Meeting Abstract
In the northeast Pacific, the giant frilled anemone Metridium farcimen forms dense aggregations on subtidal ledge and boulder communities and underneath floating docks in marinas. M. farcimen is a competitive dominant, excluding many of the other invertebrates that occupy primary space on walls and ledges, but details on its distribution and how the population is controlled are poorly understood. The distribution of M. farcimen was studied through extensive surveys at twelve locations in the San Juan Island archipelago. Current, light, and temperature at these sites was compared with the density of M. farcimen. Anemones were distributed along vertical walls in shallow communities (less than 18 meters), but become more abundant on sloping and horizontal surfaces deeper. M. farcimen populations are highly impacted by both light and current, but not temperature, preferring light levels insufficient to grow kelp and other tall macroalgae and current high enough to reduce sedimentation and deliver sufficient food. Abiotic and biotic factors help control this species from becoming an omnipresent competitive dominant.
