If wave stress at Murrells Inlet had been greater, differences in the 
diversity of species might have been more apparent, as noted in other 
rocky intertidal systems (Menge and Sutherland, 1976). 
(2). Community Composition 
(a). North Jetty 
Although estimates of total biota cover and the 
number of taxa on the north jetty rocks did not change markedly over 
the four-year study period, community composition of the sessile biota 
did vary considerably between years (Tables 4 and 5; Figs. 6 and 7). 
Major differences were also observed in the intertidal versus subtidal 
community composition and, to a lesser extent, between the wave-exposed 
and protected sides. 
One year after jetty construction, the dominant intertidal species 
at all stations were the barnacle Chthamalus fragilis and the mussel 
Brachidontes exustus. These two species accounted for approximately 
63% of all biota cover in this zone. The oyster Crassostrea virginica 
and the barnacle Balanus eburneus were the only other fauna among the 
ten dominant organisms found intertidally. Blue-green algae (Cyanophyta) 
was the primary intertidal algal form during the first year. The 
dominant species of blue-greens were Anacystts aeruginosa, Microcoleus 
lyngbyaceous, and Calothrix crustacea. These three species were noted 
during all later sampling periods, as well. Other algal species found 
on the rocks included the green algae Cladophora sp. (primarily 
C. laetevtrens) and Ulva sp., and the red algae Hypnea musctformis, 
Lomentarita batleyana and Herpostphonta tenella. Although barnacle and 
mussel cover was generally similar on both sides of the jetty in 1979, 
blue-green and green algae were the predominant algal forms on the exposed 
side, whereas red algae were predominant on the protected side. 
Chthamalus fragilis, Brachtdontes exustus, Ulva sp. and Cyanophyta 
continued to dominate the intertidal biota cover during the next three 
years (Tables 4 and 5). In 1980, rock coverage by the different taxa 
was similar to that observed in 1979 (Figs. 6 and 7), but by 1981, algal 
cover had increased. The line-transect census indicated that blue-green 
algae was more prevalent this year than in any other year. Larger 
macrophyte coverage had also increased to a lesser extent, with green 
algae (Ulva sp., Enteromorpha sp., and Cladophora sp.) generally being 
more common on both sides of the jetty than red algae (Gracilaria 
folitfera, Porphyra sp., Hypnea musctformis and Polystphonta sp.). By 
1982, algal and mussel cover had decreased considerably. Barnacles 
(C. fragilis) represented the dominant biota on the rocks, although blue- 
green algae was also common. 
The decline in algal and mussel cover during the last year of study 
is not readily explained. Some of this decline may be attributed to 
mortality. Additionally, both taxonomic groups were concentrated in 
only the lowest portion of the intertidal zone during all four years, 
and the MLW sampling level represented the upper limit for many of the 
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