The Ecology of Lough Ine: X. The Hydroid Sertularia Operculata (L.) and its Associated Flora and Fauna: Effects of Transference to Sheltered Water

The hydroid Sertularia operculata is abundant on boulders where the current is strong in the Lough Ine Rapids, especially on the Sill. It decreases in abundance towards positions sheltered from the current (Lilley et al. 1953), and has not been found in Codium Bay which lies just inside the lough. Codium Bay is fully sheltered from the powerful inflow stream; nevertheless there is a slow drift of water across it, always from west to east. The drift is maintained during outflow because water is sucked from all directions into the rapids and during inflow because of the anti-clockwise vortex which then occupies the western half of the South Basin (Bassindale et al. 1956). In this paper we are concerned with the restriction of Sertularia to places exposed to strong current. We have investigated this by observing the fate of living Sertularia on boulders transferred to Codium Bay. During the course of our observations we have also studied the changes in the flora and fauna living on and among the Sertularia, as these organisms might be rather closely implicated.