Effects of harbour dredging on soft bottom invertebrate communities: Does environmental variability affect the community responses?

The effect of dredging on the biomass structure of benthic invertebrate communities was examined at 9 sites in the northeastern Baltic Sea during 2002-2007. We analyzed whether and how bottom topography, depth and sediment type contributed to these relationships. In general, the effects of dredging on benthic invertebrates were weak. Dredging clearly increased the biomass of bivalves but the communities recovered in about a year. Bottom topography affected the response of invertebrates to dredging. Flat bottoms were more sensitive to dredging compared to sites situating on slopes. Spatial modelling was proved as a useful tool to predict spatial variability in the effects of dredging on benthic invertebrate communities.