MARINK AI.OAL COMMUN'ITIKS OF THE JUAN KKKNANUKZ ISLANDS 



Table II. The Dictvofacctn-C od/inii-R/iodonie/iurac Ass. 



679 



niityota plilyctncnodts 



Pdiiina fe?-nan({c:.iann 



Disfro/niuiii Skottsbcrs^ii 



Codiitm ffrfi(i/!dezi(tni///i . . . . 



Polysiplwnia abscissa 



Ilypoglossum pajuuhaii 



Pterosiphonia dendroidca + 



piisilla 



Microdictyon japwnicuiii 



Colpoiiicnla sinuosa 



Chaetoviorpha liniini 



Cladophora fascicitlaris 



Fernandosiphonia unilatcralis . . 



Liagora brachyclada 



Codiitm cerebrijor/ne 



» unilatera/e 



Halopteris filicina 



Sphacelaria cirrJiosa 



I Cryptoncmia p7-oUfe}-a 



HeterosipJionia subsecundata . . . 

 I Hynienena decumbens 



Plocaiiiiuni paLificiiin 



Rhodytiienia ciineifolia 



» ausiralis 



Schisoseris Dai'isii 



-. + !-, + ,- 



case in Juan Fernandez we do not know. The beach drift should originate from 

 the lower littoral and the upper sublittoral which are more affected by the surf 

 than the deeper water. Nothing forces us to conclude that any of the four 

 species only found drifted, Codium luiilaterale, Laurencia clavata, Plocainiuiii 

 pacificum, and Pterosiphonia disticha, are confined to an intermediate zone, and 

 nothing suggests that a considerable change in the composition of the flora takes 

 place m this unknown region. The lower limit of algal growth is not known; 

 at 30 m and beyond there are still numerous species. 



The picture given by the various dredgings is rather uniform, and with the 

 material at hand only a single community can be distinguished, apart from a 

 couple of local communities observed on a floating buoy. Within this com- 

 munity two associations are distinguishable. 



