abundant on the south end of the west side of the island, but sparse 

 in the central part, which is where the transect was located. This 

 small kelp bed on the southwest wing of the island varied considerably 

 in size during the course of the study. Heavy wave action and grazing 

 by sea urchins may have offset normal seasonal growth. Also, many 

 species, in addition to those listed in Table 1, have distributions 

 that did not coincide with the permanent transects. Some of these 

 were collected during quantitative characterization of major species 

 associations using randomly placed quadrats. Others were found dur- 

 ing reconnaissance dives. 



The analysis of the permanent transect data for significant sea- 

 sonal differences in species densities is summarized in Appendix B, 

 Table B-1. Table 2 provides a summary of the permanent seasonal tran- 

 sect data. The table shows that a total of 37 of the 52 taxa (71 

 percent) examined exhibited significant variability in mean abundance 

 in the transects, apparently due in most cases to seasonal changes in 

 population densities. Twenty of these taxa were absent from the 

 transects during one or more seasons. Seventeen taxa showed signifi- 

 cant seasonal differences despite being present in the transects 

 during all four seasons. Table 2 also indicates the side of the 

 island and season of maximum abundance in the transects for each 

 species. 



Among echinoderms, the urchins (Strongylocentrotus franciscanus 

 and S. purpuratus) and cucumbers (Parastichopus spp.) showed apparent 

 seasonal differences, while none of the four starfish species examined 

 were significantly variable. The results for motile species such as 

 these must be interpreted with caution: seasonal differences may re- 

 flect changes in distribution rather than actual variations in abun- 

 dance. All three ectoproct (moss animal) species examined, which 

 collectively account for the bulk of ectoproct biomass on the island, 

 showed seasonal variability. Gorgonians of genus Muricea varied sea- 

 sonally; Lophogorgia chilensis did not. Among other coelenterates, 

 significant differences were shown by the anemone, Corynactis 

 californica, and the coral, Paracyathus stearnsii, but not by 

 Anthopleura sp. or Astrangia lajollaensis. The two sponges examined 

 showed seasonal differences. Most of the red algae species (Codes 22 

 to 45 in Table 2, and Table B-1) were seasonally variable, as was 

 expected. The only exceptions were Laurencia pacifica, Prionitis 

 lanceolata, and Rhodoglossum affine. Most red algae showed peak den- 

 sities in spring and summer, as was the case with the green algae 

 (Codes 1 to 6 in Table 2, and Table B-1) and generally with the 

 browns (Codes 11 to 20). Conversely, the widely distributed blue- 

 green alga, Phormidium sp. , was most abundant during the winter. 



48 



