combination of the three. Lomentaria is a 

 rose to red-colored plant that looks like 

 Hypnea but does not have recurved tips. 

 It forms densely branched creeping mats, 

 has hollow axes except at the bases, and 

 its branchlets tend to arch back toward 

 the main axis. Graci 1 aria ti kvahi ae 

 (formerly G^ fol iifera ) is olive green to 

 dark red and has flattened, strap-like 

 blades with pointed tips (Figure 8A) . 

 Although the entire plant may appear 

 irregularly bushy, the branches along each 

 main axis all branch in the plane of the 

 blade. Rhodymenia pseudopalmata is rose 

 to red in color and has strap shaped, 

 dichotomously branching blades with 

 rounded tips. It usually occurs at, or 

 below, the low tide line. Small, wiry 

 turfs of reddish-purple to brown seaweeds 

 in the genus Gel idium also occur in this 

 same habitat. 



On some jetties, green, sponge-like, 

 dichotomously branching algae (Figure 8B) 

 in the genus Codium (commonly called dead 

 man's fingers) are common at this low 

 tidal level. In North Carolina, jetties 

 have traditionally supported populations 

 of Codi urn decorticatum and Codi urn 

 isthmocladium . Within the past decade, 

 the introduced species Codium fragile has 

 invaded down the coast from New England 

 and now makes up a substantial portion of 

 the Codi urn biomass on local jetties 

 (Searles et al . 1984; J. Ramus, Duke 

 University Marine Laboratory, Beaufort, NC; 

 pers. comm.). 



Virtually all of the genera and 

 species mentioned above also occur in the 

 shallow subtidal zone during some times of 

 the year or in some locations. The 

 distinction between intertidal and 

 subtidal seaweeds in the South Atlantic 

 Bight is not always clear and appears to 

 be useful only during some times of the 

 year (Kapraun and Zechman 1982). However, 

 several jetty seaweeds are almost 

 exclusively subtidal . 



The most abundant subtidal seaweed on 

 jetties along much of the coast is the 

 brown alga Sarqassum . It has a wiry main 

 axis, linear leaves with midribs, and 

 stalked, spherical air bladders (Figure 

 8C). In summer, the brown seaweeds Padina 

 and Dictyota are also common. Padina 

 forms a fanshaped, lightly calcified blade 



(Figure 8D) ; Dictyota has membranous, 

 dichotomously branched axes that are brown 

 to golden brown in color (Figure 8E). 



Several other seaweeds are 

 occasionally common in the subtidal zone 

 including: the green alga Bryopsis ; the 

 red algae Chondri a (Figure 8F), 

 Cal 1 i thamnion , Champi a , Dasya , 

 Hypoql ossum . Cal oni tophyl 1 urn , and 

 Grinnel 1 i a ; and the brown algae 

 Ectocarpus , Punctari a , and Petal onia . 

 Given the difficulties associated with 

 seaweed identification, readers interested 

 in seaweeds should consult Taylor (1960) 

 or Kapraun (1980a, 1984) before assigning 

 a name to any seaweed from this coast. 



Distribution 



When researchers study algal 

 communities on rubble structures in the 

 South Atlantic Bight at a single point in 

 time (usually summer), they often describe 

 distinct patterns of zonation based 

 primarily on the upper limits of dominant 

 species (Hoyt 1920; Williams 1949; Earle 

 and Humm 1964). When Kapraun and Zechman 

 (1982) investigated seasonal patterns of 

 vertical zonation on jetties at Masonboro 

 Inlet, NC, they noted what appeared to be 

 relatively distinct intertidal and 

 subtidal communities in the summer, but 

 during the remainder of the year there was 

 no clear separation of communities at the 

 low tide line. During winter and early 

 spring, so called intertidal species like 

 Porphyra carol i nensi s and Enteromorpha 

 prol ifera became abundant in the subtidal 

 zone, but during the summers, they 

 retreated back to the intertidal. Kapraun 

 and Zechman (1982) hypothesized that these 

 changes occurred in response to changing 

 competitive interactions among the plants. 

 However, these changes are also consistent 

 with the hypothesis that fish grazing 

 during the warm portions of the year, when 

 fishes are most numerous, exclude these 

 palatable seaweeds from the subtidal zone. 

 The limited available data suggest that 

 fishes drive several palatable seaweeds to 

 near extinction on subtidal portions of 

 jetties in the summer (Hay 1986). 

 Additionally, recent work in outdoor 

 microcosms has shown that Enteromorpha 

 grows year round in the subtidal zone if 

 fishes are excluded from the system (Hay 

 1986). If fishes are abundant, 



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