Molluscan biocoenoses and thanatocoenoses in the Ria de Arosa, Galicia, Spain

CONTENTS Introduction...................... 4 I Description of the area............ 5 Topography................................................ 5 Climate........................5 Hydrography: Tides and currents................... 9 Temperature and salinity......... 11 Oxygen........... 12 Turbidity........... 14 Sediments : Grain-size........... 14 Organic carbon content........ 16 Summary.............. 19 II Methods.............. 19 Discussion of methods........... 20 Mollusc-assemblages............ 25 III The Rio Ulla and Umia.......... 25 Fauna and environment..... ..... 25 Important species............ 31 Comparison with other areas.......... 32 Transport.............. 32 IV The marginal zone............ 32 The environment............. 32 The marginal fauna............ 33 Important species............ 34 Other skeletal remains........... 42