Abstract
Intertidal communities of Doubtful Sound, New Zealand, were surveyed in 1995 to establish the extent of changes since they were first surveyed 30 years earlier, before the Manapouri power scheme was completed in 1969. This scheme resulted in more than a 3‐fold increase of freshwater inflow to Doubtful Sound, through a tailrace to Deep Cove. Thickness of the low salinity surface layer exceeded the tidal range and was greater at high than low contemporary volumes of tailrace inflow. Intertidal habitats were mostly steep shores of solid rock, little more than 2 m in vertical extent. Freshwater run‐off, groundwater seepage, and aspect to sun were all major factors affecting the intertidal communities. Algae and lichens dominated shore communities. Normally common invertebrates were scarce, especially molluscan grazers. Major changes since the early 1960s included almost total disappearance of Hormosira banksii and exclusion of many other species notably Apophloea lyallii and Elminius modestus to outer reaches of the Sound.