The Distribution of the Fauna of Some Intertidal Sands and Muds on the Northumberland Coast

Abstract

Quantitative data on abundance of each species was obtained with use of a metal frame enclosing 1/4 sq. m. pH, salinity, depth of water table, and consistency of the sand were measured. The fauna of the intertidal zone can withstand a considerable range of environmental conditions, but some, e.g., Nerine cirratulus, Phyllodoce maculata, Nereis diversicolor, and especially Haustorius arenarius, are favored by prolonged exposure between tides; some, such as Nerine cirratulus, and again especially H. arenarius, thrive best in clean sand. Most spp. are most numerous in muds of fairly high organic content, if the consistency is not too fine. The period of exposure, the degree of desiccation, the % of silt and the organic content of the sand are apparently the main factors which determine the changes in the dominant spp. of the communities. The variations of pH and salinity recorded had little or no obvious correlation with the distribution of the fauna. The zoning of the fauna is chiefly due to the period of exposure between tides and to competition for food between the various spp. Correlation is made between size and age in Macoma balthica and Cardium edule.