Non-overlapping distributions of spionid polychaetes: the relative importance of habitat and competition

The spionid polychaetes, Pygospio elegans Claparède, Pseudopolydora kempi (Southern), and Rhynchospio arenincola Hartman are found in False Bay, Washington. Two species, Pygospio elegans and Pseudopolydora kempi, co-occur in the high intertidal zone. The third species Rhynchospio arenincola occurs only in low intertidal areas. Reciprocal transplant experiments were used to test the importance of intraspecific density, interspecific density, and habitat on the survivorship of experimental animals.