THE IMPORTANCE OF SANDFLAT MORPHOLOGY TO RECRUITMENT OF THE INTERTIDAL SNAIL NASSARIUS-PAUPERATUS DURING 10 CONSECUTIVE YEARS AT 3 SITES INSOUTH-AUSTRALIA

This project was designed to confirm the temporal consistency of inter -site differences in recruitment of an intertidal gastropod, and to te st the hypothesis that these differences are accounted for by differen ces in shore topography. Annual recruitment of the intertidal snail Na ssarius pauperatus (Lamarck) was estimated at two sandflats in Gulf St Vincent, South Australia, over a period of 12 yr (1979 to 1990). At o ne sandflat the gradient was slight, the zone containing N. pauperatus was wide, and there were extensive pools of water at low tide, whilst at the other sandflat the gradient was steeper, the zone containing N . pauperatus was narrower, and there were fewer or no pools. Although recruitment at both sites varied temporally, the density of recruits w as always higher at the first site. These data, together with data cov ering 10 yr (1981-1990) from a sandflat where the gradient of the subs tratum was decreasing due to accretion of sediment, suggest that shore topography is an important determinant of relative recruitment for N. pauperatus in South Australia.