(e.g., grazing and predation) , degree of exposure, intertidal height, 

 and season. To clarify some of these relationships, the monitoring 

 program includes manipulative experiments that try to isolate individual 

 factors. 



Recolonization Transects 



Monitoring experiments to determine rates and patterns of 

 recolonization of intertidal communities that were begun in 1979 have 

 continued through 1983. The trnnsects were reburned in September 1981, 

 and represent an autumn denuding; the sampling design was the same as 

 for the spring denuding (begun in April 1979 and described in NUSCo 

 1982) . Average percent cover by each functional group over the latest 

 experiment (Sep. 1981 - Sep. 1983) is given in Table 4b; monthly values 

 for each species found in the recolonization transects are presented in 

 Appendix II. In the following discussion "exposed stations" are 

 represented by FE and WP; FS and GN are "sheltered stations". 



Recovery towards pre-experimental conditions progressed beyond that 

 previously reported (NUSCo 1983). Recolonization in the high intertidal 

 (Zone I) was much faster at the exposed stations; this was attributed to 

 wave action, which increased available moisture, and decreased the 

 abundance and activity of grazers (Table Ab) . 



Recolonization in mid and low intertidal zones was seen most 

 clearly in the rate of recovery of Balanus and Fucus populations. As 

 reported in the past (NUSCo 1981), when substrata were denuded in 

 spring, barnacles and Fucus colonized very quickly; particularly at the 

 exposed stations, populations reach pre-experimental levels in as little 

 as 8 months. When substrata were denuded in autumn, ephemeral algae 

 settled almost immediately at the exposed stations; barnacles and Fucu s 

 did not appear at any station as more than a trace until the following 

 spring and summer. Once settled, however, Fucus cover increased quickly 

 at the exposed stations (faster in Zone III than in Zone II) . By 

 September 1982, Fucus cover in the low intertidal of Fox Island-Exposed 

 was ca. 25%, and almost 50% at White Point. Fucus recovery at the 

 sheltered stations was slower, and in September 1982, averaged only 5% 

 at Giants Neck and Fox Island-Sheltered. As at the exposed stations. 



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