Sediment cores were collected inside and outside of a bed of a bromophenol-producing marine polychaete, Notomastus lobatus, and examined for impact of the bromophenols on sediment microflora and meiofauna around N. lobatus burrows. No significant differences were found between microbial parameters measured inside and outside of the N. lobatus bed. Integrated 6 cm cores taken adjacent to N. lobatus burrows contained 1.2 x 10' bacteria ml-l. Cell numbers were similar at control sites within the

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... d, but away from burrows, and not significantly different from cell numbers (1.0 X log cells ml-l) at a nearby site. 13H]-acetate net assimilation rates were 12.7 + 5.0 pm01 ml-l h-' adjacent to burrows and 11.9 * 1.4 pm01 ml-' h-' in non-burrow control cores. Microalgal biomass was 20.1 2 1.2 mg chl a m-2 adjacent to burrows and 24.3 + 1.0 mg chl a m-2 in non-burrow control cores. Microalgal production was 4.17 L 0.31 mm01 O2 m-2 h-' near burrows and 5.84 + 0.97 mm01 O 2 m-' h-' in nonburrow controls. Distribution of bacteria, microalgae, and meiofauna showed no consistent effects of proximity to the worm burrows. These data indicate that the concentrations of bromophenols found inside of the N. lobatus worm bed are not inhibitory to sediment microflora and that the microbial populations found there are adapted to exposure to these toxic compounds.