Seasonal Development of Bladder Kelp 



George B. Rigg, 

 University of Washington, Seattle. 



INTRODUCTION 



Since exact data as to the state of development of this kelp 

 (Nereocystis luetkeana^) in some one bed at different seasons seemed 

 desirable, the writer began in the fall of 1914 to make observations on 

 the kelp bed at Lincoln beach near the southern boundary of the City of 

 Seattle. Data on the stage of growth of this plant at different seasons, 

 together with discussions in interpretation of the data, have been con- 

 tributed by Frye," ^ Setchell,* '' the writer'' " ^ and others. 



It is not considered necessary in this paper to discuss the structure 

 and development of this plant, since these facts are touched upon in the 

 papers just cited and are more fully considered in a paper by MacMillan.® 



The kelp bed on which these observations have been made has varied 

 a good deal in size at the different dates of observation, reaching its max- 

 imum size in late summer, but at its best development it has exceeded 700 

 feet in length and has shown an average width of more than 40 feet. The 

 height of the tide and the state of the water with regard to waves and 

 tidal currents are also important factors to consider in estimating the size 

 of the bed. Many specimens of this kelp, even in late summer, are too 

 short to reach the surface of the water except at extreme low tide. Many 

 of the plants that would otherwise be readily seen are rendered incon- 

 spicuous by movements of the water due to winds and tides. In extreme 

 cases these causes may render portions of the bed invisible except to an 

 observer in a boat directly over the kelp. 



The following are the dates of observations on this bed, together with 

 the more important facts observed. Each visit except numbers 1, 5 and 



iWhenever the word "kelp" is used in this paper, it refers to this species. 



2Frye, T. C. Nereocystis luetkeana. Bot. Gaz. 42:143-14fi. 1906. 



."•Frve. T. C. The kelp beds of southeast Alaska. Kept. No. 100. U. S. 

 Dept. Agric, pp. 60-72. 1915. 



4Setchen, W. A. Nereocystis and Pelag-ophycus. Bot. Ga-/. 45:12o-13t. 190S. 



"•getchell, "\V. A. The kelps of the coast of the United States and Alaska. 

 Sen. Doc. 190. Sixty-second Cong. Sec. session, pp. 130-177. 1912. 



nRig-ir, G. B. Votes on the ecology and economic importance of Nereocystis 

 luetkeana. PI. World. 15:83-92. 1912. 



"Rigg, G. B. Ecological and economic notes on Puget Sound Kelps. Sen. 

 Doc. 190. Sixty-second Cong. Sec. session, pp. 179-193. 1912. 



sRigg. G. B. The kelp beds of western Alaska. Rept. No. 100. U. S. Dept. 

 Agric. pp. 105-122. 1915. 



nMacMillan, C. Observations on Nereocystis. Bull. Torr. Bot. Club. 26:273. 

 1899. 



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