Vertical distribution of benthic macrofauna in sandy sediments of the Pomeranian Bay (southern Baltic) was analysed from a total of 99 samples collected from 10 sites visited four times within 1996-1997. The sediment, collected with a box corer, was divided into 5-cm thick layers. The sediment deeper than 5 cm was found to support about 28% of the total macrofauna biomass; the bulk of the macrobenthic biomass there being due to large individuals of Hediste diversicolor, Marenzelleria viridis, Mya arenaria, and Macoma balthica. The macrofaunal biomass within the depth layer of 5-10 cm is dominated by M. arenaria, polychaetes predominating deeper than 10 cm in the sediment. Most of the sandy bottom macrofauna is accumulated within the top 10 cm of the sediment. The exception is the polychaete Marenzelleria viridis, capable of occurring much deeper. Some individuals of various epifaunal and surficial infaunal species were encountered deep in the sediment; most probably, they found their way there due to burrows dug by large infauna. A relatively accurate estimate of abundance and biomass of the macrobenthos of the sandy bottoms of the Pomeranian Bay can be obtained only when and if the benthos is sampled by a gear that penetrates the sediment down to at least 10 cm.

49-60