species. During the 1982 assessment, algae and mussels were abundant 
just below the MLW sampling level. Thus, it is possible that the levels 
selected in that year were slightly higher (2-5 cm) than the levels 
selected in previous years, causing lowered estimates of these taxa. 
In the subtidal zone, different taxa dominated when compared with the 
intertidal zone, and major changes occurred yearly in the most abundant 
biota (Tables 4 and 5, Figs. 6 and 7). One year after construction, the 
subtidal rocks were primarily covered with the mussel B. exustus on the 
exposed side. Rocks on the wave-sheltered side had fewer B. exustus and 
more ascidians (primarily Perophora viridis, Aplidium sp. and Molgula 
manhattensts), but mussels were still the dominant taxon. 
One year later, mussel density had declined significantly and both 
sides had heavy algal cover. The decreased mussel density was most 
likely due to predation by sheepshead (Archosargus probatocephalus) and 
by dense aggregations of the starfish Astertas forbestt, which were seen 
grazing on the mussels during the summer of 1979. Mussel density remained 
low on the subtidal rocks for the remainder of the study. 
Prominent algal species which colonized the rocks during the second 
year included the red algae Gracilaria folitfera and Rhodymenta pseudopal- 
mata, and the green alga Ulva sp. Algae appeared to be more prevalent on 
the exposed side, which may be due to greater light penetration in the 
clearer waters generally observed on that side. Bryozoans were also 
common on the exposed side in 1980, and they were much more abundant 
there than on the wave-protected side. Dominant bryozoans included the 
stalked forms Angutnella palmata and Bugula nerttina, and the encrusting 
form Schtzoporella errata (Tables 4 and 5). On the protected side, 
hydroids and ascidians were more prevalent than bryozoans, which were 
relatively rare on that side. The most common hydroid was Obelta 
dichotoma. This species grew primarily on the red algae. The dominant 
ascidian was Eudtstoma carolinense, which formed large mats of clumped 
zooids having sand-covered tests. Because of its morphological complexity, 
this ascidian species provided excellent habitat for a diversity of smaller, 
more motile invertebrates. 
By 1981, the third year after jetty construction, ascidians had become 
quite common on both sides of the jetty. Eudtstoma carolinense and 
Distaplia bermudensis were the most abundant ascidians on the exposed side, 
and E. carolinense remained as the dominant species on the wave-sheltered 
side (Appendices A and B). Algae was also common on both sides, with red 
algae (G. folttfera and Rk. pseudopalmata) being more prevalent than green 
algae. The hydroid Obelta dichotoma was often observed growing on the red 
algae. Many stalked bryozoans, such as Crista sp., Angutnella palmata, 
and Bugula neritina were commonly observed attached to the rocks. The 
encrusting bryozoan Sehtzoporella errata did not appear to be as common 
in 1981 as in the preceding year, but another encrusting forn, 
Thalamoporeltla gothica, was noted for the first time on the rocks 
(Appendix A). This latter species often grew in large erect colonies 
shaped in the form of lettuce heads. Finally, the octocoral Leptogorgia 
virgulata, was often noted growing on the rocks, especially at the base 
of the jetties. 
29 
