranthene) for a period of 16 days. In itial and final wet and dry weights (mg) of worms and worm-specific growth rates (WSGRs) were calculated. Sediment processing was measured as the sum of the total dry weight of pellets produced during the experiment, and we e stimated size-specific processing rates (SSPRs) as a measure of sediment pr ocessed per mg worm dry weight per day. The five populations of Capitella s pp. differed significantly in body size, WSGR, and sediment-processing rate s. Capitella sp. I grew faster than all of the other populations. Capitella population C and Capitella population K from fish farm sediments, with the largest body lengths (up to 52.0 +/- 27.2 mm), had the highest processing rates, whereas the small Capitella sp. S (up to 17.1 +/- 5.6 mm) had the lo west. There were also significant differences in SSPR among populations wit h Capitella sp. I having a higher SSPR (about 12 x body wt/day) than Capite lla population C (about 5 x body wt/day) and Capitella population K (3 x bo dy wt/day). The fluoranthene concentrations used in the present study, whil e representing moderately to highly contaminated conditions, had only margi nal effects on sediment-processing and growth rates of all of the Capitella populations examined. Processing of contaminated sediment by Capitella spp . may be important in the remediation of PAH-contaminated sediment.