Biological Bulletin
Volume 89
Pages 103-121
1945
This paper constitutes an examination of the sedentary communities found on float bottoms and other submerged objects in Newport Harbor, California. Particular attention has been paid to the changes in composition of such communities with time
Field observations on float bottoms and similar structures in Newport Bay disclosed the existence of five or six rather definite communities.
The Mytilus community. Mytilus was without question the most abundant dominant on the float bottoms in Newport Bay during the period of this study. This has not always been the case, according to reliabl observers (G.E. MacGinitie, A.M. Strong, personal communication); during several previous years, Mytilus has not been abundant in the bay. The exact identity of this mussel remains in doubt. It is probably the same form which has bn recorded infrequently from this area as M. edulis. However, conchologists are not entirely agreed that this is the proper designation. It is certainly not M californianus. The Mytilus communities sometimes were observed on a substratum of old and badly decayed bryozoans; at other times were attached directly to the float bottom. Old specimens of Styela or Ciona were often present among the mussel clumps, and various types of sponge were often quite abundant.
The Balanus community. Communities in which Balanus is the dominant organism were not observed on float bottoms in Newport Harbor, although they are frequently observed on experimental surfaces exposed in the open sea at La Jolla. Indeed, Balanus tintinnabulum is probably the principal dominant at La Jolla (Coe, 1932). One experimental panel exposed at this laboratory developed a Balanus community comparable to those observed at La Jolla, however.
The frame was suspended from the laboratory pier, situated in the entrance channel to Newport Harbor about one-half mile from the outer end of the jetties protecting the harbor entrance.
Both Ciona and Styela communities are eventually displaced by Mytilus which at present represents the climax in the float-bottom associations of Newport Harbor.
