Differences between the species composition and total resources of bottom macrofauna in two areas of Puck Bay were analysed in 1962-63 and 1984-85. These areas were the shallow Puck Lagoon, originally overgrown by luxuriant multi-specific submerged meadows which later un-derwent serious degradation, and the outer Puck Bay with its very limited extent of underwater meadows. In the first area the total resources were found to have decreased, whereas in the second the bottom macrofauna had increased. Both regions saw a four-fold increase in polychaete bio-mass, that of Hediste diversicolor in particular. In the outer Puck Bay the mollusc biomass in-creased, especially that of Mytilus trossulus, Macoma balthica, and the crustacean Gammarus sp., Balanus improvisus, and especially Corophium volutator. The biomass of most taxonomic groups decreased, which in the Puck Lagoon is evidence for the degradation of the bottom macroflora.