Shelf Environment (Sublittoral) 



163 



Figure 140. Photographs of 

 bathypelagic coelenterates. 

 Mostly from Hartman and 

 Emery (1956). A, scyphozoan 

 medusa, Santa Catalina Basin 

 — 1329 meters, 4 meters above 

 bottom, Station 2111, April 29, 

 1952; B, abylid siphonophore, 

 San Pedro Basin — 889 meters, 

 2 meters above bottom, Sta- 

 tion 2096, March 29, 1952; C, 

 trachyhne medusa, Santa Cata- 

 lina Basin — 374 meters, 947 

 meters above bottom. Station 

 2099, March 30, 1952; D, 

 bathyphysid siphonophore, 

 slope of Santa Catalina Basin 

 — 634 meters, about 3 meters 

 above bottom, Station 2100, 

 March 30, 1952; E, abylid si- 

 phonophore, slope of San Pedro 

 Basin — 472 meters, 35 meters 

 above bottom. Station 2097, 

 March 29, 1952; F, trachyline 

 medusae, part of a swarm of 

 at least fourteen, San Nicolas 

 Basin — 1703 meters, 76 meters 

 above bottom, Station 2083, 

 November 18, 1951; G, bathy- 

 physid siphonophore, slope of 

 Santa Catahna Basin — 628 me- 

 ters, about 9 meters above bot- 

 tom, Station 2100, March 30, 

 1952. 



B 



kelp, Pelagophycus porra, has a single stipe 

 leading from a holdfast to a double float 

 which is about 15 cm in diameter and above 

 which two branches carry a half-dozen 

 blades each. The blades are as much as 3 

 meters long and 30 cm wide. 



Both Macrocystic and Pelagophycus live 

 in depths as great as 30 meters. During 

 storms the lifting eff"ect of waves on the kelps 

 frequently causes the anchor rock to break 

 away and drag mostly toward shore but 

 sometimes toward the sea. If toward the sea 

 the floats may buoy up the anchor (Fig. 142) 

 and allow the plant to perform a minor geo- 

 logical role — long-distance transportation of 

 rocks (Emery and Tschudy, 1941). When 

 the anchor drags shoreward or the stipe 



breaks and the loose kelp washes ashore, 

 windrows of kelp about a meter thick may 

 pile up on beaches to feed the sand flies and 

 hoppers and discomfit the bathers. Near 

 shore the smaller Pterygophora californica 

 occurs in depths of 3 to 10 meters where the 

 surf is strong. Its stipe is a stiff" wand hav- 

 ing no floats but several long blades branch- 

 ing from its top. Since all three plants 

 require strong attachment to the bottom, 

 they usually are good indicators of rock bot- 

 tom. The same restriction limits its occur- 

 rence largely to waters near the rocky islands 

 and adjacent to the rocky projecting points 

 of the mainland. Because of the value of 

 kelp as a source of algin and formerly of 

 iodine and potassium, it has been harvested 



