426 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 5 



DISPERSAL OF ALGAE 



The distribution of similar species of algae in widely separated 

 geographic areas can be explained by the adaptability of algae to 

 various modes and methods of transportation. Possibly one reason 

 algae are so cosmopolitan is that they are good travelers and ready 

 to seize every opportunity for making a voyage. It is generally as- 

 sumed that the vegetative cells of algae cannot survive desiccation 

 and would perish during transportation through the air. Recent 

 studies on the viability of algae in desiccated soils have shown, how- 

 ever, that many algae that have withstood desiccation for years 

 have no sporelike stages. It is probable that dissemination of vege- 

 tative cells is of far greater importance than that of spores. 



Streams assist greatly in the transportation of algae. The distri- 

 bution of many species of marine algae is due to the ocean currents. 

 The two major agencies of transportation are birds and the wind. 

 The swimming and wading birds, such as sea gulls and ducks, carry 

 the algae in the half-dried mud on their feet. Lodging among the 

 feathers of the birds, the algae are carried about with them also. 

 Migratory aquatic birds carry algae from one lake to another. Re- 

 cent airplane and Zeppelin studies of the spores contained in the 

 air have shown the presence of algal cells in the air above the i)lains 

 as well as over the cold stretches of Labrador and the great ice cap 

 of Greenland. Many algae have been found among the mineral 

 jDarticles and diatoms carried in the great dust storms of the north- 

 west that have left the snow tinged with a grayish coating. Dust 

 clouds originating in Arizona and New Mexico or in the western 

 portion of the Great Plains of the United States have been known 

 to travel east of the Mississippi River before falling to earth. 

 Among the dust particles the algae are thus carried more than a 

 thousand miles from their native habitats. The rain aids in 

 washing the spores of algae to places far from the parent cell. The 

 presence of many species of algae common to the southern and west- 

 ern coasts of Australia on the Atlantic and Mediterranean coasts 

 can be explained by the fact that they were carried there by ships. 

 In the case of Asparagopsis arfnata, the hooks and organs of perma- 

 nent attachment, which are barbed branches, fasten themselves on 

 parts of the ship. Often when tropical higher plants are introduced 

 to aquaria, they bear in their leaves small algae that adapt them- 

 selves to their new environment. At Kew Gardens, in England, 

 many species from South America and Egypt have been introduced 

 in this manner. 



USES OF ALGAE 



Some of the uses of algae have already been mentioned. Probably 

 one of the greatest uses is as food for fishes. Fishes are dependent 



