PREFACE

Organisms living in sandy shore of seas, lakes and rivers create community called psammon. Sandy microhabitats like fresh-water beaches are the peculiar and extremely dynamic sites. Large daily temperature fluc-tuations of sand, i.e. excessing 20°C, strong wave action damaging the structure of sand grains, small living space, low oxygen con-centrations and high concentrations of in-organic nutrients and organic compounds seem to be rather unfavourable conditions for life (Wiszniewski 1932, 1934). Never-theless, sandy beaches are inhabited by differ-ent groups of organisms, such as bacteria, al-gae, protists, rotifers, copepods, tardigrades, nematodes, gastrotrichs, turbellarians an