(1). Total Biota Cover and Number of Taxa 
Estimates of total biota cover at the different levels of 
north jetty stations indicated no consistent or marked differences 
between inner and outer sites on the same side of the jetty (Appendix 
E.1). Biota cover on the rocks one year after construction was generally 
as great as in subsequent years (Fig. 2). This was primarily due to 
early settling of blue-green algae and the barnacle Chthamalus fragilis 
intertidally, and settling of the mussel Brachidontes exustus at lower 
intertidal and subtidal levels. 
Biota cover at inner and outer south jetty stations did differ 
considerably in the spring of 1980, with outer sites having less cover 
than inner sites at all levels where biota was present (Appendix E.2). 
Rocks at the outer stations had only been submerged for 2-3 months as 
compared to 7 months of submersion at the inner stations. By the summer 
of 1980, biota cover at all levels on the rocks had increased to percen- 
tages as great or greater than those found in subsequent sampling 
periods (Fig. 3). 
In the upper intertidal zone (1.5 m - 2.0 m above MLW), biota cover 
was often greater on the wave-exposed side as compared with the 
sheltered side of the jetties (Figs. 2 and 3). This vertical extension 
in the amount of biota cover on the exposed side is a common pattern 
which has been observed in several other rocky intertidal systems (Lewis, 
1972). Biota cover on the rocks of both jetties generally increased at 
the lower levels, and differences between sides were not as great. 
Because cover on the exposed side was rarely less than on the wave- 
protected side (Figs. 2 and 3), it is unlikely that wave shock represents 
a major source of mortality as noted in other rocky intertidal systems 
(Dayton, 1971; Menge, 1978). However, wave energy in those systems is 
often considerably greater than the moderate wave energy observed at 
Murrells Inlet. 
Comparisons of biota cover estimates obtained by line-transect versus 
photographic census (Figs. 2 and 3) showed strong similarities except at the 
highest intertidal levels. Blue-green algae were dominant in the upper inter- 
tidal zone, and these species of algae were not assessed in the photographs. 
Since many of the sessile organisms are colonial, species diversity 
indices were not calculated on this component of the jetty communities. 
However, an examination of the number of taxa found on the rocks indicates 
that there were fewer species in the intertidal zone than in the subtidal 
zone on both jetties (Figs. 4 and 5, Appendices A-D). The more rigorous 
physical environment associated with the intertidal habitat obviously 
limits the number of species which can colonize this area as compared with 
the less stressful subtidal environment. 
In both the intertidal and subtidal zones, the number of taxa present 
on the jetty within one year after construction was nearly equivalent to 
or greater than the number found in later years (Figs. 4 and 5). 
Additionally, there were no major or consistent differences in the number 
of taxa found on the wave-exposed versus sheltered sides of the jetties. 
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