FIELD OBSERVATIONS ON THE ALGAE OF THE 

 GULF OF CALIFORNIA 



Elmer Yale Dawson 



Department of Botany, University of California 



It was during the Allan Hancock Expedition of 1940 that the author 

 had an opportunity to obtain information on the condition of the winter 

 algal flora of the Gulf of California. 



Our collections were made between January 18 and February 16, and 

 ranged between Gorda Banks, off the Cape of Baja California, and 

 Rocky Point, Sonora, In July, exactly six months after the Expedition 

 visited Turner's Island, near Tiburon Island in the upper Gulf, a return 

 trip was carried out by automobile and fishing doiy to the same location 

 to observe the seasonal change in the marine flora of that particular 

 station. 



Before entering upon detailed observations on the flora of the Gulf 

 of California, conspicuous general differences from that of the California 

 coast should be stressed. Some of the factors controlling these differences 

 will be discussed. 



Taking the Gulf as a whole, as observed at fully twenty-five different 

 shore stations, the most conspicuous feature was the paucity of seaweeds 

 as compared to the abundance on the rocky shores of California. In many 

 of the more southern localities in the Gulf, the fine rocky places one 

 would expect to find covered with plant life are almost sterile. In the 

 places which do have an abundant rock cover, a great difference exists in 

 the size of the plants. In the Gulf, though many species may occur in a 

 given area, the impression of paucity is due mostly to the absence of the 

 genera of large and conspicuous brown algae, the Kelps and the Fucoids. 

 In short, the marine flora of the Gulf is rich in species but is largely a 

 flora of miniature plants, the great bulk being made up of species of 

 Sargassum. 



As might be expected, the contrast in abundance is less conspicuous in 

 the upper Gulf. The richest algal flora was found among the northern 

 islands from San Esteban to Angel de la Guardia. The greatest number 

 of species collected occurred at Puerto Refugio and at Turner's Island. 

 The abundance of both species and individuals in these regions of the 



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