A contribution to the ecology of Actinocyclus roperi onHarbour Beach, St. Ives, Cornwall

摘要

Diatoms were first noticed in the winter of 2003/4 in ripple pools in the harbour. The sand surface was sampled and found to consist overwhelmingly of the one species. Sand cores taken from above the ripple pools showed large numbers on the surface, and to a depth of several centimetres. Retention of cells against flowing water and adhesion to sand grains was observed. Scanning electron micrographs demonstrated rimoportulae around the valve mantle which may have a role to play in adhesion. Auxospore formation was observed in which the major cell diameter increased by about one hundred percent. Predation by bottom feeding fish and micro predation by cilliates and ostracods was observed. It is suggested that Actinocyclus roperi (de Brebisson) Grunow be considered a transient member of the epipsammic microflora of sheltered shores.