Variations in the density and variety of intertidal epilithic microflora

Abstract

-In order to investigate seasonal changes in the density and variety of the microfloral assemblage, samples were collected from an intertidal rock platform near Sydney, Australia, by brushing the rock surface with a toothbrush. A large number of samples was obtained from the natural sandstone substratum at different levels on the shore and at different sites. The assemblage was dominated by a blue-green alga, Anacystis sp., a situation not previously described in any similar system. Also present were diatoms and vanous red, green and brown algal sporelings. Density of cells in the assemblage was greatest in winter, whereas variety was greatest in summer Both density and vanety were greater lower on the shore and at more wave-exposed sites. These patterns differ from those reported by other studies perhaps because the site is different in terms of its weather and its community of grazing gastropods.