intertidal region, and emphasizes only those features unique to this 

 year's study. For a more general description of intertidal community 

 structure, as represented by the undisturbed transects, see NUSCo 1983. 



On a yearly basis at most stations, over half of the available 

 substratum in the high intertidal (Zone I) was unoccupied. Free space 

 generally decreased with increasing exposure. For example, at Millstone 

 Point and Seaside Exposed, a high coverage of ephemeral algae (25-35%) 

 accounted for the low percentage of rock. The high intertidal at Bav 

 Point had less bare rock and more barnacles and ephemeral algae than in 

 any year since 1979, and at Fox Island-Exposed, less than 35% of the 

 substratum was bare. 



The amount of free space is of course inversely related to th^; 

 abundance of intertidal organisms that settle and grow on available 

 surfaces. In Zone I, these organisms are mainly barnacles and ephemeral 

 algae; their abundances vary spatially and temporally. At exposed 

 stations, an algal turf was distinct in spring and autumn, but was 

 reduced in summer and winter due to desiccation and grazing. Coverage 

 by barnacles in Zone I generally increased through spring, following a 

 new set that started in early spring (Feb. - Mar.). Barnacles grew 

 until early summer (May - Jun.); by autumn, coverage decreased as 

 individuals were lost to predation, starvation, or desiccation. 

 Throughout the year, barnacles were more common at the exposed stations 

 than at the sheltered, but all stations showed an increase in barnacle 

 coverage compared to last year. Tn general, the development of the high 

 intertidal community was dependent primarily upon availability of 

 moisture, on a seasonal basis and according to degree of exposure, and 

 secondaiily , upon the abundance and activity of predators and grazers 

 (Connell 196); Grant 1977; NUSCo 1983). 



The mid intertidal (Zone II) had less bare rock than did Zone 1 

 (Table 4a) , although space was available for colonization in this zone 

 at all stations throughout the year. Most of the primary substratum was 

 occupied by barnacles, usually partially covered by a fucoid canopy. 

 Ephemeral algae were seasonally abundant, particularly at the exposed 

 stations . 



The long term cycle of Fucus abundance described previously (NUSCo 

 1983) continued through 1983. Typically, Fucus germlings do not settle 



]A 



