EFFECT OF THE AMPHIPOD COROPHIUM-VOLUTATOR ON THE COLONIZATION OF MUD BY THE HALOPHYTE SALICORNIA-EUROPAEA

The upper limit of the distribution of Corophium volutator and the lower limit of the distribution of Salicornia europaea approximately correspond with mean high water of neap tide level (MHWNTL). Previous researchers concluded that the lower limit of S. europaea is determined by the higher frequency and duration of disturbance by tides and waves. At this site, moving water alone is not responsible for the absence of S. europaea below MHWNTL, the activities of C. volutator are important. Below MHWNTL there were fewer seeds, a greater proportion were buried and had failed to germinate than above MHWNTL. Some germinated seeds were present near the surface and the lack of established seedlings was attributed to disturbance by C. volutator. Seedlings transplanted to sediment sprayed with insecticide (to remove the amphipods) had a survivorship similar to those transplanted above MHWNTL, but twice those transplanted to unsprayed sediment. It was concluded that C. volutator prevent establishment of S. europaea partly by burial of seeds, but mostly by preventing establishment by seedlings, and in so doing reduce the stability of the sediment, increase erodability and lessen the prospects for successional development of salt marsh vegetation.